INTRODUCTION

The traditional methods of conducting laboratory activities

will not be able to provide the avenue for students to enhance

independent learning activities and inculcate creativity and

innovation. Level 0 is fully prescriptive where problem, ways &

means and answers are provided to the students. However it is

still necessary especially to first and second year students.

In this laboratory activity, students are required to

conduct a spot speed study by recording the speeds of sample

of vehicles at a specified location in order to estimate the

distribution of speeds of vehicles. Students are provided with

the methodology and guidelines for results and analysis to be

presented in their report.

OBJECTIVES

1. To establish the speed distribution of a traffic at a

specific site or called as basic speed data.

2. To determine vehicle speed percentiles via speed trend

analysis, which are useful in speed related decision

making.

THEORETICAL BACKGROUND

The distribution of speeds of vehicles in a traffic at a

certain place on a road can be found through spot speed

studies. The speed of a vehicle is defined as the rate of

movement of the vehicle which be regarded in kilometers per

hour (km/h). A spot speed study is carried out by recording

the speeds of a sample of vehicles at a specified location.

However, speed characteristics identified by such a study will

be valid only for the traffic and environmental conditions

that exist at the time of the study. (Garber & Hoel, 2009)

Speed characteristics determined from a spot speed study

may be used to:

• Establish parameters for traffic operation and control, such

as speed zones, speed limits (85th-percentile speed is

commonly used as the speed limit on a road), and passing

restrictions.

• Evaluate the effectiveness of traffic control devices, such

as variable message signs at work zones.

• Monitor the effect of speed enforcement programs, such as

the use of drone radar and the use of differential speed

limits for passenger cars and trucks.

• Evaluate and or determine the adequacy of highway geometric

characteristics, such as radii of horizontal curves and

lengths of vertical curves.

• Evaluate the effect of speed on highway safety through the

analysis of crash data for different speed characteristics.

• Determine speed trends and determine whether complaints

about speeding are valid.

APPARATUS AND MATERIALS

1. Radar speed meter (Radar gun)

2. Safety vests

3. Measuring wheel

4. Clipboard and field data form

5. Stopwatch

PROCEDURES

1. The necessary preparations was performed such as

sufficient pen or pencils, radar meter spot speed study

data forms and clipboards, radar speed meters are in good

condition, the instructions were read for the used radar

gun, obtain power battery, safety vast and others.

2. The study location was decided. The selected site should

be a straight and level road sections that represents

different traffic conditions.

3. Enumerators should arrive 30 minutes earlier at side in

order to familiarize by visual survey with it prior to

select strategic location. The equipment was distributed,

the general information of the speed spot data recording

forms were filled that comprise the observer’s name,

time, date, name of site, posted speed limit and weather

condition and begin at the planned time.

4. The layout of the study area was sketch with the

description of chosen reference points, position of

observation, number of lanes and road class.

5. The enumerators, the radar unit and the station for speed

data collection should be inconspicuous where possible so

that vehicular speeds are significantly not effected by

the data collection activities.

6. The samples were randomly selected, for example the

observer recorded a speed reading for every third vehicle

or every fifth vehicle.

7. The radar meter should be made as direct a line with

oncoming traffic as possible, meaning to make it as close

to the roadway as possible (an exception when the

vehicles selected and radar unit tends to affect vehicles

speeds considerably.)

8. A slash was recorded on the speed data sheet

corresponding to the speed observed for each selected

vehicle under the appropriate vehicle-type

classifications.

9. The vehicle speeds were observed for the 100 samples.

RESULT

TABLE 1: THE FREQUENCY ACCORDING TO VEHICLE CLASSIFICATION

Speed

range

(km/h)

VEHICLE TYPES

Motorcycl

es

Cars Buses Lorries Vans

16 - 20 - 1 - - -

21 - 25 - 1 - - -

26 - 30 2 - - 1 2

31 - 35 4 14 2 4 -

36 - 40 9 14 - 2 -

41 - 45 8 19 - - -

46 - 50 9 5 - - -

51 - 55 1 1 - - -

56 - 60 1 - - - -

TOTAL 34 55 2 7 2

SPEED

RANGE

(km/h)

MID

SPEED

, U

(km/h

)

FREQUENCY,

F

F*U

FREQUENCY

PERCENTAGE

(%)

CUMULATIVE

FREQUENCY

(%)

F(U-

Ub)2

16-20 18 1 18 1 1 449.4421-25 23 1 23 1 2 262.4426-30 28 5 140 5 7 627.231-35 33 24 792 24 31 922.5636-40 38 25 950 25 56 36

41-45 43 27116

127 83 389.88

46-50 48 14 672 14 97 1084.1651-55 53 2 106 2 99 380.8856-60 58 1 58 1 100 353.44

TOTAL   100392

0    4506

16-20 21-25 26-30 31-35 36-40 41-45 46-50 51-55 55-600

5

10

15

20

25

30

1 1

5

24 2527

14

2 1

FREQUENCY HISTOGRAM

VEHICLE SPEED RANGE (km/h)

FREQUENCY OF VEHICLE

FIGURE 1: FREQUENCY HISTOGRAM

CALCULATION

1. Arithmetic Mean Speed, Ub = ∑FUF

= 3920100

= 39.2

2. Median Speed

From graph figure 3, P50 = 37 km/h

3. Modal Speed

From the Histogram in figure 1, the Modal Speed is at

range 41 – 45 km/h with the number of frequency of 27

vehicle.

4. Standard Deviation

S = √∑f (U−Ub)2

N−1

S = √ 4506100−1

= ± 6.75

5. Standard Error

D = SN

= 6.75100

= 0.675

Adequacy of data for 95 % confident significant level

95% mean + 1.96 D

= 32.9 + 1.96 (0.675)

= 31.59 to 34.22

6. From Graph;

P15 = 30.5 km/h

P85 = 43.5 km/h

P98 = 49.5 km/h

DISCUSSION

Our study was done along the road from Pejabat Bendahari

towards Dataran Cendekia. The study involved 100 number of

data which includes cars, buses, vans, lorry and motorcycles.

The road was chosen because it is often used by the road users

in UiTM. Apart from that, the road is straight and no

intersection at which the observation can be disturbed.

We have done the observation by shooting the vehicles

using the radar gun at 30o angle. This is to ensure the result

to be more accurate. It was done from 2.45 pm to 3.20 pm.

Based on Garber and Hoel, speed characteristics can be

found from the significant values during the observation.

These values are average speed, median speed, modal speed, the

ith-percentile spot speed, pace and standard deviation of

speed. (Garber & Hoel, 2009)

Based on the calculation done, it can be found that the

arithmetic mean speed is 39.2 km/h. Meanwhile, the median

speed is 37 km/h which is obtained from the cumulative

frequency distribution curve. The median speed is also known

as the 50th-percentile speed. At the 15th, 85th and 98th-perentile

speeds are 30.5 km/h, 43.5 km/h and 49.5 km/h respectively.

Next, the modal speed is 43 km/h according to the

frequency histogram. The standard deviation has been

calculated using its respective formula and found to be ±6.75km/h.

The term 'Pace' refers to the range of speed which shows

the biggest number of observations. (Garber & Hoel, 2009) In

our observation, a set of speed data between 16 and 60 km/h.

Thus, we decided to use an interval of 5 km/h. The pace is 41

km/h to 45 km/h since it shows the highest number of

observations.

The standard error that is allowed in the experiment is ±0.675 km/h. The adequacy of data for 95 % confident

significant level was checked and found to be between 31.59 to

34.22 km/h.

CONCLUSION

It can be concluded that, the speed distributions of the

vehicles along our study location have been observed through

spot speed study. For this experiment, the data were collected

by using radar gun method. It was found that the highest speed

tabulated was in the range 41 km/h to 45 km/h. Moreover, it

can also be observed that the road has highest number of car

users which are 55 out 100 vehicles.

According to a study done by University of South

Florida’s Center for Urban Transportation Research (CUTR), a

speed limit of 40 km/h was recommended for its campus area.

(USF Speed Limit Study, 2013)

If our campus were to use this recommended limit, it can

be seen that the mean speed found in our study is not

suitable. By implementing new speed limit, it can ensure more

safety especially for the pedestrians, bicycle users as well

as motorcycle users.

RECOMMENDATION

In addition, there are several factors that need to be

well taken to ensure the accuracy of the data such as the

location for the study, time of day, period of the study and

the minimum sample size necessary for the limit of acceptable

error. (Garber & Hoel, 2009)

The radar gun should be used to shoot the vehicle at 30o

angle and should not be obvious to the sight of the vehicles'

user.

Therefore, it can be suggested that our university should

implement a safe speed limit to increase safety and reduce the

number of accidents in the campus area.

REFERENCES

Garber, N. J., & Hoel, L. A. (2009). Traffic & Highway Engineering Fourth Edition. Toronto: Cengage Learning.

USF Speed Limit Study. (2013, 10 16). Retrieved from Center for Urban Transportation Research (CUTR):

http://www.cutr.usf.edu/2013/10/usf-speed-limit-study/

APPENDIX

Picture 1, 2 & 3: These are some of the apparatus and

materials used for the study.

Picture 4: The picture above shows our study location

which is in front of Pejabat Bendahari.

Picture 5: One of our group member used the measuring wheel to

measure the width of the road.

Picture 6: The radar gun was used to capture the vehicles'

speed and the other members will record the reading as well as

type of cars.

Picture 7 & 8: The pictures show some of the vehicles that

were included in our sample data.