Group 3Mohhammad Afsar Sujon

Traffic Speed Studies

2

Types of Speed Studies

July 22, 2012 Traffic Speed Studies

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

Travel Time 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

Specific Objectives of Traffic Speed StudyDetermine Vehicle Spot Speed

During Survey Period

Plot Histogram, Frequency Curve & Cumulative

Frequency Curve

Determine Weighted Average Speed, Pace, modal Speed, speed Limit, design

Speed

Determine Time Mean Speed(Vt) & Space Mean

Speed(Vs),and Proof Vs < Vt

Proof The Wardrop Relationship Between Time

Mean Speed(Vt) & Space Mean Speed(Vs),

Find Delay Time & Cost Of Delay

Draw Speed –Flow Curve

Scope of Traffic 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.

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Speed Determining Methods

July 22, 2012

STOPWATCH METHOD

RADAR METER METHOD

PNEUMATIC ROAD TUBE METHOD

For the unavailability of Radar & Pneumatic Road Tube method we had to use Stopwatch.

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Survey Area

July 22, 2012

Panthapath-Green road intersection and Panthapath-Mirpur Road intersection

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

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Histograms of vehicles

July 22, 2012

15 20 10 5 25 30 40 35

0102030405060

( Panthopath to Russel-square )

Bin

Freq

uenc

y

15 20 25 10 30 5 35 40 More

0

10

20

30

40

( Russel-square to Panthopath )

BinFr

eque

ncy

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Frequency distribution curve

0 5 10 15 20 25 30 35 40 45 50 55 60 65 7005

10152025

(Panthopath To Russel Square)

% Frequencies

July 22, 2012

0 5 10 15 20 25 30 35 40 45 50 55 60 65 700102030 (Russel Square To Panthopath)

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Cumulative frequency distribution curve

July 22, 2012

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70020406080

100 (Panthopath to Russel-square)

Cumulative% Frequencies

0 5 10 15 20 25 30 35 40 45 50 55 60 65 700255075

100(Russel-square to Panthopath)

TRAFFIC SPEED STUDIES11

Tabular data analysis Data obtained from Group 1, 2, 3 (Panthopath to Russel-square)

Speed groups (mph)

Mean of speed

group, v (mph)

Frequency, f

% frequency

Cumulative frequency f x v (v-ū)² f x (v-ū)²

0-4 2.00 0.00 0.00 0.00 0 236.97 0.004-8 6.00 5.00 5.05 5.05 30 129.82 649.11

8-12 10.00 15.00 15.15 20.20 150 54.67 820.0612-16 14.00 22.00 22.22 42.42 308 11.52 253.4116-20 18.00 23.00 23.23 65.66 414 0.37 8.4520-24 22.00 23.00 23.23 88.89 506 21.22 487.9624-28 26.00 6.00 6.06 94.95 156 74.06 444.3928-32 30.00 3.00 3.03 97.98 90 158.91 476.7432-36 34.00 2.00 2.02 100.00 68 275.76 551.5236-40 38.00 0.00 0.00 100.00 0 424.61 0.00

∑   99.00     1722 1387.92 3691.64

ū=∑f x v/ ∑f 17.39   

July 22, 2012

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Tabular data analysis Data obtained from Group 4, 5, 6 (Russel-square to Panthopath)

Speed groups (mph)

Mean of speed

group, v (mph)

Frequency, f

% frequency

Cumulative frequency f x v (v-ū)² f x (v-ū)²

0-4 2.00 0.00 0.00 0.00 0 300.81 0.004-8 6.00 3.00 3.03 3.03 18 178.06 534.17

8-12 10.00 8.00 8.08 11.11 80 87.31 698.4512-16 14.00 16.00 16.16 27.27 224 28.56 456.8916-20 18.00 42.00 42.42 69.70 756 1.81 75.8420-24 22.00 41.00 41.41 111.11 902 7.06 289.2824-28 26.00 11.00 11.11 122.22 286 44.31 487.3628-32 30.00 7.00 7.07 129.29 210 113.56 794.8932-36 34.00 0.00 0.00 129.29 0 214.81 0.00

∑   128.00     2476 976.25 3336.88ū=∑f x v/ ∑f 19.34    

July 22, 2012

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% Frequencies

July 22, 2012

0 5 10 15 20 25 30 35 40 45 50 55 60 65 700

5

10

15

20

25

% Frequencies

Modal speed= 23 Kmph

pace= 20~35 Kmph

Figure-: Pace & modal speed (Panthopath to Russel-aquare )

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Cumulative% Frequencies

July 22, 2012

0 5 10 15 20 25 30 35 40 45 50 55 60 65 700102030405060708090

100

Cumulative% Frequencies

98th percentile= 47 kmph

85th percentile= 35kmph

15th percentile= 16kmph

Figure-: Determination of Speed limit, design speed (Panthopath to Russel-square )

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Relationship between Space Mean Speed and Time 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 0.005-10 7.50 4 30.00 0.53 146.89

10-15 12.50 39 487.50 3.12 43.8215-20 17.50 14 245.00 0.80 217.3320-25 22.50 6 135.00 0.27 479.5425-30 27.50 2 55.00 0.07 388.6530-35 32.50 0 0.00 0.00 0.00Total   65 952.50 4.79 1276.23

July 22, 2012

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 3.60496.8

4

5-10 7.5 18 135 2.40106.2

9

10-15 12.5 16 200 1.28105.6

8

15-20 17.5 24 420 1.371375.

3220-25 22.5 0 0 0.00 0.0025-30 27.5 0 0 0.00 0.0030-35 32.5 0 0 0.00 0.00

35-40 37.5 2 75 0.051520.

21

Total   69 852.5 8.703604.

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 So, for this direction Vs < Vt

Time mean speed, Vt = ∑f*V / ∑f = 852.5/69 = 12.35 mphSpace Mean Speed, Vs = ∑f/∑(f/V) = 69/8.70 = 7.93 mphSo, for this direction Vs < Vt

So,Vs < Vt

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The Wardrop Relationship Between Time Mean Speed And The Space Mean Speed

July 22, 2012

# 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.

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Delay StudyPanthopath- Russell Square

Car 3- wheeler Bus Motorcycle

Free flow Speed(mph) 20.00 15.00 18.00 25.00Average Speed(mph) 15.51 12.21 12.53 16.49

Delay from Free Flow Speed(mph) 4.49 2.79 5.47 8.51Delay (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 25.00Average Speed(mph) 11.78 10.71 11.63 13.05

Delay from Free Flow Speed(mph) 8.22 4.29 6.37 11.95Delay (hr/km) 0.08 0.14 0.10 0.05

July 22, 2012

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Value of Travel Time (VOT) and Vehicle Operating Cost (VOC)

Vehicle Type Bus Car 3- wheeler MotorcycleFin 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

Hourly VOC for 2012/13

Item Cost Unit Bus Car 3- wheeler Motor CycleUnit 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 1309Maintenance 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 22Fuel cost Diesel Tk per liter 61 58 65 43 46 38 46 38Fuel cost petrol Tk per liter 85 72 76 62 76 62 76 62Lubricant cost Tk per liter 270 198 230 184 230 184.00 230 184

Estimated factor for VOC calculation 2012/13

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Value of Travel Time (VOT) and Vehicle Operating Cost (VOC)

Vehicle Type Bus Car 3- wheeler Motorcycle  Fin Eco Fin Eco Fin Eco Fin Eco

Diesel million Tk. 2.4 1.9 1.0 0.8 1.5 1.2 0.5 0.4

Petrol million Tk. 2.4 1.8 1.1 0.9 1.6 1.3 0.5 0.4

July 22, 2012

VOC calculation table

Vehicle Bus Car 3- wheeler MotorcycleAverage

Occupancy 40 4 4 1.1VOT

(Tk/passenger/hr) 40.7 78.8 33 58.4Total yearly delay

(hr) 642 1051 642.5 350.5Total VOT (million

Tk.) 1.1 0.33 0.08 0.02

Travel Time Cost of Passengers by Category of Vehicle

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Speed flow curve

Group No.

Flow (PCU/hr)

Speed (mile/hr)

Capacity (PCU/hr)

V/C ratio

1 905 16.21

4587

0.197297

2 917 12.39 0.199913

3 972 16.09 0.211903

July 22, 2012

Panthapath To Russell Square (E To W)

900 910 920 930 940 950 960 970 98005

101520

Panthapath to russell square

Speed (mile/hr)

Group No.

Flow (PCU/hr)

Speed (mile/hr)

Capacity (PCU/hr) V/C ratio

4 778 11.763807

0.204360.24402

45 929 13.990.24875

26 947 11.6

RUSSELL SQUARE TO PANTHAPATH (W to E)

7607808008208408608809009209409600

5

10

15Russell square to panthapath

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RecommendationsAutomatic 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

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Scope for Further Study

July 22, 2012

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.