HIGHWAY LABORATORY

CIVIL ENGINEERING DEPARTMENT

SULTAN AZLAN SHAH POLYTECHNIC

EXPERIMENT : 2

TITTLE : SPEED SPOT STUDIES

OBJEKTIF : TO ANALYSE THE SPEED AND THE AMOUNT OF VEHICLES ON A

DETERMINED ROAD.

INTRODUCTION :

To Analyse the Speed and the amount of vehicles on a determined road.

Spot Speed is the average speed of vehicles passing a point, or the time mean speed.

Spot speed studies are conducted to estimate the distribution of speeds of vehicles in

a stream of traffic at a particular location on a highway. Carried out by recording the

speeds of a sample of vehicles at a specified location. Spot speed studies are used to

determine the speed distribution of a traffic stream at a specific location. The data

gathered in spot speed studies are used to determine vehicle speed percentiles,

which are useful in making many speed-related decisions.

THEORY :

Figure 1 : Flow Chart

Spot speed data have a number of safety applications, including the following

(Robertson 1994):

1. Determining existing traffic operations and evaluation of traffic control devices :

a. Evaluating and determining proper speed limits

b. Determining the 50th and 85th speed percentiles

c. Evaluating and determining proper advisory speeds

d. Establishing the limits of no-passing zones

e. Determining the proper placements of traffic control signs and markings

f. Setting appropriate traffic signal timing

2. Establishing roadway design elements:

a. Evaluating and determining proper intersection sight distance

b. Evaluating and determining proper passing sight distance (for more

information refer to Chapter 3 in the AASHTO Green Book)

c. Evaluating and determining proper stopping sight distance

3. Assessing roadway safety questions:

a. Evaluating and verifying speeding problems

b. Assessing speed as a contributor to vehicle crashes

c. Investigating input from the public or other officials

4. Monitoring traffic speed trends by systematic ongoing speed studies.

5. Measuring effectiveness of traffic control devices or traffic programs, including

signs and markings, traffic operational changes, and speed enforcement programs.

For a spot speed study at a selected location, a sample size of at least 50 and

preferably 100 vehicles is usually obtained (Ewing 1999). Traffic counts during a

Monday morning or a Friday peak period may show exceptionally high volumes and

are not normally used in the analysis; therefore, counts are usually conducted on a

Tuesday, Wednesday, and Thursday. Spot speed data are gathered using one of three

methods: (1) stopwatch method, (2) radar meter method, or (3) pneumatic road tube

method. These methods are described in this chapter in order from least expensive to

most expensive. The stopwatch method is the least expensive and least accurate of

the methods.

Application of Spot Speeds :-

1. Speed Limit Studies

2. Establishing Speed Trends

3. Specific Design Applications

4. Specific Control Applications

5. Investigation of High Accident Locations

Figure 2 : Stop Watch Speed Study

Figure 3 : Example Radar Meter Spot Layout

APPARATUS

1. Radar Gun

2. Analog Counter / Watch

3. Form HW1, Form HW2, and Form HW3

2. Safety Jacket

3. Form HW1, Form HW2, and Form HW3

PROCEDURES

1. Identify the location

2. Get vehicles speeds on the road using the radar gun and record

sure you are hidden from the driver).

3. Make sure the “LAMP TEST”

and “4 LED” indicators light up

4. Warning! Testing should be

equipment.

5. Count and classify the vehicles

- Class 1 (Motocycle)

- Class 2 (Cars)

6. Record the numbers of vehicle and vehicle speeds according to their respective

class.

7. Using the data, draw the:

a) Line graph – Number of vehicles vers

b) Histogram graph –

c) Line graph – Number of vehicles versus speed

d) Line graph – cumulative sum of vehicle versus speed.

2. Get vehicles speeds on the road using the radar gun and record the data (make

sure you are hidden from the driver).

“LAMP TEST” on the radar gunner pressed, the display

light up before starting the test.

should be stopped when “LO VOLT” lights to prevent

. Count and classify the vehicles according to class using the analog counter.

- Class 3 (Van and Small Lorries)

- Class 4 (Big Lorries & Buses)

. Record the numbers of vehicle and vehicle speeds according to their respective

. Using the data, draw the:

Number of vehicles versus time according to vehicle class

Number of vehicles versus time.

Number of vehicles versus speed

cumulative sum of vehicle versus speed.

the data (make

the display shows "888"

prevent damage to

according to class using the analog counter.

Class 3 (Van and Small Lorries)

Class 4 (Big Lorries & Buses)

. Record the numbers of vehicle and vehicle speeds according to their respective

us time according to vehicle class

8. From the result, suggest a reasonable average speed (example Speed Limit and

Speed Zones) in order to improve the traffic flow and for the safety of the road users.

DISCUSSION

Analysts : Group B Area : Behrang State : Perak

Starting : 10.30am Date : 4th

January 2011 Day : Monday

Station : Polytechnic Bus Stand Direction Of : Slim River Toward : Behrang Stesen

Wather : 29 0

(Warm)

Direction:

1. Sketch the graph (%) of cumulative versus vehicle speed

2. From the graph, get to 5%, to 85% and 50% to.

� % 15 = Minimum Rate

� % 85 = Rate Design

� % 50 = Median Rate

3. Get the result,

������� ��� (�) , ∑��∑� =

����.��� = 64.7

������� �������� (�), =�∑���∑� − �∑��

∑� 2

GROUP RATE AVERAGE

RATE IN

GROUP (x)

NUMBER

VEHICLE IN

GROUP (f)

%

VEHICLE IN

GROUP

%

CUMULATIVE

VEHICLES

(f) x (x) f (x2)

25 – 38 31.33 3 4 4 93.99 2944.71

39 – 52 40.47 18 20 24 728.46 29480.77

53 – 66 57.27 24 27 51 1376.88 78991.60

67 – 80 72.23 30 33 84 2166.90 156515.20

81 – 94 86.73 11 12 96 954.03 82743.00

95 – 108 100.00 2 3 99 200.00 20000.00

109 – 122 117.50 2 3 102 235.00 27612.50

123 – 136 130.00 1 1 103 130.00 16900.00

∑ = 91.00 ∑ = 5885.30

Solution:

1. #�$�%$��� = 31.33

2. ���� x 100 = 3.34

3. 4 + 20 + 27 + 33 + 12 + 3 + 3 +1 = 103

4. ������� ��� (�) , ∑��∑� =

����.��� = 64.7

4. ������� �������� (�), =�∑���∑� − �∑��

∑� 2

= �%����(.��� – *64.21,#

= √4563 − 4186

= √377 = 19.4

CONCLUSION

Overall, the Spot Speed Training Session was a success. With an original goal of

1hour study speed spot, the interest of Class 1 and Class 2 with average speed 90

km/h. Feedback provided both during the discussion session and in subsequent

correspondence indicates that the session was well-received and that future

implementation of a full schedule of Spot Speed Training Sessions at locations

throughout Behrang, Perak

Consider the following typical situation. An accident analysis at a critical

location indicates that excessive speeds are a principal causative factor in the

frequent accidents. As a result, limit 70 - 80km/h it is reasonable speed limit signs at

the area and a lower limit is encourage. Speed studies at the location show some

reduction in average speed at noon.

REFERENCE

Currin, T. R. 2001. Spot Speed Study.

In Introduction to Traffic Engineering: A Manual for Data

Collection and Analysis, ed. B. Stenquist. Stamford, Conn.:

Wadsworth Group, PDF Note

SPOT SPEED STUDY WORKSHOP INSTRUCTION MANUAL

MassSAFE at the University of Massachusetts, Amherst

Governor’s Highway Safety Bureau, PDF Note

POLITEKNIK SULTAN AZLAN SHAH LABORATORY PROCEDURS

Civil Engineering Laboratory 3

Modul C4003

www.ctre.iastate.edu/PUBS/traffichandbook/2SpotSpeed.pdf www.ecs.umass.edu/.../Draft%20%20Spot%20Speed%20Study%20Training.pdf www.utm.edu/staff/mobadat/Courses/.../Spot%20Speed%20Study.ppt