18.6 Rebuilding of Bridges 18.6.1 Basic Condition for Bridge ...

The Project for the Planning of the Nadi River Flood Control Structures in the Republic of Fiji

YACHIYO ENGINEERING CO.,LTD./CTI ENGINEERING INTERNATIONAL CO.,LTD. JV

Final Report, Volume II Main Report, Part II: Feasibility Study

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18.6 Rebuilding of Bridges

18.6.1 Basic Condition for Bridge Design

In this section, the fundamental matters for bridge design (design standards, road condition, topographical

and geological condition, and design load) are shown as below.

(1) Design Standards

The following major technical standards as shown in the Table will be applied in the preliminary design of

bridges in this project. There are some bridge design standards based on the standards of New Zealand and

Australia in Fiji. These standards specify the basic regulations such as live loads but details are not

specified. Therefore, the standards of Fiji, New Zealand, Australia and Japan will be referred and decided

properly in order to implement the preliminary design in this project. Furthermore, the details should be

decided through discussion with MOIT when the detailed design is implemented.

Table 18-9 Major Technical Standards and Reference Documents

No. Name Editor / Publishing Office Date of

publication Remarks

1 Cabinet Order concerning Structural Standards for River Management Facilities, etc

Japan River Association January 2000

2 SPECIFICATIONS FOR HIGHWAY BRIDGES Japan Road Association March 2012

3 Cabinet Order on Road Design Standards Japan Road Association February 2004

4 Design Guide - BRIDGE, WHARF, JETTY, CULVERT, AND CROSSING STRUCTURES -

Revision: Version A

Fiji Road Authority June 2015 Bridge Design

Standards

5 GUIDE TO ROAD DESIGN Austroad August 2010 Road Design Standards

6 BRIDGE MANUAL (SP/M/022) Third Edition New Zealand Transport Agency

September 2014 Bridge Design Standards

7 AS/NZS 1170.0:2002 Australian/New Zealand

Standard June 2002

General requirements are

shown in structural design

8 NZS 1170.5: 2004 New Zealand Standard December 2004 Seismic Design Standards

9 NZS 3101:2006 New Zealand Standard March 2006 Design Standards for

Concrete Structures

Source: JICA Study Team

(2) Geometric Structure of Road

In Fiji, there is not any original road design standard, and the “Guide to Road Design” (hereinafter, AU

Road Standard) issued by Austroads is utilized instead. In this design, this standard is utilized for reference.

1) Road Classification

The road standards in Fiji are classified into 2 types according to the “Design Guide – BRIDGE, WHARF,

JETTY, CULVERT AND CROSSING STRUCTURES – Revision: Version A” (hereinafter, FRA

Standards), the routes Rural R1 and Urban Arterial as shown in the following figure are classified as

Importance Level 3, and other roads are classified as Importance Level 2. Therefore, bridges as for FS in

this project are classified as below.

Nadi Town Bridge: Importance Level 3 (Rural R1: a bridge on Queens Road)

Old Queens Road Bridge: Importance Level 2 (Normal Bridge)




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Figure 18-26 Routes as Importance Level 3

Source: Design Guide -BRIDGE, WHARF, JETTY, CULVERTAND CROSSING STRUCTURES-Revision: Version A Date:

June 2015

2) Operating Speed

The design speed is set up considering the site conditions and referring the “AU Road Standard”

requirements as below.

a) Nadi Town Bridge: V=40km/h

The traffic volume of large-sized vehicle is small at the site (most of those come and go Nadi Back Road),

and there is a crossing at the bridge south site (no traffic signal). The necessity to increase the design speed

at south side of crossing is judged to be low because the road shoulder there, as a business area, is used for

parking space. Meanwhile, the existing curve radius R around the crossing is about 50m. Considering the

abovementioned site conditions, the minimum design speed (Operating Speed) is set up as V=40km/h

based on the following reasons.

The minimum design speed (Operating Speed) at Urban Area is V=40km/h (according to AU

Road Standard)

According to AU Road Standard 7.4, the minimum (desirable) curve radius for design speed

(Operating Speed) V=40km/h is R=36m. On the other hand, the minimum (desirable) curve

radius for design speed (Operating Speed) V=50km/h is R=56m. Therefore, the design speed

V=50km/h cannot be applied under the regulation (the satisfied minimum curve radius is found

as R=49, however, it is judged that there is not needed to increase the design speed considering

the site condition).

b) Old Queens Road Bridge: V=60km/h

The large-sized vehicles come and go to the cement factory near the site bridge mostly toward Nadi Back

Road, and they seldom use the bridge. Also, the road front and behind the bridge curves about R=100m.

According to AU Road Standard7.4, the minimum (desirable) curve radius for the design speed (Operating

Speed) V=60km/h is R=94m. On the other hand, the minimum (desirable) curve radius for V=70km/h is

R=154m, so, the design speed V=70km/h cannot be applied under the regulation. Therefore, the design




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speed of V=60km/h is selected.

Table 18-10 Minimum Curve Radius

：Nadi Town Bridge:

：Old Queens Road Bridge

Source: GUIDE TO ROAD DESIGN 7.4

3) Cross Sections

The design cross section is set up as shown below referring FRA Standard, Bridge Manual Third Edition,

Sep. 2014, NZ Transport Agency (hereinafter, NZTA Standard), and the past successful construction results

in Fiji.

Nadi Town Bridge Old Queens Road Bridge

Figure 18-27 Design Cross Section

The reasons for the set-up are shown below.

a) Number of Traffic Lanes

Nadi Town Bridge: 1 Lane for one side bound as same to the current condition

Old Queen Road Bridge: 1 Lane for one side bound as same to the approach road of

front and behind the existing bridge. It was so set up as same to the

approach road due to congestion at the current bridge.




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b) Width of Traffic Lane

The width of traffic lane is set up as 3.5m referring the regulation of Appendix A of NZTA Standard.

Source: Bridge manual Third edition, Sep. 2014, NZ Transport Agency

c) Width of Shoulder

The width of shoulder is set up as 0.3m referring the existing site experience (Denarau Bridge; see figure

below, under construction currently).

Figure 18-28 Cross Section of Denarau Bridge Source: Provided by a local contractor

d) Width of Sidewalk

As shown below;

Nadi Town Bridge: 3.0m (Cycling & Pedestrian Road), 1.5m (Pedestrian

Walkway) (Refer to Improvement Plan for Queens Road)

Old Queens Road Bridge: Referring to NZTA Standard, one side walkway is 1.5m.




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Source: Bridge manual Third edition, Sep. 2014, NZ Transport Agency

e) Width of Barrier Curb

Referring past successful construction results, 0.45m is set up.

4) Gradient and Crossfall

a) Gradient

The steepest gradient is set up referring AU Road Standard 8.5.3, and considering the geographical

conditions around the bridge location and design speed.

Nadi Town Bridge: 8%

No gradient is specified for the design speed (Operating Speed) V=40km/h, therefore, the gradient of

60km/h-Flat is applied and if this application is difficult, it will be reconsidered separately.

Old Queens Road Bridge: 8%

The design speed (Operating Speed) V=60km/h-Flat is applied.

Source: GUIDE TO ROAD DESIGN 7.4 Table 8.3

b) Crossfall

The crossfall is set up as 3% (upgrade from both portal) referring NZTA Standard.

(3) Geometric Structure of Tramline

Since there is no regulation regarding geometric structure of tramline in Fiji, the followings are applied

referring FSC (Fiji Sugar Corporation) and the hearing results from local consultants.




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a) Clearance Limit

It will be set up based on the internal cross section (height H x width B = 5.0m x 5.26m) of Qeleloa Over

Pass which stride over the tramline because no answer was obtained by hearing.

b) Gradient

Horizontal is set up following the direction by FSC.

c) Minimum Curve Radius

The minimum curve radius is set up as R=40m based on the result of hearing to local consultants.

(4) Topographical and Geological Condition

Nadi Town Bridge is located about 10km from the mouth of Nadi River, Old Queens Road Bridge is

located about 17km from the mouth of river, and the former elevation is +6~8m, the latter elevation is

+11~12m on alluvial plain.

Around the Nadi Town Bridge, there are residential zones, business area and plantations. Fruit trees of

banana and papaya, etc., are cultivated. The land around the Old Queens Road Bridge is mainly utilized as

plantation for sugar cane but cement factory and several residential houses are also located near the bridge.

The geological feature around the Nadi Town Bridge is composed by soft silt ~ sandy soil with N value of

less than 10 between 16m ~ 24m from G.L., and diluvial clayey soil stratum with N value of more than 50

below the aforementioned stratum.

The geological feature around the Old queens Road Bridge is composed by silt ~ sandy soil with N value of

less than 30 between G.L. and 24m from G.L., and diluvial clayey soil ~ highly decomposed granite stratum

with N value of more than 50 below the aforementioned stratum.

The location of boring holes is shown after next page. Boring logs are shown in Data Book




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Figure 18-29 Location of Boring Holes (Nadi Town Bridge)

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(5) Crossing Condition

1) Nadi Town Bridge

The crossing condition of Nadi River as a crossing target is summarized in the following table, and

characteristics of river channel are shown below.

River channel is an Embankment structure.

The site belongs to tidal area so that the construction plan (diversion of water) is to be based on the

mean high water springs of +1.188m

Table 18-11 River Condition (Nadi Town Bridge)

Planned

River

Cross

Section

Notices

Design Flood

Discharge 1400 m

3/sec (1/50)

Standard Span

Length*1

L=20.0m

Design High Water

Level +5.76m Number of Piers

*1 5(Lp/L)

River Width Lp=103.28m

(H.W.L)

Existence of

Neighboring Bridge None

Design Bed Slope 1/4200

Maximum

Impediment Ratio of

River Flow*2

5%

Height of River Bed -1.51m Upper Surface of

Footing of Pier River Bed -2m

*3

Height of Dike +6.76m Discharge at

Performing

Construction

Because of tidal area the

average High Water Level is

applied. Form of River

Chanel Embankment

Crossing Angle 90 deg. High Water +1.188m

*1: Cabinet Order concerning Structural Standards for River Management Facilities, etc., Article 63

*2: ditto, Article 62

*3: Lower of current state and design (ditto, Article 62)





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2) Old Queens Road Bridge

The crossing condition of Nadi River as a crossing target is summarized in the following table, and

characteristics of river channel are shown below.

River channel is an Engraved structure.

The normal line at the location of bridge is curve.

Table 18-12 River Condition (Old Queens Road Bridge)

Planned

River

Cross

Section

Notices

Design Flood

Discharge 1400 m

3/sec (1/50)

Standard Span

Length*1

L=20.0m

Design High Water

Level +9.73m Number of Piers

*1 4(Lp/L)

River Width Lp=89.40m

(H.W.L)

Existence of

Neighboring Bridge YES

Design Bed Slope 1/2600

Maximum

Impediment Ratio of

River Flow*2

5%

Height of River Bed +0.78m Upper Surface of

Footing of Pier River Bed -2m

*3

Height of Dike +10.73m Discharge at

Performing

Construction

The discharge is estimated

based on the maximum

water level in non-flood season in the past.

Form of River

Chanel

Engraved

(Height of Landside is higher than H.W.L)

Crossing Angle 80 deg. High Water ---

*1: Cabinet Order concerning Structural Standards for River Management Facilities, etc., Article 63

*2: ditto, Article 62

*3: Lower of current state and design (ditto, Article 62)





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(6) Design Load

The basic requirements for bridge design are specified in “Design Guide – BRIDGE, WHARF, JETTY,

CULVERT AND CROSSING STRUCTURES – June 2015, Fiji Road Authority (hereinafter, FRA

Standards) which was issued as the bridge design standards in Fiji. On the other hand, details are required

to refer “Bridge Manual Third Edition, 2015, The New Zealand Transport Agency” (hereinafter, NZTA

Standards) and so on, to the design standard of New Zealand. Following the above-mentioned standards,

the loading conditions are summarized as shown below.

1) Live Road

a) Road Bridge

The vehicle loading is set up following the NZTA Standards Section 3.2 as shown below.

Figure 18-31 Vehicle Loading

Source: Bridge Manual Third Edition (2014, the New Zealand Transport Agency)

The crowd loading applies 5.0kPa following Section 3.4 of NZTA Standards.

b) Tramline Bridge

The live load for design of Tramline is set up following B4.2 of FRA Standard as shown below.

Figure 18-32 Design Live Load (Tramline Bridge)




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2) Wind Road

The wind road refers “AS/NZS 1170.0:2002, Australian/New Zealand Standard”. Basic design wind load is

set up as V=70m/s following the FRA Standard B4.4. The wind direction multiplier is set up as 1.

3) Temperature Variation

Temperature variation is set up as bellow following NZTA Standard 3.4.6.

Steel structure: ±25℃

Concrete structure: ±20℃

4) Seismic Design

The design horizontal seismic load V is set up following FRA Standard, NZTA Standard and NZS

1170.5:2004, New Zealand Standard, December 2004, as shown below.

V=Cμ･Z･R･Sp･Wd≧0.05Wd

where,

Wd: self-weight

Sp: coefficient of structural capacity (compensation coefficient for each ground type)

R: coefficient of dangerousness (significant coefficient)

Z: regional coefficient

Cμ: response spectrum of basic acceleration

5) Combination of load effects

a) Load Combinations and Load Factors for the Serviceability Limit State

b) Since the various loads act the structures at same time in service and in construction, the

disadvantage combination of loads is to be considered. Table 18-13 shows case of

combination and coefficient multiplied to load.




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Table 18-13 Load Combination for Serviceability Limit State

c) Load Combinations and Load Factors for the Ultimate Limit State

Table 18-14 Load Combination for Ultimate Limit State






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18.6.2 Preliminary Design of Nadi Town Bridge

(1) Summary The bridge concerned is located at the crossing point of primary arterial road of Queens Road over Nadi River (see Figure18-33(1), and it is a 3 span steel cantilever girder bridge + simple span steel girder bridge, of which bridge length is 72.0m, constructed in year 1865 (see Photo18-1, Figure18-33(2)). This bridge was planned to be rebuilt since the clearance below girder had become disable to keep the freeboard due to the shortening of bridge length after maintenance work by river widening. The rebuilt bridge was planned to be located at the same place to the existing bridge due to the limitation of land, and the bridge length was planned to be 108m based on the designed river cross section (see Figure18-34).

The HWL around the rebuilt bridge location is quite high; it is no other way to raise the design vertical alignment higher than existing bridge in order to keep the design freeboard below girder. Also, it was needed to employ the low height girder bridge because the elevation of road surface could not be raised due to the neighboring traffic junction and shopping street with consideration of river block and cost issue. Therefore, 3 span PC continuous post-tension T Girder Bridge was planned considering the past results of successful construction and the cost performance.

Figure 18-33(2) Existing Bridge Side View (Nadi Town Bridge) Source: JICA Study Team

Figure 18-34 Rebuilt Bridge Side View (Nadi Town Bridge) Source: JICA Study Team

Figure 18-33 (1)Bridge Location

Photo18-1 Current Bridge


YACHIYO ENGINEERING CO.,LTD./CTI ENGINEERING CO.,LTD. JV


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The pier was planned as oval wall type because the pier was constructed in the river. The foundation was

planned by pile (cast in place pile with casing remained).

(2) Consideration of Road Alignments

1) Design Policy

In this planning project, cross sectional plan, horizontal & vertical alignment are examined, and also the

road alignment for bridge section and approach road section of front & behind the existing bridge is

planned in order not to redo the detailed road & bridge design in the future.

The basic principle in this planning is shown as below.

[Basic Principle]

The number of carriage way should be same to the existing bridge.

The horizontal alignment should not be changed due to the limitation of land.

The vertical alignment should be set up being based on the girder height of the specified type of

below-mentioned superstructure, and the clearance below girder. Also, the approach road of front and

behind the existing bridge is connected to the present earth work section but it is needed not to raise

the elevation of road surface around the neighboring traffic junction and to keep the access to the

neighboring shopping stores and residential houses. For make this realized, with consideration of

mobility, transition toward the existing elevation is considered making the improvement area as

shorter as possible under the applicable standards.

2) Consideration of Road Alignments

The plan and vertical section drawings, which are set up following the above mentioned principal, are

shown in the next page.

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Transition at Sta.314

Transition at

Sta.106

Vertical gradient of 8% was

selected to minimize improvement

area and to keep clearance below

girder at the Abutment.

Vertical gradient of 8% was

selected to minimize improvement

area and to keep clearance below

girder at the Abutment.

Overlay about 56cm at the Crossing

Transition at STA.31 Figure 18-35 Design Plan and Side View (Nadi Town Bridge)


Clearance below girder

1.04m≧1.0m(OK) at the

location of Abutment

Clearance below girder

1.04m≧1.0m(OK) at the

location of Abutment




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(3) Bridge Planning

1) Location of Abutment

a) Basic Policy Regarding the location of Abutment, it is set up referring the “Cabinet Order concerning Structural Standards for River Management Facilities, etc.” Clause 61.

Location of front face of Abutment: Rear side behind the normal line at high water

Direction of Abutment: Parallel to the Embankment

Bottom of basement: To be installed lower than bottom embankment Normal Line at High Water Embankment

Bottom Embankment Bottom Embankment

Figure-1 Location of Abutment (River Width ≧50m) Figure-2 Division of Embankment and Ground

The followings are assumed for simplification of design and construction.

Bridge length is set up on the center line of road with 1m round.

Bridge height is set up with 0.5m round.

Footing earth cover is kept more than 50cm considering installation of block revetment.

b) Location of Abutment The location of Abutment is set up as below following the above-mentioned principle.

A1 Abutment: STA. 146.000


Bridge Length: 108.0m




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2) Span Arrangement

a) Basic Policy

Span division is arranged considering structural stability and to minimize the number of piers following the

below principle.

1. Refer the “Cabinet Order concerning Structural Standards for River Management Facilities, etc.”

Arrangement of 6 or less span numbers (5 piers) referring Clause 63 “Span Length”

Blocking ratio by river deposits of 5% or less referring Clause 62

Distance of 10m or more from river bank, slope toe and slope shoulder of low water river bank

referring Clause 62

2. Consideration of actual successful bridge construction results in Fiji

Actual successful construction results in Fiji (around 35m or less precast PC girders)

3. Crossing adjacent to

Minimize the overlay of road surface at crossing adjacent to the bridge.

b) Span Length

Following the above-mentioned principle, the possible-applied span division is such arranged as the 3 cases

below.

2 spans: 2@54m

3 spans: 3@36m

4 spans： 4@27m

The span arrangement is determined as 3 spans [email protected] due to the following reasons.

In case of 4 spans a pier has to be installed within 10m from the end of revetment of river which is

prohibited by law so that the application of this span arrangement is difficult.

In case of 2 spans, the girder height will be very high (2.5~3.6m) and transition with front & rear

embankment will be impossible, in addition to this even if PC Box girder bridge is adopted,

overhanging beam method or launched construction have to be applied. These methods require

scaffolding within the river so that river flow blocking occur. These methods also require large-scale

temporary works for superstructures and are uneconomical comparing with the selected

arrangement. In case of 2 span steel girder bridge, launching is also to be applied because of the

same reason to the above-mentioned type. Therefore this span arrangement is difficult to be applied.

3) Superstructure Type

For study of this bridge structural type, the type of PC Bridge is also examined together with existing steel

bridge types. Moreover, the following 3 cases are picked up considering the actual successful construction

results in Fiji, and also the applied span length as shown in the below Table 18-15.

Table 18-15 Draft Comparison of Bridge Type（Nadi Town Bridge）

Bridge Type Reason of Application

Case-1：PC-3span Continuous Post-Tension T-Girder Common type which is applied in Fiji

Case-2：PC-3span Continuous Component Girder Applicable PC girder type as same as Case-1

Case-3：Steel 3span Continuous Non-Composite Girder Same type to the existing bridge

The result of comparison for the above-mentioned 3 cases from the viewpoints of economy, construction

and maintenance, is shown in Table 18-16 below. Following the result of comparison, Case-1 PC-3span

Continuous Post-Tension T-Girder is selected.

mailto:[email protected]




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Table 18-16 Comparison & Selection of Bridge Type（Nadi Town Bridge）

Case-1

PC-3span Continuous Post-Tension

T-Girder Bridge

Case-2

PC-3span Continuous Component Girder

Bridge

Case-3

Steel 3span Continuous Non-Composite

Girder Bridge

Typical

Cross Section

Outline of Structures

Because Span max＞34m, T girder,

which Flange is wider than I shape

girder, is applied for main beam.

There are past successful results of

construction in Fiji.

T girder is applied for main beam as

same as Case-1 but PC slab is

installed between the girders to reduce Nos. of main beam.

This type of superstructure is

commonly applied in Japan.

Span between girders is arranged to be

less than 3m with I girder, cross frame

and cross beam.

Similar type to existing bridge, many

past successful results of construction

in Fiji.

Method Girder Installation by Erection Beam Girder Installation by Erection Beam Launched Installation of Girders

Construct-a

bility

Girder and beam are fabricated at work yard behind abutment; girders

are installed by erection beam

method. There are many successful

experiences in Fiji.

○

Method of girder installation is same to Case-1.

○

Rail facility is arranged at work yard behind abutment; girders are

launched and installed. Larger

work yard is required, less

constructability

△

Maintena

nce

Durability against decline is higher

than Case-3 because of concrete type and maintenance can be easier.

◎

Maintenance is same to Case-1

◎

Maintenance cost will be more than

other cases due to a steel girder type with many structural

members.

△

Economic Ratio

1.0 ◎ 1.2 △ 1.3 △

Evaluation

This case is selected because of

economic method, many past successful experiences for sure

construction in Fiji. ◎

This case is not selected because of

uneconomic method due to particular form work &

transportation, and also less

experience in Fiji

△


less constructability and more maintenance cost. △

Remarks: ◎:very good, ○:good, △:fair


4) Foundation Type

a) Abutment Type

Various types of abutments could be adopted depending on structure heights, supporting soil

conditions, and economic efficiency. Generally, it is said to be appreciate to decide abutment types

depending on the height of structures. Designed heights for abutments of reconstructed bridges would

be between 3.5 and 9.0 meters, and since supporting soil conditions are not good, inverted T-type

(Cantilever Type) abutments would be adopted.




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Table 18-17 Abutment Types and Standard Heights

Gravity Type

Semi-gravity Type

Cantilever Type

Counterfort Type

Rigid Frame Type

RemarksAbutment Type10 20 30

Height(m)

Source: JICA Study Team based on Design Procedure of each Regional Development Bureau, Ministry of Land,

Infrastructure, Transport and Tourism

b) Pier Types

The pier type is desirable to be long oval type in cross section to avoid disturbance of river flow as

specified in Clause 62 of “Cabinet Order concerning Structural Standards for River Management Facilities,

etc.” so that the wall type pier is adopted6. In consideration of possible future deterioration such as

degradation of stability of the piers by local erosion and the influence on river management facilities,

piers are designed to have footings with sufficient embedment from the riverbed.


Figure 18-36 The wall type pier

6 There are some examples of Rahmen type and Pile Bent type pier mainly due to economical reason.

5) Selection of Foundation Type

The foundation type of this bridge is to be pile foundation because the bearing layer exists deeper than

16m~24m from the boring investigation results. The following 3 type of pile foundation is compared based

on the actual construction in Fiji as shown in Table 18-18.

The foundation type of this bridge is to be Case-1: Cast in place Concrete Pile according to the following

reasons.

・Bearing layer is deep

・Load scale is large

・Hearing results from the local contractors’ opinion based on the above conditions

A A

Side view Cross Section A-A

Semicircular nose and tail

Triangular nose and tail




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Table 18-18 Selection of Foundation Type（Nadi Town Bridge）

Case-1:Cast in place Concrete Pile Case-2：H Bearing Pile Case-3：Anchor Pile

Outline

Reinforcing bars and

concrete are installed within

the steel casing.

Main member is H shape

steel column, and pile head

is fixed by spiral bar and

steel casing.

Anchor bars and concrete

are installed within the steel

casing (anchorage to

bearing stratum).

Typical

Sketch

*1

*2

*3

Appropriate

depth (m) Less than approx.60m Less than approx.15m Less than approx.15m

Loading

Scale Middle~Large Small Small

Applicability ○ △ △

Remarks: ○:good, △:fair

Source：*1: Denarau Bridge Project, *2: Vatuboro Bridge Project, *3: Lomawai Bridege Project

Steel Casing H shape

Steel Column

Anchor Bar

Spiral Bars

Reinforcing Bars

Steel Casing

Steel Casing

Concrete

Spiral Bars




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18.6.3 Preliminary Design of Old Queens Road Bridge

(1) Summary The bridge concerned is located at the crossing point of primary rural road of Old Nadi Back Road over Nadi River (see Figure 18-37(1)), and it is a 9 span simple steel bridge, of which bridge length is 99.3m, constructed in year 1936. Width is about 3m and sidewalk was constructed on the overhanging beam additionally. Moreover, tramline also passes on this bridge girder, which span is divided as same to the road bridge, and the substructure is united in one body (see Photo18-2, Figure 18-37(2)). This bridge was decided to be reconstructed because of the following reasons.

Span length is short (maximum span length is 12.3m, pier quantity is 8 nos., meanwhile, the Cabinet Order concerning structural Standards for River Management Facilities, etc. specifies; standard span length is 20m, maximum pier quantity is 4 nos.) and because of inconsistency between the direction of river normal line and the direction of piers after the improvement, river flow blockage was anticipated.

Because piers were located within the planned slope, this bridge dose not conform to “Cabinet Order concerning Structural Standards for River Management Facilities, etc.”

Because the foundation was exposed due to the scouring of river bed, structural stability became a big issue.

The reconstructed bridge was planned as below considering the site conditions and planned cross section of the river (see Figure 18-38).

1) Road Bridge Road width was planned as one lane for one side bound as same to the approach road of front and behind the bridge, and the tramline was planned to move to the lower river side due to the land limitation.

The clearance below girder was secured by raise of vertical alignment higher than current elevation because of high HWL. Meanwhile, formation level of road surface was unable to rise because of adjacent cement factory or many residential houses, also river blockage and cost were to be considered; it was required to employ low height girders. Hence, PC 3span Continuous Post Tension I Girder Bridge (bridge length 96m) was planned as the bridge type considering the past successful construction results in Fiji and construction cost.

2) Tramline Bridge “Through bridge type” was selected to secure the clearance below girder because the vertical alignment was unable to change considering the climbing capacity and safe operation of tram.

Steel 3span Continuous Through-Bridge with same span division to Road Bridge was selected as bridge type considering past successful construction results in Fiji and construction cost.

Figure 18-37 (1) Bridge Location

Photo 18-2 Site Photo




18-55

Road Bridge

Figure 18-37(2) Side View of Existing Bridge (Old Queens Road Bridge) Source: JICA Study Team

Road Bridge

Tramline Bridge

Figure 18-38 Side View of Rebuilt Bridge (Old Queens Road Bridge) Source: JICA Study Team




18-56

3) Substructure

Planned river normal line (slant angle 80 degrees) was employed for substructures. Road Bridge and

Tramline Bridge were united in one body and spread type was employed for pier foundation because of

shallow bearing stratum. Pile type was employed for abutment foundation because of deep bearing stratum.

(2) Consideration of Alignments

1) Design Policy

In this planning project, cross sectional plan, horizontal & vertical alignment are examined, and also the

road & tramline alignments for bridge section and approach road section of front & behind the existing

bridge are planned in order not redo the detailed road & bridge design in the future. The basic principle in

this planning is shown as below.

[Basic Principle]

Road width was planned as one lane for one side bound as same to the approach road of front and

behind the bridge. Horizontal alignment should be controlled by the land of cement factory on right

bank.

Vertical alignment of road should be controlled by girder height of superstructure type as mentioned

below and the clearance under girder. The transition of alignment is at the approach road section of

front and behind the bridge. The access should be secured limiting raise of road surface around the

entrance of cement factory.

Horizontal alignment of tramline should be parallel to the road and the transition should be toward the

existing road. The vertical transition should be toward the same level to the current condition

considering the climbing capacity and safe operation of tram.

2) Consideration of Alignments

Plan and side view drawings are shown in next page following the above mentioned principle.

Th

e P

roject

for

the

Pla

nn

ing

of

the

Na

di

River

Flo

od

Con

trol

Stru

ctures

in

the

Rep

ublic

of

Fiji

YA

CH

IYO

E

NG

INE

ER

ING

C

O.,L

TD

./CT

I E

NG

INE

ER

ING

C

O.,L

TD

. JV

Fin

al

Rep

ort,

Vo

lum

e II

Ma

in

Rep

ort,

Pa

rt II:

Fea

sibility

Stu

dy

18

-57

Figure 18-39 Plan and Side View (Old Queens Road Bridge)


Transition at

STA.106 Transition at

STA.280

Transition at

STA.280 (entrance of

cement factory)

Control point for

horizontal align

–ment (land of

cement factory)

Rail of Tramline

is moved for 2.8m

to lower river

stream side to

secure control

conditions.

Clearance below

girder at A1 =

1.1m ＞ 1.0m (OK)




18-58

(3) Bridge Planning

1) Location of Abutment

a) Basic Policy

Regarding the location of Abutment, it is set up referring the “Cabinet Order concerning Structural

Standards for River Management Facilities, etc.” Clause 61.

Location of front face of Abutment: Rear side behind the normal line at high water

Direction of Abutment: Parallel to the Embankment

Bottom of basement: To be installed lower than the line connecting river bed

and top of embankment.

Width equal to top of Embankment

↓Normal Line at High Water

The followings are assumed for simplification of design and construction.

Bridge length is set up on the center line of road with 1m round.

Bridge height is set up with 0.5m round in case of spread footing and 0.1m round in case of pile

foundation.

Footing earth cover is kept more than 50cm considering installation of block revetment.

b) Location of Abutment

The location of Abutment is set up as below following the above-mentioned principle (see Figure 8-98).



Bridge Length: 96.0m

Figure -2 Location of Abutment (River Width≧50m) Figure-2 Location of Abutment for Excavated River Bed




18-59

2) Span Arrangement

a) Basic Policy

Span division is arranged considering structural stability and to minimize the number of piers following the

below principle.

1. Refer the “Cabinet Order concerning Structural Standards for River Management Facilities, etc.”

Arrangement of 5 or less span numbers (4 piers) referring Clause 63 “Span Length”

Blocking ratio by river deposits of 5% or less referring Clause 62

Distance of 10m or more from river bank, slope toe and slope shoulder of low water river bank

referring Clause 62. If piers were to be located adjacent to river bank or slope toe of embankment,

or top of slope of low waterway, the revetment should be strengthened if necessary, and river bed

protection or high water protection should be arranged.

2. Consideration of actual successful bridge construction results in Fiji

Actual successful construction results in Fiji (around 35m or less precast PC girders)

3. Crossing adjacent to

Minimize the overlay of road surface at the entrance adjacent to cement factory or residential houses

near the bridge.

b) Span Length

Following the above-mentioned principle, the possible-applied span division is such arranged as the below

3 cases.

2 spans: 2@48m

3 spans: 3@32m

4 spans 4@24m

The span arrangement is determined as 3 spans [email protected] due to the following reasons.

In case of 4 spans a pier has to be installed within 10m from the end of revetment of river which is

prohibited by law so that the application of this span arrangement is difficult.

In case of 2 spans, the girder height will be very high (2.5~3.6m) and transition with front & rear

embankment will be impossible, in addition to this even if PC Box girder bridge is adopted,

overhanging beam method or launched construction have to be applied. These methods require

scaffolding within the river so that river flow blocking occur. These methods also require large-scale

temporary works for superstructures and are uneconomical comparing with the selected

arrangement. In case of 2 span steel girder bridge, launching is also to be applied because of the

same reason to the above-mentioned type. Therefore this span arrangement is difficult to be apply.

3) Superstructure Type

a) Road Bridge

For study of Road Bridge structural type, the type of PC Bridge is also examined together with existing

steel bridge types. Moreover, the following 3 cases are picked up considering the actual successful

construction results in Fiji, and also the applied span length as shown in the below in Table 18-19.

Table 18-19 Comparison of Bridge Type (Old Queens Road Bridge -Road Bridge-)



Case-2：PC-3span Continuous Component Girder Applicable PC girder type as same as Case-1

Case-3：Steel 3span Continuous Non-Composite Girder Same type to the existing bridge


and maintenance, is shown in Table 18-20 below. Following the result of comparison, Case-1 PC-3span

Continuous Post-Tension T-Girder is selected.

mailto:[email protected]




18-60

Table 18-20 Comparison & Selection of Bridge Type（Old Queens Road Bridge -Road Bridge-）

Case-1


T-Girder Bridge

Case-2

PC-3span Continuous Component Girder

Bridge

Case-3

Steel 3span Continuous Non-Composite

Girder Bridge

Typical

Cross Section

Outline of Structures

I-section Post Tension girder is applied

for main beam.

There are past successful results of construction in Fiji.

T girder is applied for main beam as

same as Case-1 but PC slab is

installed between the girders to reduce Nos. of main beam.

This type of superstructure is

commonly applied in Japan.

Span between girders is arranged to be

less than 3m with I girder, cross frame

and cross beam.

Similar type to existing bridge, many

past successful results of construction

in Fiji.

Method Girder Installation by Erection Beam Girder Installation by Erection Beam Launched Installation of Girders

Construct-a

bility

Girder and beam are fabricated at

work yard behind abutment; girders

are installed by erection beam method. There are many successful

experiences in Fiji.

○

Method of girder installation is

same to Case-1.

○

Rail facility is arranged at work

yard behind abutment; girders are

launched and installed. Larger work yard is required, less

constructability

△

Maintena

nce

Durability against decline is higher than Case-3 because of concrete

type and maintenance can be easier. ◎


◎

Maintenance cost will be more than other cases due to a steel

girder type with many structural

members.

△

Economic Ratio

1.0 ◎ 1.3 △ 1.4 ○

Evaluation


economic method, many past successful experiences for sure

construction in Fiji. ◎


uneconomic method due to particular form work &

transportation, and also less

experience in Fiji

△


less constructability and more maintenance cost. △

Source: JICA Study Team Remarks: ◎:very good, ○:good, △:fair

b) Tramline Bridge

The type of Tramline Bridge is selected being limited due to conditions of vertical alignment and High

Water Level. Following 3 cases are picked up considering the actual successful construction results in Fiji,

and also the applied span length as shown in the below Table 18-21.

Table 18-21 Comparison of Bridge Type (Old Queens Road Bridge -Tramline Bridge-)



Case-2：PC-3span Continuous Through-Bridge PC girder type applicable to girder height limitation

Case-3：Steel 3span Continuous Through-Bridge Steel girder type applicable to girder height limitation


and maintenance, is shown in Table 18-22 below. Following the result of comparison, Case-3 “Steel 3span

Continuous Through-Bridge” is selected.




18-61

Table 18-22 Comparison & Selection of Bridge Type（Old Queens Road Bridge -Tramline Bridge-）

Case-1


I-Girder Bridge

Case-2

PC-3span Continuous Through-Bridge

Case-3

Steel 3span Continuous Through-Bridge

Typical

Cross Section

Outline of

Structures

I-section Post Tension girder is applied

for main beam.

There are past successful results of construction in Fiji.

Main girder is PC structure as same to

Case-1. The girder height is reduced

by application of Through-Bridge type.

Bridge slab is Through-Bridge type as

same to Case-2 but steel girder is

employed for main girder.

Method Installation by Crane

(on the slab of Road Bridge)

Launched Installation of Girders

(too heavy for Crane installation)

Installation by Crane

(on the slab of Road Bridge)

Construct-a

bility

Girder and beam are fabricated at work yard behind abutment; girders

are installed by crane method. There

are many successful experiences in Fiji.

○

Girders are fabricated at work yard behind abutment and installed by

launched method. There is no

experience in Fiji, heavy and less constructability.

△

Main girders are fabricated behind abutment and installed by crane

method. The lightest weight of

girder makes the constructability well.

○

Maintena

nce

Durability against decline is higher

than Case-3 because of concrete type and maintenance can be easier.

◎


◎

Many structural members are

needed but maintenance is easier than others because of

Through-Bridge type.

○

Economic

Ratio --*1 - 1.2 △ 1.0 ○

Evaluation --*1 ×


non-experience in Fiji, also the

erection method is limited only by the launched method of no

experience.

△


cost performance advantage and

past successful results in Fiji. ◎

--*1: Evaluation is excluded because of Clearance below primary girder cannot be satisfied.

Source: JICA Study Team Remarks: ◎:very good, ○:good, △:fair

4)Foundation Type

a) Abutment Type

Various types of abutments could be adopted depending on structure heights, supporting soil

conditions, and economic efficiency. Generally, it is said to be appreciate to decide abutment types

depending on the height of structures. Designed heights for abutments of reconstructed bridges would

be between 3.5 and 9.0 meters, and since supporting soil conditions are not good, inverted T-type

(Cantilever Type) abutments would be adopted.




18-62

Table 18-23 Abutment Types and Standard Heights

Gravity Type

Semi-gravity Type

Cantilever Type

Counterfort Type

Rigid Frame Type

RemarksAbutment Type10 20 30

Height(m)

Source: JICA Study Team based on Design Procedure of each Regional Development Bureau, Ministry of Land,

Infrastructure, Transport and Tourism

b) Pier Types

The pier type is desirable to be long oval type in cross section to avoid disturbance of river flow as

specified in Clause 62 of “Cabinet Order concerning Structural Standards for River Management Facilities,

etc.” so that the wall type pier is adopted7. In consideration of possible future deterioration such as

degradation of stability of the piers by local erosion and the influence on river management facilities,

piers are designed to have footings with sufficient embedment from the riverbed.


Figure 18-40 The wall type pier

7 There are some examples of Rahmen type and Pile Bent type pier mainly due to economical reason.

A A

Side view Cross Section A-A

Semicircular nose and tail

Triangular nose and tail




18-63

5) Selection of Foundation Type

The foundation type of this bridge is to be pile foundation because the bearing layer exists deeper than 24m

from the boring investigation results. The following 3 type of pile foundation is compared based on the

actual construction in Fiji as shown in Table 18-24.

The foundation type of this bridge is to be Case-1: Cast in place Concrete Pile according to the following

reasons.

・Bearing layer is deep

・Load scale is large

・Hearing results from the local contractors’ opinion based on the above conditions

Table 18-24 Selection of Foundation Type（Old Queens Road Bridge）

Case-1:Cast in place Concrete Pile Case-2：H Bearing Pile Case-3：Anchor Pile

Outline

Reinforcing bars and

concrete are installed within

the steel casing.

Main member is H shape

steel column, and pile head

is fixed by spiral bar and

steel casing.

Anchor bars and concrete

are installed within the steel

casing (anchorage to

bearing stratum).

Typical

Sketch

*1

*2

*3

Appropriate

depth (m) Less than approx.60m Less than approx.15m Less than approx.15m

Loading

Scale Middle~Big Small Small

Applicability ○ △ △

Remarks: ○:good, △:fair

Source：*1: Denarau Bridge Project, *2: Vatuboro Bridge Project, *3: Lomawai Bridege Project

However the foundation of pier is to be placed directly on the bearing layer which exists shallow depth

from riverbed.

Steel Casing H shape

Steel Column

Anchor Bar

Spiral Bars

Reinforcing Bars

Steel Casing

Steel Casing

Concrete

Spiral Bars




18-64

18.7 Approximate Construction Quantity

18.7.1 Approximate Construction Quantity

Approximate Construction Quantity is as mentioned in Table 18-25 and 18-26.

Table 18-25 Approximate Construction Quantity (River Works)

Quantity Quantity Quantity Quantity Quantity Quantity

Excavation m3 3,928,181.0 1,257,034.5 6,446.0 290,737.0 23,431.0 5,505,829.5

Backfill m3 868,327.0 21,606.0 34,398.0 924,331.0

Embankment m3 328,936.0 1,159,681.3 57,364.0 251,216.0 27,725.0 1,824,922.3

Trimming of slope (Cuting) m2 349,832.7 168,133.6 61,321.0 7,568.0 586,855.3

Stripping topsoil m2 1,375,000.0 305,000.0 37,387.0 222,240.0 12,092.0 1,951,719.0

Gabion m2 - 1,878.8 - - - 1,878.8

Prevent of Crown of levee m2 110,000.0 5,141.9 7,084.0 19,000.0 - 141,225.9

Planting m2 95,760.0 410,498.1 30,807.0 94,236.0 - 631,301.1

Structures Overflow Dike LS - 2 - - - 2

Drainage Sluice Gate LS - 2 - - - 2

Flap Gate LS 8 2 1 1 - 12

Flood Wall Gate LS - - - 1 - 1

Disposal Dozing and Loading m3 2,659,223.0 97,353.2 - - - 2,756,576.2

Transportation m3 2,659,223.0 97,353.2 - - - 2,756,576.2

Embankment m3 2,659,223.0 97,353.2 - - - 2,756,576.2

Coffer Dam m3 752,000.0 - - - - 752,000.0

Temporary Road m2 84,000.0 - - - - 84,000.0

Compensation Works

Pavement pavement (t=0.4m) m² - 6,724.0 - - - 6,724.0

Ⅰ .　Approximate Construction Quantity

Quantity of Main Works

Quantity of Temporary Works

Short cut of tributariesItem Main Works Description Unit

Package-1 Package-2 Package-3 Package-4

Surrounding DikeRiver Widening Retarding Basin A, B Ring Dike

Earth Work

Bank Protection

Embankment

Temporary

Work

Total




18-65

Table 18-26 Approximate Construction Quantity (Bridge Works)

No. unit

0000 Earth work

0001 Excavation(soil) m3 15,457 14,646

0005 Backfill(clean sand) m3 4,718 4,649

0007 Banking m3 1,414 990

0009 Cutting (soil) m3 3,890 0

0010 Trimming of slope (Cutting) m2 148 211

0011 Trimming of slope (Banking) m2 318 193

0100 Foudation Work

0103 casing cast-in-place pile(φ1.0m) m 682 630

0200 Substructure Work

0201 cobble foundation of structure excavation(t=0.2m) m2 277 485

0202 levelling concrete(t=0.1m) m2 277 485

0210 abutment/pier base concrete m3 1,458 2,108

0220 form (for wall, pier) m2 1,380 1,738

0221 form (for levelling concrete) m2 15 21

0230 Rebar for the reinforcement of concrete ton 209 301

0300 Superstructure Work

0301 produce,transport & erection of main beam (PC I-Beam, L=32m)unit 0 21

0302 produce,transport & erection of main beam (PC T-Beam, L=36m)unit 21 0

0350 Steel Girder Bridge (Through Bridge)L=96m(3@32m) m2 0 691

0400 Floor Slab Work

0402 floor slab concrete c=400kg m3 555 298

0403 form (for slab) m2 704 969

0404 Rebar for the reinforcement of concrete ton 56 30

0405 supporting (for slab) m2 1,771 1,286

0500 Bridge Attachment Work

0501 bearing unit 42 50

0502 expansion joint m 26 34

0600 Bridge Surface Work

0604 Guard fence m 216 192

0605 Waterproofing m2 1,404 960

0606 Asphalt pavement for bridge 50thick m2 1,404 960

0700 Removal of Existing Bridge Work

0701 concrete bridge breaking work m3 563 294

0702 concrete waste disposition m3 611 335

0703 steel bridge breaking work ton 92 146

0704 Removal of Existing Pile m 400 460

0800 Pavement Work

0801 road upper subbase m2 1,756 3,092

0803 Asphalt pavement for approach m2 1,756 1,200

0850 Tramline Orbit ton 0 17

0900 Temporary Work

0901 Temporary bridge with H beam m2 576 576

0902 Pile with H Beam (H=350) m 35 35

0904 Big sandbag unit 750 420

0905 temporary construction road m2 2,000 2,840

0906 Hume Pipe (φ1.0m) m 0 150

0907 Coffeing Works m3 8,515 3,720

1000 Concrete Work

1011 Concrete 18Mpa m3 632 447

1020 Form m2 1,275 951

1040 Crushed Stone (t=0.2m) m2 538 406

1100 Dike Works

1101 Pavement of Crown of levee m2 264 376

1102 Plant spraying m2 148 211

1200 Revetment Work

1203 Concrete blocks for bank protection m2 918 1,776

1300 Removal of Surplus Soil Works

1301 Dozing and Loading m3 4,700 5,287

1302 Filling materials transport (≦5.5km) m3 4,700 5,287

1303 Banking m3 4,700 5,287

2000 Other Work

2001 removal / relocation of utility pole unit 6 2

item unit

Quantity

No. Nadi Town Bridge Old Queens Road Bridge




18-66

18.7.2 Land Acquisition and Compensation

(1) Land Acquisition In this project, land acquisition is required for Package-1 River Widening, Package-2 Retarding basin A,B, Package-3 Ring Dike, Package-4 Surrounding Dike and Shortcuts of tributaries and Package-5 Rebuilding of Bridges. Approximate area of required land acquisition is as mentioned in Table 18-27. These area are calculated by department of land in Fiji.

Table 18-27 Land Acquisition Area

Short cut of tributaries

Land Acquisition AreaFreehold Land ha 0.00 18.66 - - - - -State Land ha 0.00 20.14 - - - - -Native Land ha #REF! 39.96 - - - - -Agricultural ha - 243.50 1.40 6.69 4.26 -Commercial ha - - - 0.36 - -Residential ha - - - 0.21 - -Others ha - - - 0.04 - -

ha 78.76 243.50 1.40 7.31 4.26 335.22Total

Breakdown by Landownership

Breakdown by Landuse

Ring DikeItem Main Works Description Unit

Unit Price(FJD)

Package-3Surrounding Dike Total

Package-1 Package-4River Widening Retarding Basin A, B

Package-2

Source: Department of Land, Fiji

(2) Compensation House relocations for river widening and construction of embankment is required in Package-1 River Widening and Package-2 Retarding Basin A,B of which number of house relocations are as shown in Table 18-27.

In addition, there are some houses in downstream which is affected negatively by the Priority Project but not affected directly. The number of affected houses is also as shown in Table 18-28.

Table 18-28 Number of house relocations and affected houses Section Number

Package-1 River Widening 6 houses (house relocations) Package-2Retarding Basin A,B 11 houses (house relocations) Ring Dike 17 houses (affected houses)


18.8 Construction Planning The components of the Priority Project (see Figure 18-41) are mainly divided into 2(two) categories such as River Works and Bridge Works. Therefore, construction scheme of execution is planned each other.

<River Works> <Bridge Works> (1)River Widening (6) Rebuilding of Nadi Town Bridge (2)Retarding Basins (7) Rebuilding of Old Queens Road Bridge (3)Surrounding Dike (4)Ring Dike (5)Shortcuts of Tributaries




18-67

S

Malakua River

⑥Rebuilding of Bridge ①River Widening: L=13km

Figure 18-41 The Components of the Priority Project (Structural Measures)

18.8.1 River Works

(1) Contents of ConstructionMain construction works of river works of the Priority Project is as mentioned in Table 18-29.

Table 18-29 Main works of river works of the Priority Project Construction Work Item Work Break down

1.Preparatory Work ・Equipment Yard ・Construction management office, Worker dormitory, electricity, Water and sewerage

2.Temporary Work ・Temporary Road, Slope ・Coffer dam, Temporary relocation of water path, Large sandbags Temporary relocation of water path, Large sandbags

3.Earth Work, Excavation ・Remove trees/roots, demolish existing structures, scrape topsoil, Excavation, disposal of waste soil

4.River Facilities 4.1 Embankment 4.2Overflow dike, Drainage Sluice, Outlet, Flood Gate, etc.

4.3Bank Protection

・Embankment, Compaction ・Main overflow dike work, front aprons, bed protection work ・Sidewall protection, crest concrete ・Main sluiceway work, flap gate work ・Concrete block bank protection ・Gabion protection

5. Subsidiary work ・Flood Water Gate

(2) Construction Section Construction work under this Project has been divided into four (4) major construction sections, some of which is divided into smaller construction sections. Construction sections are as shown in Table 18-30 and Figure 18-42. Contents of works and quantities are as previously mentioned in Chapter 18, 18.7.

Among them, a river channel widening construction of Package-1 is the largest construction, of which construction volume of excavation is 3.9 million m3. The construction plan of Priority Project is much affected by the period of construction of Package-1 so that the construction of Paccage-1 is examined in this section. The construction section Package-1 is divided into 3 sub-section, P1-1,P1-2 andP1-3 considering the location of the existing 2 bridges, location of approximately same work quantity for each sub-section.




18-68

Table 18-30 Division of Construction Section

Construction Sections Contents of Works

Major Section Break Down

Package-1

River Widening

P1-1 Downstream section of River

Widening (Nadi River：5.0~9.75k)

・River Widening (Excavation and Embankment)

P1-2 Middle stream section of River



P1-3 Upstream section of River



Package-2 Retarding Basin A,B Section ・Construction of Retarding Basin A,B

Package-3 Ring Dike Section ・Construction of Ring Dike

Package-4

Surrounding Dike

and shortcuts of

tributaries Section

P4-1 Surrounding Dike Section ・Construction of Embankment at left bank side of Nadi

River

・Construction of Embankment at right bank side of Nawaka

River

P4-2 Shortcuts of tributaries Section ・Shortcuts of tributaries

Package-5

Rebuilding of Bridge Section

・Rebuilding of Nadi Town Bridge (Namotomoto Bridge)

・Rebuilding of Old Queens Road Bridge





18-69

【Package-1】P1-1Downstream section of River

Widening (Nadi River：5.0 to 9.75k)

【Package-2】Retarding Basin A,B

Section

【Package-5】Rebuilding of Bridge Section

(Nadi Town (Namotomoto) Bridge)

Nadi Town

Nalakua River

【Package-3】Ring Dike Secion

【Package-4】P4-2Shortcuts of tributaries

Section

【Package-5】Rebuilding of Bridge Section

(Old Queens Road Bridge)

【Package-4】P4-1Surrounding Dike Section


Figure 18-42 Division of Construction Section




18-70

(3) Construction Step Construction Step of Package-1is as shown in Figure 18-43.


Figure 18-43 Construction Step

(4) Construction method and contents of each step

1) Preparatory Works and Construction Procedures to related agencies Preparation work involves making arrangements for the main construction. Whether it is done properly or not has a huge effect on the efficiency, quality, economic efficiency and schedule of the construction. It is an extremely important part of proper construction management.

When work permits are needed prior to beginning construction, procedures for related agencies must be carried out promptly with the number of days required for prior deliberations taken into account.

2) Preparatory Surveying (Groundbreaking Survey) Before construction starts, preparatory surveying is done to verify compliance with design drawings. If preparatory surveying reveals inconsistencies with design drawings, the causes of those inconsistencies will be surveyed and proper actions taken promptly.

a) Setting Water Level Markers Temporary water level markers will be set up using distance markers or the foundations of structures and

START

Preparatory Works, Construction procedures

Preparatory Surveying (Groundbreaking Survey)

Temporary Works, Finishing Stakes

Excavation Work

Embankment Work

Structures Work

Clearing Work

END

Main Works

Removing Trees/Roots, Topsoil Scraping/Excavation




18-71

other immovable objects. When such objects are not usable, temporary water level markers will be installed.

They will be set up outside of construction areas on solid ground where there is no chance that they will be

compromised by general traffic, and they require proper protection.

Positions of temporary water level markers will be determined by measuring the water level at existing

water level markers and confirming positions by referencing at least one other existing water marker;

temporary water markers cannot be placed unless this confirmation is done.

b) Setting Temporary Coordinates

Coordinate markers will be set up in addition to distance markers where necessary. As with the temporary

water level markers, they will be set up outside of construction areas. These temporary markers will be

placed upon confirming the positions of river structures and such with reference to design drawings.

Boundary markers and water survey markers will be verified before any measuring work is done. Boundary

markers may be broken, removed or become lost if there is a time lapse between work site acquisition and

start of construction, resulting in discrepancies. Thus, markers need to be verified to make sure that they are

in the correct positions. In addition, implementing agencies must be consulted and proper measures taken

before repositioning existing distance markers or water level markers when construction requires them to

be repositioned.

3) Removing Trees/Roots

Trees and roots will be removed by hand and by machine. Removed Trees and roots will be loaded into

dump trucks by hand or by backhoes (with thumbs attached) and transported to a temporary dumping area

(distance of one kilometer or less). Temporary dumping areas for Trees and roots will be set up at

one-kilometer intervals throughout construction zones. At temporary dumping areas, Trees and roots will be

fed through wood chippers, and the chips will be strewn about the slopes by machine to reuse them as

vegetation base material. Roots will be dug out by bulldozers with rippers and piled up. Roots will be

loaded into dump trucks by backhoes (with thumbs attached) and transported to temporary dumping areas.

Roots will also be fed through wood chippers, finely chopped and strewn about the slopes by machine to

reuse them as vegetation base material.

4) Topsoil Scraping/Excavation

Bulldozers will scrape the topsoil from the tops of slopes toward the bottoms efficiently (30-50 centimeters

thick). Then, the bulldozers will scrape 30-50 centimeters of topsoil from the flood channel and pile it up

every 100 meters or so along the flood channel. That dirt will be transported to dumping areas within a

distance three kilometers by wheel loaders or dump trucks. After topsoil scraping, bulldozers will excavate

again in the same order and pile up that dirt along the flood channel in the same way as in the topsoil

scraping. That dirt will be piled up every 100 meters or so along the flood channel and then transported to

embankments by wheel loaders or dump trucks. After excavation, the bulldozers will shape the slopes by

compacting them and shape the flood channel (keeping drainage in mind and making slopes drain in the

direction of the channel).

5) Finishing Stakes

Finishing stakes serve as references in the course of working on structures and must remain in place during

construction. They must be inspected regularly and verified and corrected when doubts exist.

As a rule, finishing stakes will be placed at 10-meter intervals on straight reaches of the channel and at

five-meter intervals on curved and other complicated reaches, but it is best to place them at closer intervals

when necessary.

6) Excavation Work

a) Excavation of riverbank

Excavation will be done by backhoe and soil will be loaded on dump truck and transported to embankment

point of river bank or retarding basins. When soil contains water and it is not suitable for embankment

materials, soil will be temporarily placed for drying.

If excavation will be done by bulldozers, bank excavation will be done by bulldozers from crown to foot.

The construction formation level will be excavated after slope excavation is complete. Dirt will be piled up




18-72

Dump truck(maximum pay load 11t) Wheel loader

on the construction formation level.

The elevation of construction level will be higher than average maximum sea level or the level which does not inundated in dry season and construction period including freeboard, and it is utilized as temporary construction road.

Source: JICA Study TeamFigure 18-44 Excavation Method

b) Excavation of riverbed and water way When it is difficult to excavate riverbed and waterway, excavation will be done with dry conditions and sump pit and cofferdam work with earth dike or sandbags and such will be done at the same time.

The elevation of cofferdam shall be higher than average maximum sea level or the level which does not inundated in dry season and construction period including freeboard. The elevation of cofferdam is as mentioned later in (5)2).

c) Loading and Transportation Excavated soil piled up will be loaded into dump trucks by wheel loaders. The soil will be transported to embankments or to dumping areas based on dirt transportation plans.

General disposal soil will be diverted to materials for embankment or backfilling. Transportation distance shall be within about 5km on average and impact to tourism and environment in surrounding area shall be considered because Nadi is tourism-oriented town and tourism and environment is very important. Construction temporary road will be installed with 4m width along the river or on construction formation level by utilizing the river channel widening area as temporary work space.

Source: JICA Study TeamFigure18-45 Loading and Transportation Method

7) Embankment Before building embankments, topsoil at banking locations will be scraped and banking soil prepared. Soil excavated from the vicinity will be used for embankment.

Soil transported from excavation is by dump trucks will be dumped in places where embankments are planned and compacted by bulldozers. Then, it will be re-compacted with tire rollers.

It will be rolled to a thickness of 35 centimeters and finished to a thickness of 30 centimeters, and compacted by tire roller. Embankment work will be done in approximately 50-meter segments. After soil is embanked, slopes will be shaped and compacted by backhoes as design cross section.

Bulldozer

Bulldozer

Construction Formation Level




18-73

1 lot=50～100m

Single layer

Finish thickness=30cm

Dump truck

(maximum pay load 11t)Multi-wheel roller

Embankment


Figure 18-46 Embankment Method

8) Structures Work

a) Bank Protection (Revetment for Bridge Section)

In principle, structural work will be done during dry season. Excavation of lower part than river water level

will be done by using coffer dam or large sandbags. If spring occurs, make a sump pit for drainage and it

will be drained by temporary pump.

After excavation is completed, soil will be spread to requisite dimensions and compacted. Then, riprap and

chippings will be spread if required in that order and compacted to the requisite thickness. After that,

foundation work, side flame and top flame work will be done and finally concrete block of surface will be

installed.

b) Drainage Sluice Gate, Outlet, Flap Gate and so on

i. Excavation of Foundation for Structures

As same as bank protection work, in principle, structural work will be done during dry season. Excavation

of lower part than river water level will be done by using coffer dam or large sandbags. If spring occurs,

make a sump pit for drainage and it will be drained by temporary pump.

Most excavation will be done by backhoes, and foundation excavation and leveling will be done by hand.

Open excavation will be done on slope surfaces and the bottoms of foundations will be leveled and

compacted. Then, they will be filled with riprap and chippings, compacted, and covered with blinding

concrete.

Backhoe 0.35～0.45m3

Embankment width

Embankment




18-74

Overflowlevee

Broken stone

Temporaryplacing


Sand bag

Drainage pump

Broken stone


Figure 18-47 Construction Method for Foundation of Structures

ii. Concrete Placement for Structures Concrete will be poured by chute, crane or pump truck. Ready-mix concrete will be purchased from a manufacturer in the area.

Overflowlevee

Broken stone

Temporaryplacing


Sand bag

Drainage pump

Broken stone


Figure 18-48 Construction Method for Concrete Placement

(5) Temporary Works

1) Temporary Construction Road General, primary roads will be used as construction roads, and new construction roads will also be built. Construction roads will be 4.0 meters wide within the banks of the river. Broken stone will be laid to a thickness of 20-30 centimeters to create roadbeds fully capable of supporting dump trucks.

When temporary construction road is installed in excavation area within river channel, elevation of the road is higher than the elevation which shall not be inundated during construction and shall be as same as height of temporary coffer dam which height is set as average maximum sea level in the five-year period between 2010 and 2014 (1.118m) and plus freeboard (0.5m). When temporary construction road is also used as coffer dam, width shall be 5.0m for safety. (see (5)2) and Figure 18-51)

In addition, when temporary construction road is installed in river channel, it is required to avoid an obstacle in water flow during the construction period and to be installed as required minimum size (height and width). If there is a need to be forced higher and wider, it must be removed before rainy season starts.

Steel plates will be placed as necessary to ensure traffic ability of construction roads and within construction areas.

Excavation for Structures

Temporary Earth Dike

Temporary Earth Dike

Concrete pump and mixercar

Concrete

Structure




18-75

Temporary cross-river

road

Colgate pipe Concordant discharge

Low flow channel width

When building detour roads outside of construction areas, consideration must be given such that the

construction itself is not inhibited and also that road capacity does not suffer. Implementing agencies must

be consulted to set up safety facilities and signage as the situation demands.

Dump truck

(maximum pay load 11t)

Construction road

Landside

or High water bed

Crushed stone

t=20～30cmW=4～5m


Figure 18-49 Temporary Construction Road

If necessary, corrugated pipes, large sandbags and excavation soil will be used to build construction roads

which cross the river to ensure that the river can be crossed during construction. River-Crossing roads will

be constructed and used during dry season and must be removed before rainy season starts.


Figure 18-50 Temporary Construction Road for River-Crossing

2) Temporary Coffer Dam

Temporary coffer dam will be installed when it is required to dry up to excavate riverbed and parts near

water path and construct structures under water.The temporary coffer dam must be installed during dry

season and it must be removed before rainy season. The height of it is set as average maximum sea level in

the five-year period between 2010 and 2014 (1.118m)8 and plus freeboard (0.5m). The height is set as

average maximum sea level because it is higher than highest water level in dry season in past five dry

seasons. Width of temporary coffer dam is set as 5.0m considering usage as temporary construction road for

safety.

The height of coffer dam in upstream section is to be H=1.3m including freeboard (0.5m) since the area is

not affected by tide and the maximum past water level in non-flood season is estimated approximately

0.8m.

8 In the time of the study, the mean high water spring in Lautoka in the recent five years (2010~2014) is converted to the

elevation of 1.188m ( refer to 「Draft Final Report: Main Report, Part I: Master Plan Study, Chapter5, 5.3 Current Discharge

Capacity Analysis, 5.3.1 Setting of the Conditions for the Analysis」).

t=30cm

φ2.0m etc.




18-76


Figure 18-51 Cross Section of Temporary Coffer Dam

Typical specifications of temporary coffer dam in each section are mentioned in Table 18-31. Temporary

coffer dam is installed, if required, considering construction conditions.

Table 18-31 Typical specifications and work quantity of temporary cofferdam

Crest Width 5.0 m 5.0 m 5.0 m 5.0 m

Ave.Height 3.5 m 2.5 m 1.3 m 1.3 m

Slope Gradient 1: 1.0 1: 1.0 1: 1.0 1: 1.0

Width of Bottom 12.0 m 10.0 m 7.6 m 7.6 m

Area 29.8 m2 18.8 m2 8.2 m2 8.2 m2

Transition 80 m 80 m 80 m 80 m

General section 4,750 m 4,000 m 4,750 m 5,000 m

sub total 4,830 m 4,080 m 4,830 m 5,080 m

143,693 m3 76,500 m3 39,558 m3 41,605 m3 301,355 m3

Total

Shape

Length

Eearth Volume

　　　　　Section

SpecificationsP1-1 P1-2 P1-3 P2

The mean high water spring and water level of river flow are confirmed as shown in Table 18-32.

The observed water level data of river flow without tidal effect exists only at Votualevu station (at the point

of 27.06km, during past 4 years). The maximum water level in non-flood season is estimated as El.+0.7m

at Nadi Town Bridge by applying the present riverbed gradient to the maximum water level at Votualevu

station, which is lower than the mean high water spring El.+1.118m

Table 18-32 Comparison of Mean High Water Spring and Maximum Water Level in

Non-flood Season

Distance from

Votualevu　Station

Difference

(height)

Water Level

(Maximum)

Gauge

readingElevation

Adjust

ValueL1 ⊿h1 Elevation

(m) (EL.m) (m) (m) (m) (EL.m) (EL.m)

2011 2.325 9.979 1/ 4200 ：9.83k-16.75k －－

2012 4.049 11.703 1/ 4200 ：16.75k-17.00k 0.67 ＜ 1.118

2013 3.262 10.916 1/ 1350 ：17.00k-25.00k －－

2014 0.987 8.641 1/ 630 ：25.00k-27.06k －－

Average

maximum

sea level

Nadi Town Bridge (9.83k)

Water Level (Maximum)*year

Gradient of Current Riverbed

I

Votualevu Observation Station (27.06k)

17,230 11.037.654

3) Drainage for construction works

Drainage for construction works includes draining spring water, standing water, groundwater and rainwater

at excavation sites and expansion sites in construction areas and on transportation routes. Problems with

drainage in civil engineering work carried out by machines are very closely related to the efficiency and

quality of the work, so the most up-to-date considerations must be given to draining construction areas.

Unlined drainage ditches will be dug to drain standing water and other surface water to areas outside banks.

Most situations do not call for large-scale drainage facilities; construction methods, sequences and the

progression of the schedule should account for drainage, and a flexible approach is needed to account for

the weather.

Crown

Coffer Dam

Average maximum sea level 1.118m




18-77

4) Temporary Facilities

There are two (2) types of temporary facilities; those directly related to construction and those indirectly

related.

a) Directly Related Temporary Facilities

i. Rebar/Formwork

Rebar and formwork fabrication yards are temporary facilities related to concrete. Permanent roofs must be

installed over the yards to prevent exposure to rain and sunlight.

ii. Machinery, Heavy Machinery

Repair shops for maintaining, inspecting and repairing machinery and heavy machinery are required. As

with the yards above, these shops must have permanent roofs to prevent exposure to rain and sunlight.

Particular care must be taken to set aside places to store fuels and oils used.

iii. Temporary Bridges

Temporary bridges will be built to detour traffic around bridge construction.

iv. Drainage Work

Temporary pumps will be used to drain spring water and other water that appears after cofferdams are built.

b) Indirectly Related Temporary Facilities

i. Offices, Laboratories, Storehouses, Garages

Offices, laboratories, storehouses, garages, oil and fuel storage and transformer stations will be built within

construction areas and as part of the construction schedule. Related laws and regulations will be observed

as these facilities are built. Particular care must be taken to prevent theft when handling hazardous

materials. These facilities will not be built outside the banks.

ii. Lodging

Lodging will be built to accommodate the number of workers. Care must be taken to observe related laws

and regulations and prevent pollution to the environment as these facilities are built. These facilities will

not be built near the banks.

iii. Electricity

Power supply facilities on work sites are required to provide electricity for machinery facilities,

construction lighting, water supply and drainage, cut-and-cover and office lighting.

5) Disposal Site

According to the site survey, confirmed candidates of dumping area are the following nine (9) locations.

Topsoil stripping soil occurred in excavation of river bank is transported to disposal sites and general soil is

diverted to materials for embankment and backfilling, and surplus soil is transported to disposal sites.

The disposal site is selected considering securing possibly relative wide area without residence around the

area and the lowland ,depression, low level terrace with lower level than the around ground height.

Though approx. 2.7 million m3 surplus soils are generated in this project, it is acceptable by these disposal

sites since total amount of acceptable volume becomes approx. 2.4 million m3 (h=2.0m) except proposed

town boundary area, approx. 3.0 million m3 (h=2.0m) including proposed town boundary area and approx.

3.5 million m3 (h=3.0m).

However, it is required that possibility for use as disposal site shall be reviewed with related agencies and

land owner during detailed design stage.




18-78


Figure 18-52 Proposal Area for disposal sites

Table 18-33 Acceptable total volume of disposal soil (Rough Estimation)

Area at Bottom Area at crest HeightGradient of

slopeVolume

(m2) (m2) (m) 1:n (m3)

Down stream A 76,405 74,091 1.0 75,248

76,405 71,812 2.0 2.0 148,217 (a)

76,405 69,569 3.0 218,961 (i)

Down stream B 449,776 444,057 1.0 446,916

449,776 438,370 2.0 2.0 888,146 (b)

449,776 432,716 3.0 1,323,738 (ii)

Middle stream C 210,603 206,307 1.0 208,455

210,603 202,045 2.0 2.0 412,648 (c)

210,603 197,815 3.0 612,627 (iii)

Middle stream D 174,146 170,118 1.0 172,132

174,146 166,119 2.0 2.0 340,266 (d)

174,146 162,151 3.0 504,446 (iv)

Middle stream E 165,789 162,302 1.0 164,045

165,789 158,846 2.0 2.0 324,635 (e)

165,789 155,422 3.0 481,818 (v)

Middle stream F 220,583 215,972 1.0 218,278 Proposed Town Boundary Area

220,583 211,390 2.0 2.0 431,973 (f)

220,583 206,836 3.0 641,129

Upstream G 71,378 68,473 1.0 69,925

71,378 65,598 2.0 2.0 136,976 (g)

71,378 62,754 3.0 201,198 (vi)

Upstream H 94,047 91,437 1.0 92,742 Proposed Town Boundary Area

94,047 88,861 2.0 2.0 182,908 (h)

94,047 86,319 3.0 270,549

Upstream I 69,718 67,021 1.0 68,369

69,718 64,364 2.0 2.0 134,082 (i)

69,718 61,748 3.0 197,200 (vii)

2.0 2.0 2,384,970 =(a+b+c+d+e+g+i), except Proposed

Town Boundary Area

2.0 2.0 2,999,851 =(a+b+c+d+e+f+g+h+i), including

Proposed Town Boundary Area

3.0 2.0 3,539,988 =(i+ii+iii+iv+v+vi+vii), except

Proposed Town Boundary Area

Remarks

Total Amount

Right bank side of

Nadi River

Right bank side of

Nadi River

Right bank side of

Nadi River

Right bank side of

Nadi River

Left bank side of

Nadi River

Right bank side of

Nadi River

Left bank side of

Nadi River

Left bank side of

Nadi River

Left bank side of

Nadi River

Area Left/Right

Embankment shape of surplus soil


Upstream I Upstream G

Middle stream H

Middle stream E

Middle stream D

Middle stream F

Middle stream C

Downstream B

Downstream A




18-79

“Proposed Town Boundary Area” is the area where is the expansion area of town by Nadi town and there is a possibility that the land-use planning and the like have been made newly. Therefore, it shall be reviewed with related agencies and land owner during detailed design stage

Source: Nadi Town Council

Figure 18-53 Boundary of Nadi Town (Existing and Proposed)

(6) Work Schedule

1) Construction Step for river widening Construction time scheduling of Package-1 River Widening is studied because its construction quantity is huge and largest and it becomes critical factor in time schedule of implementation of this project. It should be noted that constructions of others of the Package-2 to 5 is carried out at the same time in parallel with Package-1.

River widening will be done through a whole year by changing the earth work contents such as excavation parts and height in dry season and rainy season. Rainy season is assumed to December to March and during rainy season, the excavation of river bank which elevation is higher than average maximum sea level 1.188m will be done. Safety shall be considered highly enough during rainy season construction. During dry season, the excavation of river bank which elevation is lower parts using cofferdam will be done. In case that excavation is done by backhoe on coffer dam but backhoe reach is insufficient, it is required that excavation shall be done by dredger or dry up by coffer dam, which will be reviewed during detailed design. In case that coffer dam is required, coffer dam shall be installed following the specifications previously mentioned in (5)2). Coffer dam is installed during dry season and it must be removed before rainy season. Construction step is as described in Figure 18-54 and 18-55.

Embankment is constructed through whole year, but be careful so as not to interfere with other construction works such as excavation.




18-80

Figure 18-54 Construction Step (1)

＜Shut up river water by using coffer dam＞

STEP-3 Completion

Embankment EmbankmentStep-1: Inatallation of Coffer Dam

Step-2: Excavation

▽(1.118m)+0.5m (freeboard)

Embankment Embankment


Step-4: Removal of Coffer Dam

Step-3: Excavation

Figure 18-55 Construction Step (2)

STEP-0 Current Condition

STEP-1 Rainy Season

STEP-2 Dry Season

＜Shut up river water by using excavation parts＞

Current Cross Section

Excavation Area higher than the average

maximum sea level in the five-year

period between 2010 and 2014 (1.118m)

▽Average maximum sea level in the five-year period between 2010 and 2014 (1.118m)+0.5m (freeboard)


Step-1: Excavation

lower part of slope

Step-2: Removal of

temporary coffer dam

Utilization as

temporary coffer dam



Leave water side part to utilize

it as temporary coffer dam




18-81

2) Planning Conditions

a) Increase coefficientof workable days

The increase coefficient of workable day is assumed as constant through year considering non-workable

days such as holidays and suspended day by rainfall which is estimated by the rainfall data during recent 5

years.

Daily rainfall at Nadi Airport Observation Station where is nearest to the construction area in the last past

five years is summarized as mentioned in Table 18-35. Using these rainfall volume and number of rainfall

days, suspended days by rainfall are calculated by using the ratio mentioned in Table 18-34. In addition, by

adding the number of holiday in a year, total suspended days are calculated in a year. Increase coefficient of

workable days is 1.7 through a year.

Table 18-34 Suspended days (ratio) by rainfall Works Suspended Days due to Rainfall

Rainfall (mm) Main Works

0 0.00

0-5 0.00

5-10 0.75

10-15 0.75

15-20 0.75

20-25 1.00

25-30 1.00

30- 1.50 Source: JICA Study Team The above table of values are set taking into

consideration other of yen loan similar projects,

weather condition and labor situation in Fiji.

Table 18-35 Calculation of increase coefficient of workable days

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0 13.6 8.2 10.2 16.2 20.2 24.0 26.4 23.4 21.2 19.4 14.4 12.4

0-5 6.4 8.0 9.4 6.6 7.2 2.0 2.8 5.6 4.8 6.6 8.6 8.0

5-10 2.2 3.4 4.2 1.8 0.8 1.0 0.8 0.6 0.6 1.4 1.4 3.2

10-15 1.8 1.8 0.8 1.4 0.6 0.6 0.0 0.0 1.0 0.8 1.8 2.2

15-20 1.0 1.4 1.0 1.2 0.0 0.6 0.0 0.2 0.8 0.6 0.6 1.6

20-25 1.8 0.6 1.0 1.0 0.6 0.0 0.0 0.6 0.6 1.0 0.8 0.2

25-30 0.2 0.8 0.6 0.2 0.0 0.4 0.4 0.2 0.2 0.4 0.2 0.6

30- 4.0 4.0 3.8 1.6 1.6 1.4 0.6 0.4 0.8 0.8 2.2 2.6

Total Days of Month 31.0 28.2 31.0 30.0 31.0 30.0 31.0 31.0 30.0 31.0 30.0 30.8

Rest by Rain 11.8 12.4 11.8 6.9 4.1 4.2 1.9 2.0 3.8 4.7 7.2 10.0

Rest Days by Rain 12 13 12 7 5 5 2 2 4 5 8 10

Sunday 4 4 4 4 4 4 4 4 4 4 4 4

National Holiday 2 0 0 3 0 1 0 0 0 1 1 2

18 17 16 14 9 10 6 6 8 10 13 16

13 11.2 15 16 22 20 25 25 22 21 17 14.8

2.4 2.5 2.1 1.9 1.4 1.5 1.2 1.2 1.4 1.5 1.8 2.1 1.7

2.3 1.5 Rainy Total

Coefficient for cariculation of

work days Dry Season Avarage: Rainy Season Avarage:

Suspended by

Rain

Suspended by

Holiday

Suspended Days

Woekable Days

Average Days in 5 year (2009-2013)Rainfall (mm)

Category


b) Working hours per day

Working hours per day is set as an eight‐hour day.

c) Assumed Heavy Equipment and Daily Construction Execution Volume

Heavy equipment is selected referring to civil engineering cost estimation criteria, Ministry of Land,

Infrastructure, Transport and Tourism. Selected heavy equipment is mentioned in Table 18-36 considering

construction volume and construction condition.




18-82

[Selection of Heavy Equipment]

Machine Main Works Suitable Construction Volume Specifications, Class Daily Construction

Execution Volume

Bulldozer Excavation and dozing Less than 30,000m3 20t class 320m3 More than 30,000m3 32t class 710m3 Backhoe Excavation and Loading Less than 50,000m3 Piled 0.8m3(Flat piled 0.6) 300m3 More than 50,000m3 Piled 1.4m3(Flat piled 1.0) 500m3 Source: Civil engineering cost estimation criteria, Ministry of Land, Infrastructure, Transport and Tourism

Table 18-36 Selected Heavy Equipment

Construction Section Heavy Equipment

Bulldozer Backhoe P1：River Widening 32t class

Daily Construction Execution Volume: 710m3

Piled 1.4m3(Flat piled 1.0)) Daily Construction Execution

Volume: 500m3 P2：Retarding Basin A,B 32t class


Piled 1.4m3(Flat piled 1.0) Daily Construction Execution

Volume: 500m3 P3：Ring Dike 20t class



Volume: 300m3 P4-1：Surrounding Dike of Nadi Town 20t class



Volume: 300m3 P4-2：Shortcuts of tributaries 20t class



Volume: 300m3

In the above table, although daily construction execution volume of 32t class bulldozer is 710m3, it becomes possible by supported by a 1.4m3 class backhoe and 0.8m3 class backhoe in the actual site. In the construction planning at detailed design stage, pay attention to these combinations.

3) Work Schedule Calculation result of construction period of Package-1 is as shown in Table 18-36 and those of other packages are also shown in Table 18-37.

Though total construction period depends on the number of input (number of equipment), in Package-1 which construction volume is the largest, six parties each of the heavy machinery of the combination (bulldozer 32t class, backhoe 1.4m3 and 0.8m3 class) for each left bank side and right bank side is required and it takes approx. four (4) years to complete civil works in case of that condition. In addition, it is required two (2) backhoes (0.8m3 class) for coffer dam.

Work schedule is as described in Table 18-38.




18-83

Table 18-37 Construction Period (River Work)

Day Month

(m3/日) (m3) (days) (days) (month)

P1-1

Installation of Coffer

Dam600 143,693 3 80 1.7 136.0 4.5

Removal of Coffer

Dam600 143,693 3 80 1.7 136.0 4.5

Excavation 710 1,781,637 12 210 1.7 357.0 11.9

Embankment and

Backfilling320 424,593 6 222 1.7 378.0 12.6

P1-2


Dam600 76,500 3 43 1.7 74.0 2.5

Removal of Coffer

Dam600 76,500 3 43 1.7 74.0 2.5

Excavation 710 1,218,717 12 144 1.7 245.0 8.2

Embankment and

Backfilling320 276,153 6 144 1.7 245.0 8.2

P1-3


Dam600 39,558 6 11 1.7 19.0 0.6

Removal of Coffer

Dam600 39,558 6 11 1.7 19.0 0.6

Excavation 710 927,827 12 109 1.7 186.0 6.2

Embankment and

Backfilling320 496,517 6 259 1.7 441.0 14.7

P2Installation of Coffer

Dam600 41,605 6 12 1.7 21.0 0.7

Removal of Coffer

Dam600 41,605 6 12 1.7 21.0 0.7

Excavation 710 1,257,035 5 34 1.7 58.0 1.9

Embankment and

Backfilling320 1,159,681 4 87 1.7 148.0 4.9

P3 Excavation 320 6,446 2 3 1.7 6.0 0.2

Embankment and

Backfilling300 78,970 2 37 1.7 63.0 2.1

－－－－－－

P4-1 Excavation 320 290,737 2 51 1.7 87.0 2.9

Embankment and

Backfilling300 285,614 2 53 1.7 91.0 3.0

－－－－－－

P4-2 Excavation 320 23,431 2 37 1.7 63.0 2.1

Embankment and

Backfilling300 27,725 2 47 1.7 80.0 2.7

－－－－－－－

Number of

Equipments

(Nos)

Package SectionMain Earth

Works

Construction

Execution

Volume

Construction

VolumeWork Day

Ratio

Construction Period

Ring Dike

P4

Surrounding

Dike &

Shortcut

Surrouding Dike of

Nadi Town

Shortcuts of tributaries

P1

River

Widening

P2

Retarding

Basin

P3

Ring Dike

River Widening in

downstream section

River Widening in

middle stream section

River Widening in

upstream section

Retarding Basin A,B





18-84

Table 18-38 Work Schedule（River Work）

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

(day) (Month) 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30 10 20 30

P1-1

河道拡幅下流工区

Preparation 30 1.0

Access Road 30 1.0

272 9.1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Earth Work Excavation 357 11.9 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Embankment 378 12.6 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

180 6.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

P1-2

河道拡幅中流工区

Preparation 30 1.0 1 1 1

Access Road 30 1.0 1 1 1

148 4.9 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Earth Work Excavation 245 8.2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Embankment 245 8.2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

180 6.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

P1-3

河道拡幅上流工区

Preparation 30 1.0 1 1 1

Access Road 30 1.0 1 1 1

38 1.3

Earth Work Excavation 186 6.2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Embankment 441 14.7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Structures 180 6.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

Preparation 30 1.0

Access Road 30 1.0

42 1.4 1 1 1 1

Earth Work Excavation 58 1.9 1 1 1 1 1 1

Embankment 148 4.9 1 1 1 1 1 1 1 1 1

270 9.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

Preparation 30 1.0

Access Road 30 1.0

Earth Work Excavation 6 0.2 1

Embankment 63 2.1 1 1 1 1 1 1 1

90 3.0 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

Preparation 30 1.0

Access Road 30 1.0

Earth Work Excavation 87 2.9 1 1 1 1 1 1 1 1 1

Embankment 91 3.0 1 1 1 1 1 1 1 1 1 1 1

270 9.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

Preparation 30 1.0

Access Road 30 1.0

Earth Work Excavation 63 2.1 1 1 1

Embankment 80 2.7 1 1 1 1 1

180 6.0

Clearing 30 1.0 1 1 1

Pack

ag

e

Section Main Work Item

Construction

Periond

1 year 2 year 3year 4year

Coffer dam (Installation & Removal)

Structures


Riv

er

Wo

rk

P1

Riv

er W

iden

ing


Structures

Structures

P4-2

Structures

Structures

P3

Rin

g D

ike P3

Structures

P2

Reta

rdin

g B

asi

n P2

Coffer dam

P4

Su

rro

un

din

g D

ike &

Sh

ort

cu

t

P4-1

Dry Season Dry SeasonDry Season Dry Season

Drainage Suluice Gate Overflow Dike

Fabrication of Flood Wall Gate Installation of Flood Wall Gate

Flap Gate for drainage

Flap Gate for drainage and small river


Rainy Season Rainy Season RainyRainy Season Rainy Season




18-85

(7) Disposal Planning In this project, approx. 2.7 million m3 disposal soils from Package-1 and approx. 100 thousand m3 disposal soils will occur. Excavation is main work of this project and it is required that disposal soils are properly transported and treated within construction period. Proposed disposal sites and capacity is previously mentioned in (5)5).

In this clause, disposal days and number of dump tracks required is roughly calculated. Prior to the calculation, these conditions are set as preconditions.

a) Preconditions Dump truck will be selected as transportation machine. 10t to 15t class dump truck is applied in and around residential area and 32t class dump truck is applied in and around suburban area considering efficient transportation. (Necessity of dredger is also considered at the detailed design stage)

Disposal sites are to be selected most closest one from each construction section as mentioned in Table 18-39 and disposal soils are transported by routes as described in Figure 18-56.

Construction temporary road is installed along the river or in the excavation area as previously mentioned in (5)1). In addition, since river water level is low during dry season, if possible, a river crossing road as previously described in (5)1) in order to increase transportation efficiency (to shorten transportation distance and time) and to mitigate impact surrounding environment. In this case, the transport distance is 5km or less from each section.

Table 18-39 Disposal Sites Construction

Section Disposal Sites Acceptable volume for disposal

P1-1 Downstream A, B Total 1,000,000m3 (h=2m) P1-2 Middle stream C, D, E, F, H Total 1,900,000m3 (h=2m, 3m) P1-3 Middle stream C, D, E, F, H P-2 Upstream G,I Total 230,000m3 (h=2m)

It is assumed that dump trucks are to be waited for each party in each construction section and a few dump trucks are to be waited in each party.




18-86

【Package-1】P1-3Upstream sectionof River Widening (Nadi River：14.0

to 18.75k)

B

【Package-1】P1-1Downstream section of River

Widening (Nadi River：5.0 to 9.75k)【Package-2】

Retarding Basin A,B Section

【Package-1】P1-2Middle stream section of River

Widening (Nadi River：10.0

to 14.0k)

A

C

F

D

E

G

H

I

A～IDisposal Site

Transportation Route in the rivearea or along the riverside

Transportation Route onexisting road


Figure 18-56 Routes of Disposal Transportation




18-87

b) Disposal days and number of dump tracks

Number of days and dump trucks required for disposal based on above preconditions are calculated and

result of them is as mentioned in Table 18-40.

Table 18-40 Number of Transportation Days and Dump Trucks for Disposal

P-1 River Widening

2,700,000 m3

981,818 m3 785,455 m3 932,727 m3 2,700,000 m3

32 t 15 t 32 t

1.8 t/m3 1.8 t/m3 1.8 t/m3

17.8 m3 8.3 m3 17.8 m3

55,159 nos 94,634 nos 52,401 nos 202,194 nos

12 party 12 party 12 party

2 nos 2 nos 2 nos

144 nos/day 144 nos/day 144 nos/day 432 nos/day

383.0 days 657.2 days 363.9 days 1,404.1 days

12.8 months 21.9 months 12.1 months 46.8 months

1.1 years 1.8 years 1.0 years 3.9 years1)

Amount of disposal soils are divided propotionally by section distance ratio

P-2 Retarding Basin A, B

100,000 m3

100,000 m3 100,000 m3

10 t

1.8 t/m3

5.6 m3

17,858 nos 17,858 nos

5 party

2 nos

60 nos/day 60 nos/day

297.6 days 298 days

9.9 months 10 months

0.8 years 1 years1) Amount of disposal soils are divided propotionally by section distance ratio

Number of Working Dump Truck per day ― ―

Requied Days for Disposal

― ―

― ―

― ―

Number of Party ― ― ―

Number of Dump Truck per party ― ― ―

Time required for a round-trip incl. work 0.33 hr +1.0hr = 1.33 hr ― ― ―

Number of round-trip per day 8 hr ÷ 1.33 = 6.01 → 6 times ― ― ―

―

Time for loading and unloading 1.0hr ― ― ―

Total number of Dump Trucks ― ―

Time required for a round-trip 5km/30(km/hr)*2=0.33 hr ― ―

Dump truck load capacity ― ― ―

―

Class of Dump Truck ― ― ―

Unit volume weight of the soil ― ― ―

Disposal Planning Total

Total Disposal Volume ―

Disposal Volume

in each section1)

P2 ― ― ―

―

Number of Party ―

Number of Dump Truck per party ―

Number of Working Dump Truck per day

Requied Days for Disposal

Time required for a round-trip incl. work 0.33 hr +1.0hr = 1.33 hr ―

Number of round-trip per day 8 hr ÷ 1.33 = 6.01 → 6 times ―

Total number of Dump Trucks

Time required for a round-trip 5km/30(km/hr)*2=0.33 hr ―

Time for loading and unloading 1.0hr ―

Class of Dump Truck ―

Unit volume weight of the soil ―

Dump truck load capacity ―

Disposal Planning Total

Total Disposal Volume ―

Disposal Volume

in each section1)

P1-1 P1-2 P1-3 ―

River Flow




18-88

18.8.2 Bridge Works

(1) Nadi Town Bridge The outline of construction process of Nadi Town Bridge is as shown as follows. At first for the present traffic, the detour including temporary bridge is secured in the downstream of the existing bridge. After remove the existing superstructure of the existing bridge from on the bridge, the river water is diverted to prepare construction yard in the river. Then the exiting substructure is demolished and new substructure is constructed. The superstructure can be constructed by election girder method in spite of flood season from the election yard kept on the right bank.

The followings are taken care in the construction work. A1 Abutment is located adjacent to the urban area and A2 Abutment is adjacent to the residential houses and primary school as the local condition of Nadi Town Bridge. The traffic volume of Queens Road, which the concerning bridge is located, is quite heavy because of primary road in the region. The area of bridge construction is a tidal river section.

Hereunder, the flow of bridge rebuilding, principle of construction at each step, and typical construction period are explained considering the above-mentioned site conditions.

1) Construction Process The construction process flow of this bridge is shown in Figure18-57. River improvement work is under planning at the bridge rebuilding location but it is implemented separately from this bridge because of excessive length.

Figure 18-57 Construction Flow（Nadi Town Bridge）

START

Temporary Bridge / Detour

Removal of Superstructure

River flow diversion / inside work yard

Removal of piers

Removal of foundation

Construction of foundation

Construction of piers

Construction of superstructure

Removal of Temp. Brdg./ Detour

E N D

Temporary bridge should be arranged at the lower stream side due to the site condition.

Utilities (waterworks, sewage pipe, phone, and telecom) along the existing bridge should be relocated to temporary bridge.

Removal of superstructure should be carried out from bridge slab.

Rebuilding work

One side on either bank of river should be diverted, existing substructure is removed, and new substructure is built. After that, opposite side of bank is built continuously.

Removal Work

Newly constructed PC Post-Tension T girders should be done by method of girder installation with erection beam.




18-89

STEP-1: Temporary Bridge, Detour, Removal of existing Superstructures

STEP-2:Construction of New Abutments

STEP-3: Removal of existing Abutments




18-90

STEP-4: Diversion of River Water, Preparation of Work Yard at Right River Bank

STEP-5: Removal of existing Pier (P3)

STEP-6: Reconstruction of new Pier (P3)




18-91

STEP-7: Revetment for River Right Bank

STEP-8: Transition of River Flow / Preparation of Work Yard at Left River Bank

STEP-9: Removal of existing Pier (P1 & P2)




18-92

STEP-10: Reconstruction of New Pier P1

STEP-11: Revetment for River Left Bank / Removal of Work Yard

STEP-12: Construction of new Superstructure / Removal of Temporary Bridge and Detour

Figure 18-58 Construction Step (Nadi Town Bridge)




18-93

2) Temporary Work Plan The detour route to secure the current traffic is selected as shown in Figure 18-59.

Figure 18-59(1) 58Detour Route (Nadi Town Bridge)

The road width of detour route is set up as shown figure below considering the existing bridge cross section. A width of temporary bridge is same as present bridge as shown in Figure 18-59(2)

Figure 18-59 (2) Detour Planning (Nadi Town Bridge)

Formation level of work yard is taken

as H.W.+1.0m.

A1

A2

Residential Area

Existing Road(Photo18-3)

Construction Yard

Detour

Construction Yard

Primary School

Photo18-3 Existing Road at Left Bank

Current Condition (View from A1 side)

2000 6000

3000 3000 [Pedestrian] [Carriage Way]

8000

Width of Detour and Temporary Bridge

Road Width of Existing Bridge (after Investigation) Example of Temporary Bridge




18-94

3) Removal Plan of Existing Bridge The structural dimension of existing bridge is summarized in Table 18-41 and the bridge general drawing is shown in Figure 18-60 Since the As-Built drawings are not obtainable; confirmed numeric values by the site investigation are shown in the drawing.

Table 18-41 Structural Dimension of Existing Bridge（Nadi Town Bridge）

Item Dimension / Description

Bridge Length L=72.800m

Span Division 18.4m+23.3m+17.8m+13.8m

Width 10.390m (Both Side Pedestrian, W=1.7m)

Type of Bridge Steel 3-span Gerber Girder Bridge + Steel Simple Span Bridge

Type of Substructures

Reversed T type Abutment (assumed), Pile Bent Pier *type and size of foundation is unknown

Completion February 1965




18-95

Figure 18-60 General Drawing of Existing Bridge（Nadi Town Bridge）




18-96

Basic plan and principle for removal of superstructure, substructure and foundation of existing bridge are shown below.

a) Removal of Superstructure Superstructure is removed by the crane which installed on bridge deck (Figure 18-61).

The removal works are basically carried out by 3 steps; 1. Handrails and Accessories, 2. Bridge Slabs, 3. Primary Girders

The bridge slab and primary girder will be removed being divided into pieces at points of welding, Gerber Hinges and supports to reduce the size of heavy equipment, consideration of surrounding environment, constructability and safety concerning.

Removal work is carried out from A1 side between A1 and P1 (till Gerber Hinge) due to narrow work space at A1 side. Removal work between P1 and A2 is carried out from A2 side.

Each removal section repeats “bridge slab removal primary girder removal next section removal”.

Bridge slab is cut and divided into pieces by concrete cutter, and then removed and carried out.

Temporary Bent will be installed when primary girder is removed if necessary in order to secure safety. Each support and connection at Gerber Hinge will be divided by cutter in advance to primary beam removal.

Figure 18-61 Removal Plan of Superstructure (Nadi Town Bridge)

6 1

Removal& Carry out to A2 Side

5 2 3 4

1 2 3 456

Removal& Carry out to A1 Side

N Sequence of removal

N Placement of crane at removal

Gerber Hinge




18-97

b) Removal of Substructures and Foundations

For removal of existing abutment, approach to the abutment should be from rear side of abutment and (1) base excavation, (2) removal of structural body, (3)removal of pile foundation, (4) backfill are carried out in turn.

Temporary access road to river bed is prepared before removal of piers. Basic conditions of access road and routes are shown below. (Figure 18-62).

width:4.0m(carriage way 3.0m, shoulder 0.5m)

vertical incline: 10% (for consideration of heavy equipment)

Piers should be removed after one side of river bank is dried by cofferdam using sand bags etc., as mentioned in Clause 1) above. New substructure is reconstructed within the cofferdam after the existing substructure is removed.

The formation height of embankment elevation is set up as H.W. +1.0m. The formation setting is shown in 18.8.1(5)2）. This section is tidal area so that the mean high water springs is higher than the water level of river flow (estimation value) in non-flood season. The structural body of substructure is removed by demolition by giant breaker and transportation.

The existing pile foundation should be basically pulled out and removed but may be cut off below the formation level of river bank if removal is difficult.

4) Construction Plan of Substructures The plan of new substructure and foundation is shown in Table 18-41 and the general drawing for rebuilt bridge is shown in Figure 18-63.

Table 18-42 Plan of new Substructure and Foundation (Nadi Town Bridge)

Item Type Remarks

Abutment Inverted T Refer to18.6.2(3)4)a)

Pier Wall Refer to 18.6.2(3)4)b)

Foundation Cast-in place Pile Refer to 18.6.2(3)5)

Construction Road

(A1 Side)

A1

A2Construction Road

(A2 Side)

Detour

Figure 18-62 Access Road Plan (Nadi Town Bridge) Source: JICA Study Team




18-98

Figure 18-63 General Drawing of New Bridge (Nadi Town Bridge)




18-99

The type of foundation should be Cast-in-Place Concrete Pile as mentioned above, and be constructed (1) installation of outer steel casing (by Diesel Hammer method, Figure 18-64), (2) earth excavation within the casing, (3) installation of reinforcing bar cage, (4) concrete casting, in turn.

Figur

Figure 18-64 Example of Pile Construction (Pile driving by Diesel Hammer) Source: provided by local contractor

Reversed T type Abutments and Wall type Piers are planned, and these are constructed; (1) base excavation, (2) footing construction, (3) construction of structural body, (4) backfill, in turn after the construction of pile foundation.

Concrete is cast in place by Chute in case of close distance, and by Crane in case of long distance or high place, and by Concrete Pump & Mixer in case of long distance & large quantity.

5) Erection Plan of Superstructure Erection plan of superstructure is summarized in Table 18-43.

Table 18-43 Superstructure Reconstruction Plan (Nadi Town Bridge)



Span Division [email protected]

Width 13.000m (Both Side Pedestrian, W=1.5,3.0m)

Type of Bridge PC-3span Continuous Post Tension T Girder Bridge

Erection Method Girder Installation by Erection Beam

The method of girder installation by erection beam is employed for reconstruction of superstructure because this bridge is river crossing bridge and also it is difficult to install the girder below the existing beams. (Figure 18-65）.




18-100

Figure 18-65 Example of Girder Installation by Erection Beam

(Left: Girder Fabrication at Work Yard on site, Right: Installation of Girder by Erection Beam)

Source: provided by local contractor

Fabrication of primary girders is planned at the work yard which can be secured behind the A2

Abutment.

Superstructure is erected in turn as; (1) site survey (confirmation of as-built substructure), (2)

installation of supports, (3) temporary rail laying, fabrication of erection beams, (4) fabrication of

primary girders, (5) installation of erection beams, (6) pull-out of primary girders, (7) primary

girder setting (repeat (4)~(7) as same nos. to girders), (8) move erection beam to next span

(repeat (4)~(8) as same nos. to span), (9) removal of erection beams, (10) transverse beams,

bridge slab (refer to Figure 18-66).

The election girder method is that PC girder fabricated in the back yard of abutment is moved by

pre-installed election girder and shifted laterally and installed to the scheduled position by the

hanging girder device. Therefore the temporary works such as temporary support which block

river cross section is not required and the election work can be done above water level so that

construction can be done through a year.

When bridge slab is reconstructed, utilities should be restored.

Vehicle and pedestrian traffic by detour passing should be returned to new bridge after the

superstructure is completed, and then the temporary bridge is removed.




18-101

PLAN VIEW

Anchor for Leg

Anchor Fitting

PC steel bar

Leg Support Bracket

Anchor for Leg

Dolly

Erection Girder

Tifor

Portal Lifting Equipment

Hanging Girder Fitting

Chain Block

Trolley

Leg Support Bracket

SIDE VIEW

PLAN VIEW

Track rail Segment Dolly Dolly

Segment Connecting Yard

Erection Girder

Hanging Girder Device

Strut Wire

Anchor for Strut

Wire

Hanging Girder Device

Strut Wire

Launching Machine

Segment Connecting Yard

Erection Girder

Erection Girder

Launching Machine

Launching Machine

Center Distance of Hanging Girder Device

Figure 18-66 Example of Supere

Structure Election

Cross Section of A1 Bracket of A1 Abutment PLOT PLAN of Leg Support

Bracket of A1 Abutment

CROSS SECTION VIEW




18-102

6) Process Scheduling

The outline of construction schedule is as shown in Table 18-44. The substructure in the present river

channel is to be constructed in dry season. The superstructure is constructed by the election girder method

over the water surface and from behind of abutment so that the construction can be done through a year.

Table 18-44 Process Scheduling (Nadi Town Bridge)

1 2 3 45 6 7 8 9 10 11 121 2 3 4 5 6

Clear Works

Temporary

Bridge3

MItem

Removing

Temporary Bridge1.5

1st Year 2nd Year 3rd Year

Preparatory

Works

Detour

Removing Existing

Superstructure

7 8 9 10

24 25 26 27 28 2914 15 16 17 18 19

1

10

0.5

0.5

3 4

0.5

2.5

1

1

4

2

1

1

1

2.5

34 35 36

Abutments

Works

Removing

Existing Abutments

Coffering Works

1 2 3 4

30 31 32 33

Removing

Existing P3 Pier

Construction

P2 Pier

5 6 7 8

Revetment Works

Right Bank

Coffering Works

9 10 11 1211 12

1

1

1 2 20 21 22 235 6 7 8 13

Revetment Works

Left Bank

Superstructure

Erection Works

Removing

Detour

9 10 11 12

Removing

Existing P1 & P2 Pier

Construction

P1 Pier

Dry Season Dry SeasonDry Season





18-103

(2) Old Queens Road Bridge The outline of construction process of Queens Road Bridge is as shown as follows. At first for the present traffic, the detour including temporary bridge is secured in the downstream of the existing bridge. After remove the existing superstructure of the existing bridge from on the bridge, the river water is diverted to prepare construction yard in the river. Then the exiting substructure is demolished and new substructure is constructed. The superstructure can be constructed by election girder method in spite of flood season from the election yard kept in west side (A1 abutment side). The tram line bridge is elected by crane from the road bridge surface.

The followings are taken care in the construction work. A2 Abutment of Old Queens Road Bridge is located adjacent to the cement factory and private houses along the existing road, and the Old Nadi Back Road, where this bridge is placed, is the primary road of this region. The Road is taking function to connect Queens Road and Nadi Back Road; the traffic volume is much. Hereunder, the flow of bridge rebuilding, principle of construction at each step, and typical construction period are explained considering the above-mentioned site conditions.

1) Construction Process The construction process of this Road Bridge and Tramline Bridge, are shown in Figure 18-67 and

18-68.


Figure 18-67 Construction Flow（Old Queens Road Bridge）

START

Temporary Bridge / Detour

Removal of Superstructure

Preparation of access road into river bed

Removal of piers

Removal of foundation

Construction of foundation

Construction of piers

Construction of superstructure

Removal of Temp. Bridge/Detour

E N D

Temporary bridge should be arranged at the lower stream side due to the site condition.

Utilities (waterworks pipe, phone, and telecom) along the existing bridge should be relocated to temporary bridge. Removal of superstructure should be carried out from bridge slab; Tramline Bridge first and Road Bridge second.

Rebuilding work

Removal and rebuilding of substructure should be carried out basically in dry season (April ~ November). Average river water level at work place in dry season is low (result of monitoring), removal of existing bridge should be carried out after drain pipes are installed at water flow area and after preparation of work yard.

Removal Work

Newly constructed PC Post-Tension I girders for Road Bridge should be erected by method of girder installation with erection beam. After Road Bridge is completed, the steel girder for Tramline Bridge is erected by crane on this bridge slab.

(1) Tramline Bridge (2) Road Bridge

(1) Road Bridge (2) Tramline Bridge




18-104

STEP-1: Temporary Bridge, Detour, Removal of existing Superstructures

STEP-2: Removal of existing Abutments and Reconstruction of new Abutments

STEP-3: Arrangement of Access Road into Rive




18-105

STEP-4: Removal of existing Piers (P3~P6)

STEP-5: Reconstruction of New Piers (P1~P2)

STEP-6: Removal of existing Piers (P1, P2, P7, P8), Construction of Revetment




18-106

Figure 18-68 Construction Step Flow (Old Queens Road Bridge)

STEP-7: Removal of Access Road

STEP-8: Reconstruction of Superstructure (Road Bridge, Tramline Bridge), Removal of Temporary Bridge and Detour Road




18-107

2) Temporary Work Plan The detour route to secure current traffic and Tramline is selected as shown in Figure 18-69.

Figure 18-69 Detour Route (Old Queens Road Bridge) The road width of detour route is set up as shown below figure considering the existing bridge cross section. A width of temporary bridge is same as present bridge as shown in Figure 18-70.

Figure 18-70 Detour Planning (Old Queens Road Bridge)

Current Condition (View from A2 side)

Road Width of Existing Bridge (after Investigation)

Width of Detour and Temporary Bridge

8000

1000 3000 1500 1500 [Footpath] [Traffic Lane] [Allowance] [Tramline]

5000 3000

Example of Temporary Bridge

Photo18-4 Private House at Right BankA1

A2

Cement Plant

Private House

Construction Yard for Superstructure

Detour (Road)

Private House

Detour (Tramline)

Bus Company




18-108

3) Removal Plan of Existing Bridges The structural dimension of existing bridge is summarized in Table 18-45 and the bridge general drawing is shown in Figure 18-71. Since the As-Built drawings are not obtainable; confirmed numeric values by the site investigation are shown in the drawing.

Table 18-45 Structural Dimension of Existing Bridge (Old Queens Road Bridge)



Span Division [email protected]+12.1m+12.3m+9.3m

Width Road Bridge 3.05m(Carriageway)+1.1m(Overhang Sidewalk)

Tramline Bridge 0.93m

Type of Bridge

Road Bridge 9span Steel Girder Bridge (RC Bridge Slab)

Tramline Bridge 9span Steel Girder / Slab Continuous Bridge

Type of Substructures Single line pile Abutment (assumption), Pile-bent type Pier, Foundation type: RC Pile (300x300),length is unknown

Completion 1936 Source: JICA Study Team




18-109

Figure 18-71 General Drawing of Existing Bridge (Old Queens Road Bridge)

River Flow

River Flow




18-110

Basic plan and principle for removal of superstructure, substructure and foundation of existing bridge are shown below.

a) Removal of Superstructure Superstructure is removed by the crane which installed on bridge deck of Road Bridge. The work space is secured by installation of H columns & covering plate after the curb of Road Bridge is cut out preliminary, because the out-rigger of crane cannot be extended due to the narrow road width of 3.05m.

Removal work is carried out from A2 toward A1 in one-way because the entrance of cement factory and private houses are adjacent to the bridge at backside of A2 Abutment (see Figure 18-72).

The removal works are basically carried out by 5 steps; 1. Sidewalk on the over-hang beam, 2. Bridge Slab of Tramline, 3. Primary Girder of Tramline Bridge, 4. Bridge Slab of Road Bridge, 5. Primary Girder of Road Bridge

Connection points at support of each substructure are preliminary cut and divided into pieces by concrete cutter.

Bridge slab and primary girders (transverse) are divided by slab cutter in advance because of size reduction of heavy equipment, and then removed and carried out.


Figure 18-72 Plan for Removal of Superstructure (Old Queens Road Bridge)

b) Removal of Substructure and Foundation

For removal of existing abutment, approach to the abutment should be from rear side of abutment and (1) base excavation, (2) removal of structural body, (3) removal of pile foundation, (4) backfill, are carried out in turn.

Temporary access road to river bed is prepared before removal of piers. Average river water level at work place is low, removal for substructure & foundation of existing bridge should be carried out after drain pipes are installed at water flow area and after preparation of work yard.

Basic conditions of access road and routes are shown below

width: 4.0m (carriageway 3.0m, shoulder 0.5m)

vertical incline: 10% (for consideration of heavy equipment)

arrangement of access: at upper river stream side of A2 Abutment (less negative

influence to adjacent private houses and easy to access)

The structural body of substructure is removed by demolition by giant breaker and transportation.

②

② ①

①

③④⑤⑥⑦⑧

③ ④ ⑤ ⑥ ⑦ ⑧

⑨

⑨

N Sequence of removal

N Placement of c




18-111

The existing pile foundation should be basically pulled out and removed but may be cut off below

the formation level of river bank if removal is difficult.

Drain pipe of φ2.5m×3 is to be installed with estimating water level・discharge from the past

maximum water level in non-flood season at the site. The formation of work yard in the river is

assumed h=3.5m by securing the 1.0m of soil cover. The calculation results of water level・discharge is as shown in Table 18-46.

There is observation data of water level of river flow without tidal effect in only Votualevu

station (at point of 27.6km, during past 4 years) so that the water depth at Old Queens Road

Bridge is estimated h=0.822 (El.+2.322) applying the maximum water level at the station and

riverbed gradation. This water level is lower than the formation of work yard (El.+3.5m) and soil

cover of drain pipe is also secured. In this case the discharge is Q=33.7m3/s and drain pipe

ofφ2.5m×3nos. is required, The river channel here is engraved one so that if the water level・discharge is over than the estimated one in non-flood season inundation outside of bank will not

occur.




18-112

Table 18-46 Estimation of Water Level and Discharge in Non-flood Season in Diversion Work（Old Queens Road Bridge）

Distance from

Votualevu　Station

Difference

(height)

Water Level

(Maximum)

Average

RiverbedWater Depth Area Gradient Roughness Velocity Discharge Diameter

Install

Gradient

Water

Depth

Roughnes

sDischarge Number

Total

Discharge

Gauge

readingElevation

Adjust

ValueL2 ⊿h2 Elevation h3 A i n V Q1 φ i

(90%)

h4n q N Q2

(m) (EL.m) (m) (m) (m) (EL.m) (EL.m) (m) (m2) (m/s) (m3/s)

2011 2.325 9.979 1/ 4200 ：9.83k-16.75k －－－－－－－－ (m) (‰) (m) (m3/s) (m3/s)

2012 4.049 11.703 1/ 4200 ：16.75k-17.00k 2.322 1.5 0.822 17.124 0.000238095 0.060 1.968 33.7 ＜ 2.5 2.0 2.25 0.014 12.2 3 36.6

2013 3.262 10.916 1/ 1350 ：17.00k-25.00k －－－－－－－－

2014 0.987 8.641 1/ 630 ：25.00k-27.06k －－－－－－－－

Hume Pipe

Water Level (Maximum)*

I

7.654 10,310 9.38

year

Votualevu Observation Station (27.06k)

Gradient of Current Riverbed

Old Queends Road Bridge (16.75k)

※The discharge in diversion work is to be verified again in the detail design stage based on the up-to-date data and the timing of diversion as well as the possibility of

obtaining temporary work material (hume pipe with diameter ofφ2.5m).




18-113

4) Construction Plan of Substructures The plan of new substructure and foundation is shown in Table 18-47 and the general drawing for rebuilt bridge is shown in Figure 18-75.

Table 18-47 Plan of new Substructure and Foundation (Old Queens Road Bridge)

Item Type Remarks

Abutment Inverted T Refer to 18.6.3(3)4)a)

Pier Wall Refer to 18.6.3(3)4)b)

Foundation Cast in place Concrete Pile (Abutment), Spread Footing (Pier)

Refer to 18.6.3(3)5)





18-114

Figure 18-74 General Drawing of New Bridge (Old Queens Road Bridge -Road Bridge-)




18-115

Figure 18-75 General Drawing of New Bridge (Old Queens Road Bridge -Tramline Bridge-)




18-116

he type of foundation for Abutment should be Cast-in-Place Concrete Pile as selected in above Clause 18.6.3 (3)4, and be constructed (1) installation of outer steel casing (by Diesel Hammer method, Figure 18-76), (2) earth excavation within the casing, (3) installation of reinforcing bar cage, (4) concrete casting, in turn.

Figure 18-76 Example of Pile Construction (Pile driving by Diesel Hammer)


Reversed T type Abutments and Wall type Piers are planned, and these are constructed; (1) base excavation, (2) footing construction, (3) construction of structural body, (4) backfill, in turn after the construction of pile foundation.

Concrete is cast in place by Chute in case of close distance and by Crane in case of long distance or high place, and by Concrete Pump & Mixer in case of long distance & large quantity.

5) Election Plan of Superstructure Erection plan of new superstructure is summarized in Table 18-48.

Table 18-48 Superstructure Reconstruction Plan (Old Queens Road Bridge)



Span Division [email protected]

Width Road Bridge 10.000m (Sidewalk at one-side, W=1.5m)

Tramline Bridge 7.800m

Type of Bridge

Road Bridge PC 3span Continuous Post Tension I Girder

Tramline Bridge Steel 3span Continuous Through-Bridge

Erection Method

Road Bridge Girder Installation by Erection Beam (1st)

Tramline Bridge Girder Installation by Crane (2nd) Source: JICA Study Team

The method of girder installation by erection beam is employed for reconstruction of superstructure of Road Bridge because this bridge is river crossing bridge and also it is difficult to install the girder below the existing beams (Figure 18-77).




18-117

Figure 18-77 Example of Girder Installation by Erection Beam

(Left: Girder Fabrication at Work Yard on site, Right: Installation of Girder by Erection Beam)


Construction of Tramline Bridge is carried out on the bridge slab of Road Bridge after this bridge

is constructed in advance as mentioned in Clause 8.5.7(4)1).

Fabrication of primary girders for Tramline and Road Bridges is planned at the work yard which

can be secured behind the A1 Abutment

Superstructure of Road Bridge is erected in turn as; (1) site survey (confirmation of as-built

substructure), (2) installation of supports, (3) temporary rail laying, fabrication of erection beams,

(4) fabrication of primary girders, (5) installation of erection beams, (6) pull-out of primary

girders, (7) primary girder setting (repeat (4)~(7) as same nos. to girders), (8) move erection

beam to next span (repeat (4)~(8) as same nos. to span), (9) removal of erection beams, (10)

transverse beams, bridge slab.

The election girder method is that PC girder fabricated in the back yard of abutment is moved by

pre-installed election girder and shifted laterally and installed to the scheduled position by the

hanging girder device. Therefore the temporary works such as temporary support which block

river cross section is not required and the election work can be done above water level so that

construction can be done through a year.

Tramline Bridge is constructed in turn as; (1) site survey (confirmation of as-built substructure),

(2) installation of supports, (3) fabrication of primary girder, (4) installation by crane, (5) bolting,

(6) bridge slab.

When bridge slab is reconstructed, utilities should be restored.

Traffic of Road and Tramline Bridges passing by detour should be returned to new bridge after

construction of Road and Tramline Bridges are completed, and then the detour road (including

temporary bridge) is removed.

6) Process scheduling

The outline of construction schedule is as shown in Table 18-49. The substructure in the present river

channel is to be constructed in dry season. The superstructure is constructed by the election girder method

over the water surface and from behind of abutment so that the construction can be done through a year.




18-118

Table 18-49 Process Scheduling (Old Queens Road Bridge)

43 44 45 46 474th Year

482 3 4

37 38 39 40 41 42

RemovingExisting P1,2,7,8Pier

0.5

5 6Item M

1st Year 2nd Year 3rd Year1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 365 6 7 8 9 10 8 9 1011 12 1 2 3 4 411 12 9 10 11 121 2 3 85 6 1 2 3

3

PreparatoryWorks

1

745 6 7

AbutmentsWorks 2

Detour 1

TemporaryBridge

Coffering Works 0.5

Removing ExistingSuperstructure 6

RemovingCoffering Works

0.5

RemovingExisting P3-P6 Pier 0.5

11 12

Revetment WorksBoth Banks 1.5

ConstructionP1-P2 Pier 3

RemovingExisting Abutments 0.5

0.5

SuperstructureErection Works 16

17 8 9 10

Clear Works 0.5

RemovingTemporary Bridge 1.5

RemovingDetour

Dry Season Dry Season Dry Season

Tramline Operable Period Tramline Operable Period Tramline Operable Period

Dry Season


18.8.3 Whole Construction Work Schedule Whole Construction Work Schedule of this project which is combined river work and bridge work is as described in Table 18-50.




18-119

Table 18-50 Whole Construction Work Schedule

1 2 3 4 5 6 7 8 9 1 0 11 1 2 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 1 1 12

(day) (Month) 1 0 20 30 10 20 30 10 2 0 30 10 20 30 10 20 3 0 10 20 30 10 20 30 1 0 20 30 10 20 30 10 2 0 30 10 20 30 10 2 0 3 0 10 20 30 10 20 3 0 1 0 20 30 10 20 30 1 0 2 0 30 10 20 30 10 2 0 3 0 10 20 30 10 20 3 0 10 20 30 10 20 30 1 0 20 30 10 20 30 10 2 0 30 10 20 30 10 20 3 0 10 20 30 10 20 30 1 0 20 30 10 20 30 10 2 0 30 10 20 30 10 20 3 0 10 20 30 10 20 30 1 0 20 30 10 20 30 10 2 0 30 10 20 30 10 20 3 0 10 20 30 10 20 3 0 1 0 20 30 10 20 30 1 0 2 0 30 10 20 30

P1-1 Preparation 30 1.0Access Road 30 1.0

272 9.1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Earth Work Excavation 357 11.9 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1Embankment 378 12.6 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

180 6.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1Clearing 30 1.0 1 1 1

P1-2 Preparation 30 1.0 1 1 1Access Road 30 1.0 1 1 1

148 4.9 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1Earth Work Excavation 245 8.2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Embankment 245 8.2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1180 6.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1P1-3 Preparation 30 1.0 1 1 1

Access Road 30 1.0 1 1 138 1.3

Earth Work Excavation 186 6.2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Embankment 441 14.7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Structures 180 6.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

Preparation 30 1.0

Access Road 30 1.0

42 1.4 1 1 1 1

Earth Work Excavation 58 1.9 1 1 1 1 1 1

Embankment 148 4.9 1 1 1 1 1 1 1 1 1

270 9.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

Preparation 30 1.0

Access Road 30 1.0

Earth Work Excavation 6 0.2 1Embankment 63 2.1 1 1 1 1 1 1 1

90 3.0 1 1 1 1 1 1 1 1 1Clearing 30 1.0 1 1 1Preparation 30 1.0

Access Road 30 1.0

Earth Work Excavation 87 2.9 1 1 1 1 1 1 1 1 1

Embankment 91 3.0 1 1 1 1 1 1 1 1 1 1 1270 9.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Clearing 30 1.0 1 1 1

Preparation 30 1.0

Access Road 30 1.0Earth Work Excavation 63 2.1 1 1 1

Embankment 80 2.7 1 1 1 1 1

180 6.0

Clearing 30 1.0 1 1 130 1.0

30 1.0

90 3.0

420 14.0

420 14.0

300 10.0

Removal T emporary Bridges 60 2.0

Clearing 30 1.0

30 1.0

30 1.0

90 3.0

420 14.0

420 14.0

480 16.0

Removal T emporary Bridges 60 2.0

Clearing 30 1.0

Pack

age

Section Main Work ItemConstruction

Periond1 year 2 year 3year 4year


Structures


Riv

er W

ork

P1 R

iver

Wid

enin

g


Structures

Structures

P4-2

Structures

Structures

P3 R

ing

Dik

e P3

Structures

P2 R

etar

ding

Bas

in P2

Coffer dam

P4 S

urro

undi

ng D

ike

&Sh

ortc

ut

P4-1

PreparationAccess Road, Detour

T emporary Bridge Works

Superstructure Extention

Brid

ge W

ork

Reb

uild

ing

of B

ridge

s

Nadi T own Bridge

Removal Existing Bridges

Substructure

Superstructure Extention

Old Queens RoadBridge

Preparation

Access Road, Detour

T emporary Bridge Works

Removal Existing Bridges

Substructure

Dry Season Dry SeasonDry Season Dry Season

Drainage Suluice Gate Overflow Dike

Fabrication of Flood Wall Gate Installation of Flood Wall Gate

Flap Gate for drainage



Rainy Season Rainy Season RainyRainy Season Rainy Season

18.6 Rebuilding of Bridges 18.6.1 Basic Condition for Bridge ...

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