speed spot studies
DESCRIPTION
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CC 503 TRAFFIC ENGINEERING
APPRECIATION
Thanks God, we give thanks to the Almighty for His grace and we can set up a report entitled
‘Traffic Engineering (CC 503)'. Appreciation and gratitude goes to Mr. Syed as lecturer traffic
engineering for their help, cooperation, guidance, advice and practical ideas that poured along
the run.
Thankfully we have colleagues who help others and help each other work, here are our group
members Roffandi, Luqman, Nurul Shafiqa, Asyikin, Effah and Amiera are always striving to
complete this traffic engineering work.
Moreover, not least thank you to friends, colleagues and all those who have helped us either
directly or indirectly. Hopefully reports this produced a certain extent helped to increase the
effectiveness student learning and enhance students' knowledge in the subjects studied civil
engineering in general and in particular traffic engineering.
Thank you.
SPEED SPOT STUDIES 1
CC 503 TRAFFIC ENGINEERING
INTRODUCTION
Speed is an important transportation consideration because it relates to safety, time,
comfort, convenience, and economics. 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.
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.
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.
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OBJECTIVE
SPOT SPEED STUDY
To determine the speed characteristics of traffic at the location. Spot speed studies are
vital for measuring different variables and factors needed in the design and analysis of the
highway system. Observed speeds are used for capacity analysis, geometric design, safety
measures, speed trends and assessment. Speed studies aid in the decision making processes and
in before-and-after studies to assess the effectiveness of roadway modifications. Also, speed
observations help determine whether the roadway is in need of new law enforcement,
realignment, or reconstruction. Spot speed data have a number of safety applications, including
the following: determining existing traffic operations and evaluation of traffic control devices,
establishing roadway design elements, and measuring effectiveness of traffic control devices or
traffic programs, including signs and markings, traffic operational changes, and speed
enforcement programs. Because of the importance of such speed studies, data has to be collected
properly and presented effectively.
Therefore required to select a section of a road outside the university campus and away
from close intersections and unusual traffic activities. Information about the selected section of
the road is gathered such as section speed, number of lanes, and general description of location.
Data is to be collected during off peak periods on a week day.
SPEED SPOT STUDIES 3
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THEORY
Figure 1 : Positions of Students and flags
Spot speed data are gathered using methods :
Stopwacth method Radar meter method Pneumatic road tube method. Measuring wheel Two Flags Safety Vest
SPEED SPOT STUDIES 4
V V VEHICLE
Student A 3Students Student B
Positions of Students and flags
CC 503 TRAFFIC ENGINEERING
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. The stopwatch method can be used to successfully complete a spot speed study using a small sample size taken over a relatively short period of time. The stopwatch method in a quick and inexpensive method for collecting speed data.
Figure 2 : Stopwatch Spot Speed Study Layout
Merlimau town noticed a large number of traffic jams in the morning along Main Street. The city decided to conduct a speed study to see how the speed of the vehicle compared to the recorded the speed limit. The police department offered their radar meter to be used and so the city decided to meter using radar to conduct spot speed. The city has determined that it will not need help from members of local law enforcement
Figure 3 : Example Radar Meter Spot Speed Study Layout
SPEED SPOT STUDIES 5
CC 503 TRAFFIC ENGINEERING
APPARATUS
The following apparatus is required. No. APPARATUS FIGURE DESCRIPTION
1. Stop Watch
-To make that experiment-To support the load
2. Measuring Wheel-To record the value
of the load.
3. Two Flags-To hang the load
4. Safety Vest-To support and hold the load.
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PROCEDURE
(After done setup apparatus, follow the procedures below)
Test Procedure :
No. Procedure Picture
1. Identify the spot at which the speed data will be collected.
2. Use the measuring wheel to get a 100m distance..
3. Record the times taken for 20 passenger cars in the Form.
4. Based on the Form , determine the mean, maximum and minimum speed of vehicles according to their class. Comment on your findings.
SPEED SPOT STUDIES 7
CC 503 TRAFFIC ENGINEERING
5. Transfer and calculate for the relevant data into the Frequency Form.
6.Plot the following :a) Frequency Histogram ( Percentage of vihicles vs. Speed)b) Frequency Distribution Curve (Percentage of vihicles vs. Speed)c) Cumulative Frequency Distribution Curve (Cumulative frequency vs. Speed)
7.Dtermine the following speed characteristics:a) Mean speedb) Median sppedc) Mode class (speed)d) 85-th Percentile speede) Standard deviation
8. Comment your findings.
9. Does your findings justify the problems of speeding at the location? If it does what are your recommendations.
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RESULTS & CALCULATION
Calculation
a) Class interval = R
1+3.322 logn
= 84.31−37.821+3.322 logn
= 8.74 ≈ 9
b) Arithmetic mean speed , x=∑fvn
= 1205.18
20
= 60.259
c) Median = L+
( n2−fl )×C
[ fm ]
= 54.81+
( 202−30 )×9
35 = 49.67
d) Standard deviation, s = √¿¿ = √¿¿ = 11.30
SPEED SPOT STUDIES 9
CC 503 TRAFFIC ENGINEERING
Graph
41.80 50.31 59.31 68.31 77.31 86.310
1
2
3
4
5
6
7
8
Frequency Histogram for Spot Speed Studies
speed, (km/hr)
freq
uenc
y of
car
30.00 40.00 50.00 60.00 70.00 80.00 90.000
5
10
15
20
25
30
35
40
Frequency Distribution Curve
speed (km/hr)
perc
enta
ge o
f tot
al o
bser
vatio
n
SPEED SPOT STUDIES 10
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30.00 40.00 50.00 60.00 70.00 80.00 90.000
20
40
60
80
100
120
Percentage Of Cumulative Frequency
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DISCUSSION
A typical layout for conducting a spot speed study using a stopwatch. When selecting a
location and layout, care must be exercised so that the observer can clearly see any vertical
reference posts. The observer should be positioned higher than the study area and be looking
down. The position could be on a bridge or a roadway back slope.
The observer should use reference points to aid in collecting the elapsed time it takes a
vehicle to travel through the study area. The reference point to start timing may be a brightly
coloured vertical post. The reference point to end timing may be a tree or a signpost in the
observer’s sight line. An accurate sketch of the site should be documented, including number of
lanes, position of observer, and description of reference points.
SPEED SPOT STUDIES 12
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RECOMMENTDATION
Other reason happened outcome of experiment inaccuracy was:
Essential to this initial step is to identify the reason for conducting the study and nature of
the problem to be evaluated. Other considerations for the study plan are the date and time during
which the study should be completed, and the number of vehicles that should be observed as part
of the study. The timing of the study should be consistent with the reason for conducting the
study. For example, if the study is being completed to determine if speed complaints are valid
during the evening rush hour, then the study should be completed during the evening rush hour.
Literature suggests that speed data be collected for a minimum of one hour and observe at least
30 vehicles, however depending upon the type of technology used to complete the study, and the
complexity of the study, sample sizes and durations can often include thousands of vehicles over
multiple 1 days. Once the plan is completed, the study can be carried out and the data can be
evaluated as outlined in the steps below.
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CONCLUSION
Field traffic studies strengthened the traffic theories presented in the class room. Spot
speed study and intersection analysis and signal assessment helped students gain the following
benefits: Spot speed study and intersection analysis and signal assessment field study
implementations, familiarity with standard procedures and standard forms, data presentation
techniques, data analysis, field experience and applications, group work, professional
presentation skills, interpretations of results, and professional software implementation.
Students presented their suggested solutions to improve the studies intersections such as
signal timing modifications, intersection widening, geometric adjustments, and realignments.
This paper described the minimum requirements for establishing the aforementioned studies and
intended objectives. Future plans are to develop an additional three-hour laboratory to
accompany the transportation engineering class. The laboratory will include additional studies
and projects that will embrace the transportation material taught in the classroom environment..
SPEED SPOT STUDIES 14
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REFERENCES
Book References
Transportation Engineering (KAS 4172) lecture notes. Currin, Thomas R., Introduction to traffic engineering, a manual for data collection and
analysis, Brooks/Cole, Pacific Grove, CA, 2001.
Internet References
http://www.roadtraffic-technology.com http://www.popcenter.org/learning/speeding.html http://www.ctre.iastate.edu/pubs/traffichandbook/
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APPENDIX
SPEED SPOT STUDIES 16