M.A.M.College of Engineering, Trichy

Department of Civil Engineering

CE1001 – Airport and Harbours

UNIT – 1 Question Bank

1. Define the term apron.

It is a paved area for parking of aircraft, loading & unloading of passengers and cargo.It is

usually located close to the terminal buildings or hangars.

2.What are the components of airport?

Landing area

Terminal area

Terminal building

Apron

Hangar

Vehicular parking and circulation area.

3.Define wind rose diagram.

The direction, duration and intensity of wind are graphically represented by a

diagram called wind rose diagram.

This is used for aligning a runway in a specified direction.

4.Define calm period.

The percentage of time in a year during which wind intensity is less than 6.4

Kmph is termed as calm period.

It is assumed that during calm period, intensity of wind is negligible.

5. What is the use of wind rose diagram?

1. Determination of orientation of runway.

2. Direction and duration.

3. Best orientation of runway.

4. Wind coverage.

6. Define taxiway.

Taxiways are the link between the runways and aprons. It provides access to

aircrafts from runways to aprons or service hangar and back.

Route of taxiways should be shortest as possible.

7. What is meant by separation distance?

From the safety point of view, two parallel taxiways should be separated by

adequate distance from each other, that adequate distance is known as separation distance.It

depends upon the type of aircraft.

8. Define the term hangar.

Hangar refers to the large sheds where repair, renovation, servicing and fuelling

of aircrafts are undertaken. Hangars are normally steel frame structures with galvanized iron

sheet roofs.

Ventilation is an essential requirement of hangars.

9. Define the term exit taxiway.

At busy airports, taxiways are provided at various points along the length of

runway, to clear off the runway by diverting aircrafts landing at runway by utilizing any taxiway

and to reach apron at service hangar.

10. Define the term holding apron.

The portion of paved area which is provided to the end of the runway in the case

of busy airport is known as holding apron.it is also defined as the final checking point of an

aircraft before takeoff.

PART - B

1.Explain the various components of an airport.

The various components of an airport are as follows;

(1) Landing area

(2) Terminal area

Apron

Terminal Building

Hangar

Vehicular parking & circulation

Landing area:

Airport landing area is the most critical of all operations. The landing area serves as a

focal point for activities of the airport. It includes terminal and operation building, vehicle

parking area, aircraft service hanger.

Apron:

It is the paved area for parking of an aircraft, loading and unloading of passengers and

cargo. It is usually located close to the terminal building or hangars. The size of the apron

depends upon, (i)size of loading area necessary for each type of aircraft , which is known as gate

position, (ii)Number of gate positions, (iii)Apron parking system. Size of the gate position

depends upon the following factors; (i)the size of the aircraft and its minimum turning radius,

(ii)the manner in which the aircraft enters and leaves the gate position under its own power,

(iii)Aircraft parking configuration- nose in , angle nose in, nose out, angle nose out, parallel.

Terminal Building:

The purpose of the airport building is to provide shelter and space for various surface

activities related to aircraft. They are planned for maximum efficiency, convenience and

economy. The extension of the building area in relation to the landing area depends upon the

present and future anticipated uses of airport.

Hangar:

Primary function of an hangar is to provide an enclose for servicing, overhauling and

doing repair of the aircraft. They are usually constructed of steel frame and covered with GI

sheets. They are also provided with mechanism shop and stores for spare parts. The size of the

hangar depends upon the size of the aircraft and its turning radius. Adequate lighting inside the

hangar is of prime importance.

2. Design standards of taxiway:

Length of taxiway

Longitudinal gradient

Rate of change of longitudinal gradient

Transverse Gradient

Width of taxiway

Width of safety area

Turning radius

Sight distance

Length of taxiway:

The length of the taxiway should be sufficient to connect the runway entry end or exit

end. No special recommendations are given by ICAO. It should be as short as possible.

Longitudinal gradient:

Steeper gradient will consume more fuel and aircraft will require greater ground speed to

attain elevation. ICAO recommends 1.5% longitudinal gradient for A and B class airport and 3%

for C, D and E class airport.

Rate of change of longitudinal gradient:

The available sight distance on runway is affected by the rate of change of longitudinal

gradient. The maximum rate of change of slope for 30m length of vertical curve recommended

by ICAO is 1% for A,B and C class airport and 1.2% for D and E class airport.

Sight distance:

Smaller value of sight distance is sufficient in taxiway as the aircraft move on taxiway

with lower speed. ICAO recommends for A and B class airport, the surface of the taxiway should

be seen for a distance of 195m from a point of 2.1m above the taxiway and for C, D and E class

airport, a taxiway distance of 300m should be visible from a height of 3m above the taxiway.

Transverse gradient:

Transverse gradient are provided on the taxiway for quick disposal of rain water or

surface water. ICAO recommends a transverse gradient of 1.5% for A,B and C class airport and

2% for D and E class airport.

Turning radius:

A horizontal curvature is provided at the basis wherever there is change in the direction

of taxiway. It should be designed in such a way that the aircraft should negotiate the horizontal

curvature without reducing its speed. Usually circular curvature of larger radius is provided.

Radius of curvature, R = 𝑉2

125𝑓

R= radius in metres

V= speed in kmph

f= coefficient of friction

Width of safety area:

The safety area usually have partially paved shoulder on either side of taxiway which is

graded and drained. It may extend up to the point where it intersects a parallel runway, taxiway

or apron.

Width of taxiway:

The width of the taxiway will be less than the width of the runway. The reasons are;

(i)The aircraft are not airborne on the taxiway

(ii)speed of aircraft on taxiway is very less when compared to the runway.

3.Problems in runway length corrections:

Problem 1: The length of a runway under standard condition is 1620m. The airport site has an

elevation of 270m above MSL. Its reference temperature is 32.94°. If the runway is to be

constructed with an effective gradient of 0.2%, determine the corrected runway length.

Solution:

Step 1: Correction of elevation:

Correction of elevation = 7

100 𝑋 1620 𝑋

270

300 = 102m

Corrected length = 1620 + 102 = 1722m

Step 2: Determination of standard atmospheric temperature at the given elevation:

Standard atmospheric temperature = 15° - 0.0065 X elevation of site above MSL

= 15° - 0.0065 X 270 = 13.18° C

Step 3: Correction for temperature:

Rise of temperature = 32.9° - 13.18° = 19.72°

Correction for temperature = 1722

100 𝑋 19.72 = 340𝑚

Corrected length = 1722 + 340 = 2062m

Step 4: Check for the total correction of elevation and temperature:

Check = 2060−1620

1620 𝑋 100 = 27.3% < 35%

It is less than the max value of 35% given by ICAO. Hence it is ok.

Step 5: Correction for gradient:

Correction for gradient = 20

100 𝑋 2060 𝑋 0.2 = 82.48𝑚

Therefore, corrected length = 2062 + 82.48 = 2144.48m (after all corrections)

Result: the final runway length obtained as a rounded value after all corrections = 2150m.

Problem2: The length of a runway under standard condition is 2100m. The airport is to be

provided at an elevation of 410m above MSL. The airport reference temperature is 32°C. The

construction plan provides the following data.

End to end of runway (m) Grade (%)

0 – 300 +1.0%

300 – 900 - 0.5%

900 – 1500 +0.5%

1500 – 1800 + 1.0%

1800 – 2100 - 0.5%

2100 – 2700 - 0.4%

2700 – 3000 -0.10%

Determine the length of the runway. Apply the correction for elevation and temperature as per

ICAO and the correction for gradient as per FAA.

Solution:

Step 1: Correction for elevation:

Ce = 7

100 𝑋 2100 𝑋

410

300 200𝑚

Corrected length = 2100 + 200 = 2300m

Step 2: Correction for temperature:

Standard atmospheric temperature = 15°C – 0.0065 X elevation above MSL

= 15° - 0.0065 X 410 = 12.34°

Rise of temperature = 32- 12.34 = 19.66°

Ct = 2300

100 𝑋 19.66 = 452𝑚

Corrected length = 2300 + 452 = 2752m

Step 3: Check for the total correction of elevation and temperature:

Check = 2752−2100

2100 X 100 = 31.05 % < 35%

It is less than the max value of 35% given by ICAO. Hence it is ok.

Step 4: Check for gradient:

Chainage (100m): 0 3 9 15 18 21 27 30

Elevation (m): 100 103 100 103 106 104.5 102.1 101.8

Effective gradient = 20

100 𝑋 2755 𝑋 0.218 = 120.5𝑚

Corrected length = 2755 + 120.5 = 2875.5m

4.GEOMETRIC DESIGN OF RUNWAY:

1) RUNWAY LENGTH:

The basic runway length given by ICAO is as follows.

Airport type Basic runway length (m) Width of the

runway pavement

Maximum

longitudinal

gradient (%) Max Min

A - 2100 45 1.5

B 2099 1500 45 1.5

C 1499 900 30 1.5

D 899 750 22.5 2.0

E 749 600 18 2.0

The above runway length will undergo corrections for elevation, temperature, combined

corrections and gradient and the final length arrived will be the actual length and will be

implemented in the field.

2) RUNWAY WIDTH:

As per ICAO recommendation the width of runway ranges from 18m to 45m.

3) TRANSVERSE GRADIENT:

Transverse gradient is provided in the runway for the quick disposal of rain

water and to avoid ponding of water at any point of runway.

Airport type Width of the

runway (m)

A 45

B 45

C 30

D 22.5

E 18

As per ICAO recommendation a value of 1.5% is provided for class A, class B

and C airport and 2% will be provided for D and E class airport. Under any

circumstances this value should not be less than 0.5%.The shoulder on either side of

runway will be provided with steep gradient.

4) LONGITUDINAL and EFFECTIVE GRADIENT:

The longitudinal gradient of runway increase the necessary runway

length.ICAO gives the following recommendation for maximum longitudinal gradient

and the maximum effective gradient.

Longitudinal gradient:

For A,B and C class airport = 1.5%

For D and E class airport = 2.0%

Effective gradient:

For A,B and C class airport = 1%

For D and E class airport = 2%

5) WIDTH OF SAFETY AREA:

The runway safety area is an area which is cleared,drained and graded.It

includes the structural pavement,shoulders on either side of runway and the additional

width.The shoulders are generally unpaved as they are used only in case of emergency.

As per ICAO the minimum width of safety area,

Total safety area=Length of runway+120m

6) SIGHT DISTANCE:

There is generally no sight distance restriction as the longitudinal gradient for

the runway is smooth.But there are chances for collision of aircraft at the point where 2

runways or a runway and a taxiway intersect each other.

For A,B and C class airport any 2 points 3m above the surface of runway

should be mutually visible from a distance=1/2 the runway length.

5.CORRECTION EMPLOYED IN ARRIVING RUNWAY LENGTH:

1) CORRECTION FOR ELEVATION:

As the elevation increases the air density increases,due to this the aircraft

requires greater ground speed to do take off by utilizing greater length of runway.

As per ICAO recommendation, the runway length should be raised by 7% for

every 300m rise above mean sea level (MSL).

2) CORRECTION FOR TEMPERATURE:

The increase in temperature as the same effect as that of elevation.Airport

reference temperature is defined as the monthly mean of average daily temperature(Ta)

for hottest month of the year plus one third difference of this temperature (Ta) and the

monthly mean of the maximum daily temperature for the same month.

Airport reference temperature=Ta+Tm-Ta

3

3) COMBINED CORRECTION FOR ELEVATION AND TEMPERATURE:

ICAO recommends if the total correction for elevation and temperature exceed

35% then specific studies should be carried out at the site using models.

4) CORRECTION FOR GRADIENT:

Steeper gradient result in consumption of more fuel and also the aircraft will

be utilizing longer length of runway to attain sufficient ground speed before takeoff.

ICAO does not indicated any specification whereas FAA recommends the basic runway

length should be further increased by 20% after correction for elevation and temperature.

Effective gradient is defined as the maximum difference in elevation between

the highest points and lowest point of the runway is divided by the total length of

runway.It is expressed in %.

6.WIND ROSE DIAGRAM:

TYPE I: Showing direction and duration of wind

This type of wind rose is illustrated in diagram.The radial lines indicate the wind direction and

each circle represents the duration of wind.From the table it is observed that the total percentage

of time in a year during which the wind blows from north direction.This value is plotted along

the north direction is similarly other values are also plotted along their respective direction.All

plotted points are then jointed by straight lines.The best direction of runway is usually along the

direction of the longest line on wind rose diagram.The best orientation of runway is thus along

NS direction.If deviation of wind direction upto(22.5+11.25) from the direction of landing and

takeoff is permissible,the percentage of time in a year during which the runway can safely be

used for landing and takeoff will be obtained by summing the percentage of time along

NNW,N,NNE,SSE,S and SSW directions.This comes to 570 percent calm period i.e,the

percentage of time during which wind intensity is less than 6.4kmph is also added to the above

period.

TYPE II: Showing direction,duration and intensity of wind:

This type of wind rose is illustrated in diagram.The wind data as in the previous type is used for

this case.Each circle represents the wind intensity to some scale.The values entered in each

segment represent the percentage of time in a year during which the wind,having particular

intensity blows from the respective direction.The procedure for determining the orientation of

runway is described below,

1) Draw three equi-spaced parallel line on a transport paper strip in such a way that the

distance between the two nearby parallel lines is equal to the permissible cross wind

component.This distance is measured with which the wind rose diagram is drawn.The

permissible cross wind component is 25Kmph.

2) Place the transparent paper strip over the wind rose diagram in such a way that the central

line passes through the centre of the diagram.

3) With the centre of the wind rose,rotate the tracing paper and place it in such a position

that the sum of all the values indicating the duration of wind,within the two outer parallel

lines is the maximum.The runway should be thus oriented along the direction indicated

by the centre line.The wind coverage can be calculated by summing up all the percentage

shown in segment.The percentage value is assumed to be equally distributed over the

entire area of the segment.when the outer parallel lines of the transparent strip crosses a

segment,a fractional part of the percentage appearing in that segment within the outside

lines is also counted in the summation.Fractional areas are determined by judgement to

the nearest decimal place.

4) Read the bearing of the runway on the outer scale of the wind rose,where the central line

on the transparent paper crosses the angular scale.The best orientation of runway is along

the direction whose whole circle bearing is zero degree ie. Along NS direction.

5) If the coverage provided by a single runway is not sufficient two or more number of

runways are planned in such a manner that the total coverage provided by them is as

required.