CE 141 Transportation Engineering ISection: WFU

GROUP EXERCISE NO.2:SPOT SPEED SURVEY

Submitted by:

Licerio, Arthel RaeLeobrera, Karen

Lim, ErnestLagason, Patria

De Leon, JodieDy, Edgene

Eliseo, Benjie

March 5, 2014I. Spot Speed Survey Report

II. Purpose of the Activity Perform a spot speed survey using the trap length

method on the west bound vehicles of Magsaysay StcorAgoncillo St.

Prepare the frequency histogram for the observedspot speed using the trap length method.

Use the speed gun to determine instantaneousspeeds of the vehicles.

Compare and analyze the results between the traplength method and the speed gun.

III.Description of the Survey Areaa. Location

The area of study is along Magsaysay AvecorAgoncillo St.

b. Date and TimeThe survey was conducted on January 22, 2013(10:41am – 11:41am)

c. WeatherThe weather on the day of the survey wassunny.

d. Traffic ControlThere were no traffic lights within thesurvey area. Only traffic signs were seensuch as guide signs and regulatory signs.

e. Road Condition

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The road was in good condition. Also, smallamount of vehicles passed through the survey areaduring the time of survey.

f. Map

IV. Results and Data

Table 1: Speed of Vehicles based on Trap Length Methodand Speed Gun

ClockTime

(hh:mm)

VehicleType

TimeTaken(mm:ss)

Speed(kph) NOTE

%Error(T-A)/T

11:17 Car 3.4231.5789

5REU 702, 28kph

11.33333

Medium Truck 3.42

31.57895

Car 1.8558.3783

8XMC 870, 49kph

16.06481

11:18 Car 4.3624.7706

4

Car 2.4344.4444

4TIT 237, 36kph 19

Car 3.17 34.0694UOI 171, 31kph

9.009259

2

30 meters

Car 2.44 44.2623TBO 977, 37kph

16.40741

Motor 4.0226.8656

7 22kph18.111

11Car: Pick-up 4.11

26.27737

Car: Taxi 4.0126.9326

7

Motor 4.0526.6666

7

11:19 Car: Taxi 2.1550.2325

6TYM 203, 44kph

12.40741

Car 3.4531.3043

5ZFC 953, 32kph

2.222222

Medium Truck 3.88

27.83505

Car 3.5430.5084

7

11:20 Car: L300 3.1234.6153

8SKT 841, 34kph

1.777778

Car 3.2133.6448

6TSO 286, 32kph

4.888889

Car 2.70 40

11:21 Car 2.5841.8604

7

Car 3.3232.5301

2SJV 561, 32kph

1.62963

Motor 3.3732.0474

8

11:22 Car 3.8328.1984

3UNO 975, 25kph

11.34259

Car: Taxi 3.17 34.0694UVL 343, 33kph

3.138889

Motor 1.7462.0689

7

Car 3.2133.6448

6

The table above showed the speed of the vehicles thatpassed through the survey area based on a) trap length methodand b) speed gun. Here, one can see that the maximum percent

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deviation between the two methods was about 19%. This may bebecause when the speed gun was used, the vehicles were about40m away from it and when they passed through the indicatedtrap length area, they may have slowed down a bit since anintersection can be found just a few meters away from the traplength.

Table 2: Data for Frequency Histogram

Bin Frequency5 0

10 015 020 325 730 2435 4640 5745 5250 2155 1160 565 670 0

More 1

Table 2 shows the data that is used to produce thefrequency histogram. The data in the table is from the datagathered during the survey (speed of the vehicles). The “More”bin is to denote the outlier which is excessively distant fromthe other observed value. It can be seen from the table that40 has the highest frequency, followed by 45 and then by 35.This means that 24.46% (57 out of 233) of the cars thattravels along the Magsaysay road is driving at the speed of 40kph.

Figure 1: Spot Speed Frequency Diagram

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10 15 20 25 30 35 40 45 50 55 60 65 70 More0102030405060

Frequency Histogram

Speed (kph)

Freq

uenc

y

Based on the frequency histogram, one can see that duringthe entire duration of the survey, 155 cars (out of 233)travelled at a speed of 35-45kph which was larger than thespeed limit of 30kph. And in total, the amount of cars largerthan 30 kph is 199 and the amount of cars that complied withthe speed limit is only 34. Only 15% of cars that pass throughMagsaysay road comply with the speed limit between 10:00am and11:30am. It can also be observed in Figure 1 that the data isnormally distributed since it shows a bell shaped curve.

V. Method of Data Collection

A. Materials Used: (1) Analog Distance Measuring Wheel (2) Timers (1) Speed Gun (only used for 10 minutes) Markers (Masking Tape)

B. Procedure:Trap Length Method:

The Trap Length method was used in this

activity to determine spot speed. The length of road

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for the survey was set to 30m which was measured using

the analog distance measuring wheel. Start and end

points were designated using the markers. For the

survey, the group chose to use two timers, two flagmen

and two recorders. This set up allows the group to

record the time spent of two simultaneous cars in the

trap length which was impossible for the original set

up. The additional data makes the survey more credible.

The trap length method was performed as follows:

Every time a car passes the start marker, the

flagman for the first timer raises his hand.

The first timerthen starts the digital timer

and ends it when the vehicle passed the end

marker. The timer then takes note of the time

and notifies the recorder of the value. If

there are two succeeding cars passing by, the

second flagman also raises his hand, and then,

the second timer takes note of the time. The

second timer then notifies the second recorder.

This went on for one hour with the two set of

timers alternate between the vehicles.

The spot speed for each vehicle was computed

using the formula:

SpotSpeed= TraplengthTime∈spent∈trap

Speed Gun:

There was also a short period of time (10

minutes) in which the speed gun was used. It was done

by pointing the gun at the different vehicles to take6

their instantaneous speeds. During the ten minutes

allotted, the speed gun was utilized along with the

trap length method. The plate numbers of cars that were

observed using both the trap length method and the

speed gun were also recorded along with the cars'

speed.

VI. Analysis and Discussions

The survey was conducted using two methods; Trap LengthMethod and Speed Gun. The trap length method determines thespot speed using Equation (1). The speed determined by thetrap length is called the average speed. The average speed isthe estimated pace of an object moving from one point toanother at a certain period of time. Meanwhile, the speed gundetermines the instantaneous speed. This speed is the speed ofa moving object at that specific point in place and in time.This means that vehicles can have various instantaneous speedswhile passing through the trap length. The average speed isthe mean of all the instantaneous speeds of the vehiclepassing through the trap length. This was the reason that thetwo methods produced varying percentage of errors (rangingfrom 1% to 19% error from Table 1). Figure 2 (below) shows thefrequency histogram of the two methods and how much thedifference varies between the two methods.

Figure 2: Frequency Histogram of the Two Methods

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1 2 3 4 5 6 7 8 9 10111213141516170

10

20

30

40

50

60

70

Frequency Histogram of the Two Methods

Trap Length MethodSpeed Gun

Vehicles

Speed (kph)

Therefore, the trap length is more effective atestimating the speed of vehicles at certain roads since it isthe average of all the instantaneous speeds of the vehicles.The speed gun is more useful in determining the exact speed ofvehicles. This is useful in checking whether vehicles complywith established speed limit of a road. For the survey, thespeed limit of the road used was 30 kph.

Table 3: Average of speeds per vehicle type

Vehicle No.

AverageSpeed(kph)

Car187

38.9647582

Jeepney 539.75819

77

Motorcycle 3539.79600

21

8

Bicycle 325.63515

75Medium Truck 3

30.9501771

TOTAL233  

Table 3 shows the number of vehicles per vehicle typethat passed through the trap length along with theircorresponding mean speed. It can be observed that themotorcycles have the highest average speed with 39.8 kph andthat bicycles demonstrated the lowest speeds with an averageof 25.6 kph. From the table, It can be inferred that cars,jeepneys, motorcycles and medium-sized trucks generally havespeeds greater than 30kph (speed limit at the campus).

Table 4: Number of Vehicles that are Overspeeding and Non-overspeeding

 

No. Of Vehicles

%

No. of overspeedingvehicles 199

85.4077253

No. of vehicles thatdidn't overspeed 34

14.5922747

Figure 3: Number of Vehicles that are Overspeeding and Non-overspeeding

85%

15%No. of overspeeding vehicles

No. of vehicles that didn't overspeed

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Table 4 and Figure 3 show the number of vehicles andpercentage that went overspeeding and those who complied tothe speed limit. 85% (199 vehicles) of the motorists areoverspeeding inside the campus and only 15% (34 vehicles)complies with the speed limit (as observed on the surveyarea).

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