2. Types of Speed Studies
July 22, 2012 Traffic Speed Studies2
Spot Speed Studies
spot speed studies to measure
speeds at specific locations
# studies speeds at specific
locations
#determine the design speed
# aid in conducting safety studies
#analyze special operational
situations
TravelTime Studies
Travel time is the time taken by
a vehicle to cross a given
segment of a street or highway
#evaluate the effectiveness of
traffic improvements
#provide economic analyses of
alternatives
#evaluate trends in efficiency and
level of service
Speed Delay Studies
Delay is the time lost by a
vehicle due to causes beyond
the control of the driver
#identify problem areas
#determine the efficiency of a
route
#evaluate effectiveness of traffic
improvements
# provide economic analyses of
alternatives
3. Specific Objectives of Traffic Speed Study
DetermineVehicle
Spot Speed During
Survey Period
Plot Histogram,
Frequency Curve &
Cumulative
Frequency Curve
DetermineWeighted
Average Speed, Pace,
modal Speed, speed
Limit, design Speed
DetermineTime Mean
Speed(Vt) & Space
Mean Speed(Vs),and
Proof Vs <Vt
ProofThe Wardrop
Relationship Between
Time Mean Speed(Vt) &
Space Mean Speed(Vs),
Find DelayTime & Cost
Of Delay
Draw Speed –Flow
Curve
4. Scope ofTraffic Speed Studies
Establishing the
effectiveness of
new or existing
speed limits
Magnitudes,
classifications
and the time
and directional
split of vehicular
flows.
Time and
directional split of
vehicle is useful to
identify tidal flow.
Determining
appropriate speed
limits for
application
Investigation of
high-accident
locations at which
speed is
suspected to be a
contributing
cause to the
accident
experience.
Specific control
for the timing of
“yellow” and “all
red” intervals for
traffic signals,
placement of
signs, and
development of
signal
progressions.
5. Speed Determining Methods
July 22, 2012 Footer text here5
STOPWATCH METHOD
RADAR METER
METHOD
PNEUMATIC
ROADTUBE
METHOD
For the unavailability of Radar &
Pneumatic Road Tube method we had
to use Stopwatch.
6. Survey Area
July 22, 2012 Footer text here6
Panthapath-Green road intersection and Panthapath-Mirpur Road intersection
7. Spot speed
Average speed of individual
group from Panthopath to
Russel-square(mph)
Group 1 Group 2 Group 3 Average
directional
speed (mph)
18.43 16.38 19.48 18.10
Average speed of individual
group from Russel-square to
Panthopath(mph)
Group 4 Group 5 Group 6 Average
directional
speed (mph)
20.33 20.00 16.92 19.08
8. Histograms of vehicles
July 22, 2012 Footer text here8
0
10
20
30
40
50
60
15 20 10 5 25 30 40 35
Frequency
Bin
( Panthopath to Russel-square )
0
10
20
30
40
Frequency
Bin
( Russel-square to Panthopath )
15. Relationship between Space Mean Speed andTime Mean Speed
Speed
Group
(Mph)
Mean Speed
of Group,V
(Mph)
No. of
vehicles in
group, f
f*V f/V f(V-Vs)²
0-5 2.50 0 0.00 0.00 0.00
5-10 7.50 4 30.00 0.53 146.89
10-15 12.50 39 487.50 3.12 43.82
15-20 17.50 14 245.00 0.80 217.33
20-25 22.50 6 135.00 0.27 479.54
25-30 27.50 2 55.00 0.07 388.65
30-35 32.50 0 0.00 0.00 0.00
Total 65 952.50 4.79 1276.23
July 22, 2012 Footer text here15
Panthopath To Russel Square Russel square to Panthopath
Speed
Group
(Mph)
Mean Speed
ofGroup,V
(Mph)
No. of
vehicles in
group, f
f*V f/V f(V-Vs)²
0-5 2.5 9 22.5 3.60 496.84
5-10 7.5 18 135 2.40 106.29
10-15 12.5 16 200 1.28 105.68
15-20 17.5 24 420 1.37 1375.32
20-25 22.5 0 0 0.00 0.00
25-30 27.5 0 0 0.00 0.00
30-35 32.5 0 0 0.00 0.00
35-40 37.5 2 75 0.05 1520.21
Total 69 852.5 8.70 3604.34
Time mean speed, Vt = ∑f*V / ∑f
= 952.50/65
= 14.65 mph
Space Mean Speed, Vs = ∑f/∑(f/V)
= 65/4.79
= 13.57 mph
Time mean speed, Vt = ∑f*V / ∑f
= 852.5/69
= 12.35 mph
Space Mean Speed, Vs = ∑f/∑(f/V)
=
69/8.70
So,Vs < Vt
16. The Wardrop Relationship Between
Time Mean Speed AndThe Space Mean Speed
July 22, 2012 Footer text here16
#Time mean speed,Vt = ∑f*V / ∑f
= 852.5/69
= 12.35 mph
# Space Mean Speed,Vs = ∑f/∑(f/V)
= 69/8.70
= 7.93 mph
#Variance, Sd² = ∑f(V-Vs)²/(∑f-1)
= 3604.34/ 68
= 53 mph
#Vs + Sd²/Vs = 7.93 + 53/7.93
= 14.61 > (Vt =12.35 )
Russel-square- Panthopath Direction
#Time mean speed,Vt = ∑f*V / ∑f
= 952.50/65
= 14.65 mph
# Space Mean Speed,Vs = ∑f/∑(f/V)
= 65/4.79
= 13.57 mph
#Variance, Sd² = ∑f(V-Vs)²/(∑f-1)
= 1276.23/ 64
= 19.94mph
#Vs + Sd²/Vs = 13.57 + 19.94/13.57
= 15.04 >(Vt =14.65 )
Panthopath- Russel-square Direction
The Wardrop Relationship (Vs + Sd²/Vs > Vt ) Between Time Mean Speed
And The Space Mean Speed Which Has Been Found Right.
17. Delay Study
Panthopath- Russell Square
Car 3- wheeler Bus Motorcycle
Free flow Speed(mph) 20.00 15.00 18.00 25.00
Average Speed(mph) 15.51 12.21 12.53 16.49
Delay from Free Flow Speed(mph) 4.49 2.79 5.47 8.51
Delay (hr/km) 0.14 0.22 0.11 0.07
Russell Square- Panthopath
Car 3- wheeler Bus Motorcycle
Free flow Speed(mph) 20.00 15.00 18.00 25.00
Average Speed(mph) 11.78 10.71 11.63 13.05
Delay from Free Flow Speed(mph) 8.22 4.29 6.37 11.95
Delay (hr/km) 0.08 0.14 0.10 0.05
July 22, 2012 Footer text here17
18. Value ofTravelTime (VOT) andVehicle Operating Cost (VOC)
VehicleType Bus Car 3- wheeler Motorcycle
Fin Eco Fin Eco Fin Eco Fin Eco
1 hour delay cost (assuming
quarter liter Diesel fuel + 1/15
liter of lubricant consumed)
395.92 311.48 162.98 138.35 155.67 128.53 154.57 122.43
1 hour delay cost (assuming
quarter liter Petrol fuel + 1/15
liter of lubricant consumed)
393.47 302.48 183.48 149.65 162.17 137.53 162.19 129.53
July 22, 2012 Footer text here18
HourlyVOC for 2012/13
Item Cost Unit Bus Car 3- wheeler Motor Cycle
Unit Costs Fin Econ Fin Econ Fin Econ Fin Econ
Purchase cost of vehicle Tk'000 per vehicle 4456 3815 2292 1399 327 195 137 195
Cost of new tire Tk per tire 25375 17780 4163 2932 1863 1309 1181 1309
Maintenance labor cost Tk per hour 92 86 82 66 82 66 82 66
Overhead cost Tk '000 per annum 1898 1468 48 39 19 23 19 23
Crew cost Tk per hour 50 40 33 28 26 22 26 22
Fuel cost Diesel Tk per liter 61 58 65 43 46 38 46 38
Fuel cost petrol Tk per liter 85 72 76 62 76 62 76 62
Lubricant cost Tk per liter 270 198 230 184 230 184.00 230 184
Estimated factor forVOC calculation 2012/13
19. Value ofTravelTime (VOT) andVehicle Operating Cost (VOC)
VehicleType Bus Car 3- wheeler Motorcycle
Fin Eco Fin Eco Fin Eco Fin Eco
Diesel millionTk. 2.4 1.9 1.0 0.8 1.5 1.2 0.5 0.4
Petrol millionTk. 2.4 1.8 1.1 0.9 1.6 1.3 0.5 0.4
July 22, 2012 Footer text here19
VOC calculation table
Vehicle Bus Car 3- wheeler Motorcycle
Average Occupancy 40 4 4 1.1
VOT (Tk/passenger/hr) 40.7 78.8 33 58.4
Total yearly delay (hr) 642 1051 642.5 350.5
TotalVOT (millionTk.) 1.1 0.33 0.08 0.02
TravelTime Cost of Passengers by Category ofVehicle
20. Speed flow curve
Group
No.
Flow
(PCU/hr)
Speed
(mile/hr)
Capacity
(PCU/hr)
V/C
ratio
1 905 16.21
4587
0.19729
7
2 917 12.39
0.19991
3
3 972 16.09
0.21190
3
July 22, 2012 Footer text here20
PanthapathTo Russell Square (EToW)
0
5
10
15
20
900 920 940 960 980
Panthapath to russell square
Speed
(mile/hr)
Group
No.
Flow
(PCU/hr)
Speed
(mile/hr)
Capacity
(PCU/hr)
V/C ratio
4 778 11.76
3807
0.20436
0.2440245 929 13.99
0.2487526 947 11.6
RUSSELL SQUARETO PANTHAPATH (W to E)
0
5
10
15
0 200 400 600 800 1000
Russell square to panthapath
21. Recommendations
Automatic data
collection process
must be used for
more realistic
information.
Manual count
method must be
done by trained
enumerators.
Huge amount of
data should be
collected for data
combination
between different
group.
The result of the
study suggests that
traffic control
system have to
improve for smooth
flow.
Volume study must
be done before
speed study.
Speed & delay
studies must be
done carefully for
cost & benefit
calculation of a
project.
July 22, 2012 Footer text here21
22. Scope for Further Study
July 22, 2012 Footer text here22
This speed study was
completed by un-skilled
enumerators that leads to
some error in data collection
process.
Data collected by manual
method is unreliable and
irreversible. For more
representatives and reliable
data automatic data
collection method should be
followed.
Data were collected for
short-period (30 minute)
can’t implies flow
characteristics of the road. If
3days continuous data were
collected, that would be
much more representative
and realistic.
