Estimation of Capacity for Multi-LaneDivided Inter-Urban Highways using

Videography Technique of DataCollection

Naveen Sharma, Dr. P.K Sarkar, Dr. S. Velmurugan

Focus of Presentation

Introduction

Review of Pervious Speed - Flow and Capacity Studies

Study Objectives and Scope

Overview of Test Sections

Data Collection

Methodology

Speed - Flow Equations (Traditional and Simulation)

Capacity Estimation (Traditional and Simulation)

Inferences

Limitations and Future Work

Introduction

Transport Sector ofIndia

Plays Significant role in enhancing the Economic Growth of any Country

Road Sector is the Major component of the transport in India

Roadways are the dominant part for the movement of goods and passenger traffic andcarries about 70 % goods and 85% of Passenger trafficTraffic grows at the rate of 7 to 10% per annum while the vehicle population growth -12% perannum40% of total traffic carried by Inter – Urban Highways, which is only 1.7% of total roadnetworkExisting Road Infrastructure is Highly inadequate in comparison with the situation ofdeveloped world

Introduction(Cont….)

Capacity of Inter –Urban Highways inIndia

Connectivity through highways is not the only requirement, capacity of highways are equallyimportant for achieving the envisaged economic growth of the nationGovt. of India has taken initiatives to determine the capacity of Inter-urban Highways in India

Indian Road Congress (IRC) provides standards for assessing the capacity on highways inIndian conditionThe capacity standards for multi-lane highways are Tentative

A scientific and systematic procedure to estimate Speed - Flow relationships and roadwaycapacity is required.In which Microscopic Simulation Techniques can help in improving the accuracy of Capacityestimation procedure

A study has been initiated by Planning Commission titled Development of Indian Highway CapacityManual (Indo-HCM) under the aegis of CSIR (Centre for Scientific and Industrial Research) . This study isaimed to prepare capacity standards for all classes of highways in India.

This research is a Part of above said Endeavor

Objective & Scope of the Study

Objective• To analyze traffic flow data collected on Multi-lane divided Inter-Urban Highways under varying roadway and

traffic conditions using Videography technique of data collection.• To study the effect of influencing parameters of traffic composition & vehicular Speed on capacity of Multi-lane

divided Inter-Urban Highways under mixed traffic conditions.• To estimate free flow speeds on Multi-lane divided Highways.• To determine Dynamic Passenger Car Unit of various types of Vehicle on Multi-lane divided Inter-urban

Highways.• To develop the speed-flow relationship for mixed traffic using Traditional & Microscopic simulation Technique.• Finally to evolve road capacity for multi-lane divided Inter-Urban Highways.

Scope• Estimation of Capacity for multi-lane divided Inter-Urban Highways, mainly Four-lane and Six-lane

Review of Speed-Flow and Capacity Studies

International Studies• The Highway Capacity Manual (HCM) describes

roadway capacity under ideal conditions andthen estimates practical capacities underprevailing conditions in the field (TRB, 2000)

• The Danish method is a modification of U.S.HCM to suit Danish conditions (Nielsen andJorgensen, 2008)

• In Finland and Norway too, US-HCM 2000 (TRB,2000) was followed with minor modifications tosuit the local conditions

• Swedish method - Similar to the US-HCM (1995)& uses the 1995 HCM adjustment factors for theroadway width, whereas other adjustmentsfactors are mostly omitted

• The Swedish method yielded higher capacityestimates and the estimated capacity of four-lane divided highways was 4200 PCUs/hour perdirection (Luttinen and Innamaa, 2000)

Indian Studies• Road User Cost Study (1982, 1991 & 2001) - CRRI,

LRK

• IRC-64 (1990) - Recommended DSV of 40,000PCUs for the four-lane divided carriageways inplain terrain

• URUCS-2001 - Suggested capacity of 70,000 -90,000 PCUs/day

• Shukla (2008) - Mixed traffic flow behavior -Simulation model for the observed traffic flow toestimate roadway capacity for four lane dividedcarriageways; estimated as 4770 vehicles/hour(vph) in each direction

• In addition, more than 12 research studies havebeen carried out during the last decade.

Overview of Test Sections

SIX LANE DIVIDED SECTIONb/w CHAINAGE 40-41KMFROM DELHI ON NH-1

FOUR LANE DIVIDEDSECTION b/w CHAINAGE 37--

38KM TOWARDS MEERUTON NH-58

Glimpse of Test Sections

Selection Procedure

• Section is so selected that it shall

satisfy the base condition like

Surface condition, Median etc.

• Section shall be straight without the

influence of any intersection etc. for

at least 500 m on either side.

Data Collection and Decoding

Data Collection• Data collection being carried out for a period of

12 hours with the help on videography technique

• A longitudinal trap length of 60 m is made usingmeasuring wheel. Alternatively, White tape isused to mark the Entry & Exit of Trap length

• For Video recording camera was placed at aheight of 15 m from the ground in both thedirection by positioning the camera at a vintagepoint covering the entire trap length.

Decoding• For Decoding, vehicles are divided into fifteen

categories and data on volume, space mean speed,headway and lateral clearance by individual vehiclesduring every five minute time interval beingextracted from video by running the video on computer screen with the

classification of the vehicles in to 15 different categories

doing 5-5 Minutes interval classified volume count foreach Lane with each category passing through the firstline of the trap being recoded & tabulated

• Based upon the time taken by vehicles in eachcategory to cover the trap length of 60 m speed iscalculated (km/hr) by using the relationship V=L/T

Methodology

In order to achieve the above envisaged objective and ease of understanding,this study is divided in to three main parts viz.

• Free flow speed study,

• Dynamic PCU study and

• Speed - Flow study

The details of methodology and results obtained have been discussed in thesubsequent sections.

This Spread Ratio is used to check the validityof data if it is unity then it shows that theestimated Frequency curve is truly normal. Itwill tend to deviate from the normaldistribution as SR deviates from the unity.

Methodology for Free Flow Speed Study

• For the calculation of Free-Flow speed, recorded video replayed and thosecases are only considered which are occurring in free flow condition

• Normal Distribution

• Percentile Speeds (85th , 50th and 15th)

• Spread Ratio (SR) = (V85 - V50) / (V50 - V15)

• Statistical Results

• Normal Approximation Test

• Regression Analysis

Typical Normal Distribution Curve

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Speed(km/hr)

Cu

mu

lati

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Pe

rce

nt

Mean 84.15StDev 15.60N 353

Histogramof Speed(km/hr)Normal

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Speed(km/hr)

Perc

ent

85

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68.0

Mean 84.15StDev 15.60N 353

Empirical CDFof Speed(km/hr)Normal

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Mean 84.15StDev 15.60N 353

Histogramof Speed(km/hr)Normal

Typical Distribution of small Car free speed in a Six LaneDivided Carriageway

Results obtained in Free Flow Speed StudyVehicle Type Sample Size Avg. Speed * V15

* V50* V85

* Max. Speed* SD* SRTW 267 62 48.29 62.22 76.16 100 13.45 1.000718

Auto 42 42 34.89 41.6 48.32 64 6.78 1.00149M.4-W 42 57 45.7 55.77 65.84 77 9.71 1

Small Car 445 73 57.23 72.68 88.12 120 14.9 0.999353Big Car 408 76 58.9 76.3 93.7 125 16.81 1

Bus 147 65 53.46 64.84 76.22 91 10.98 1M.Bus 54 62 46.9 62.26 77.61 93 14.82 0.999349

LCV 173 58 47.91 57.95 67.98 82 9.68 0.999004HCV 138 53 41.08 52.86 64.64 80 11.37 1MAV 76 64 46.17 54.52 62.86 97 8.05 0.998802

Vehicle Type Sample Size Avg. Speed * V15* V50

* V85* Max. Speed* SD* SR

TW 98 56 39.4 56.1 72.7 131 16.06 0.994012Auto 37 43 32.45 43.22 53.99 61 10.39 1

M.4-W 36 58 45.92 58.03 70.14 79 11.68 1Small Car 353 84 68 84.1 100.3 137 15.6 1.006211

Big Car 451 86 69.2 86.5 103.7 138 16.62 0.99422Bus 97 79 65.87 79.25 92.62 126 12.91 0.999253

M.Bus 47 84 67.17 84.23 101.28 115 16.45 0.999414LCV 157 58 46 63.8 81.7 119 17.23 1.005618HCV 378 53 52.3 69.4 86.5 111 16.5 1MAV 66 65 49.15 65.63 82.11 101 15.9 1

*=km/hr

Four lane DividedCarriageway

Four lane DividedCarriageway

Normal distribution curve described the speed distributions satisfactorily in most of the vehicle types since the SRvalue is ranging around 1.0 (from 0.990 to 1.01) demonstrating that SR is well within the limits.

Free speeds on six Lane is more than on four Lane divided Carriage way

Free Flow Speed Characteristics Cont.Free speeds of Goods vehicle Marginallyincreased from Four Lane Carriageway tosix Lane Carriageway

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TW Auto Small Car Big Car Bus LCV HCV MAV M.4-W M.Bus

62

42

73 76

6558

53

6457

6256

43

84 8679

5853

6558

84

Avg

. Fre

e Sp

eed(

km/h

r)

Four- Lane Divided Six-Lane Divided

Methodology for Dynamic PCU Study• The standard Static PCU factors for Indian condition provided by IRC and given in the code IRC: (64-

1990)

• PCU is complex parameter and depends upon all factors of geometry ,traffic operation and keeps onchanging with the conditions

• PCU factor has a great impact on the estimation of capacity for an highway, so to determine theimpact and to obtain the accuracy in Capacity Estimation, dynamic PCU is calculated in this study

• In this data on headway & Lateral clearance are decoded using a grid-formation (A grid with 2 m oflateral & longitudinal gap was formed) on the entire trap length using video editing tools as shown inFigure below. The average no. of samples taken for each vehicle category was 50.

Methodology and Conceptual Model forDynamic PCU

As per the definition PCU may be consider as measure of relative space requirement of a vehicle class compared to thatpassenger car under specified set of conditions. To determine the variation in PCU values for a vehicle type, thefollowing factors are considered like Influence area of each vehicle, Traffic composition, Speed of each category ofvehicle, Headway, Lateral clearance

As PCU of a vehicle is believed to be directly proportional to the ratio of speed and inversely proportional to the spacerequirement od vehicle w.r.t car.=

= /

Where, = equivalent passenger car unit of vehicle i, V = clearing speed of car (km/hr), = clearing speed of vehicle i (km/hr), =projected rectangular plan area of car (m2), = projected rectangular plan area of vehicle i (m2).

Conceptual Model forDynamic PCU Calculation

The variation of Traffic volume on 4-Lane Divided Inter-Urban Highway using Dynamic PCU was found ranging between 10-20%Whereas in case of 6-Lane divided Inter-urban highway it ranging from 2-4%

Results obtained in Dynamic PCU Study

Dynamic PCU valueObtained after Analysis

Methodology for Speed Flow Study using TraditionalModel

RoadwayCapacity

Capacity

Congested/ Queuing

Uncongested

VQueue

VCap

Speed (v)

Flow (F)

Vf

FCap

Linear Equation BPR Equation

Exponential Equation

Equation Functional Form Comments

Linear v = - x + β Not always advisable; Reaches zero speed at high F/Fcap

Logarithmic v = - ln x+β Not always advisable; Has no value at x = 0 (the logarithm of“x” approaches negative infinity).

Exponential v = vf exp(-βx) Has all the required traits for equilibrium assignment

Power v = /xβ Not always advisable; It goes to infinity at F/Fcap at x = 0.

Polynomial v = -x2 –βx + γ Not always advisable; It reaches zero speed at high F/Fcap

BPR v = vf/(1+(x)β) Has all the required traits for equilibrium assignment

Akcelik V=L/[L/vf+0.25{(x-1) + SQRT{(x-1)2+x}}] Has all the required traits for equilibrium assignment.

Note:- v = Speed; , β and γ = Global Parameters for Equation; x = F/Fcap ratio; vf = Free - Flow Speed;F = Flow; Fcap =Capacity Flow; L = Link Length;

Results for Speed Flow Study using TraditionalModel

Using Traditional model the capacity for multi-lane divided Inter-Urban highway is found out, the speed-flow equation obtained are shown here

R² values rangingbetween 0.638-0.881,whichestimates that thefitting of curve wasgood.

Comparison of Free Flow Speed with Interceptof Speed-Flow Equation

Carriageway Vehicle TypeObserved Mean Free Speed

(Kmph)Intercept of Speed-Flow

Equation (Kmph)Error (%)

Four-Lane

TW 62 64.7 3%Auto 42 44.5 4%

M.4-W 57 59.2 4%Small Car 73 75 1%

Big Car 76 78 1%Bus 65 67 3%

Mini Bus 62 67 4%LCV 58 61 7%HCV 53 55 5%MAV 64 67 7%

Six-Lane

TW 56 59 5%Auto 43 46 3%

M.4-W 58 61 3%Small Car 84 82 1%

Big Car 86 89 1%Bus 79 83 5%

Mini Bus 84 88 2%LCV 58 61 3%HCV 53 55 1%MAV 65 69 6%

Since Error is rangingbetween 1-7%, thedeveloped speed-flowequations are showinggood result but it can berechecked usingComputer simulationbecause with thisapproach we are notgetting the lower curve(Congested Flow)

Capacity using Traditional Model

Four-lane divided Carriageway Six-lane divided Carriagewayy = -0.0088x + 74.245

R² = 0.7367

0102030405060708090

0 1000 2000 3000 4000 5000 6000 7000Stre

am S

peed

(km

/hr)

Flow Rate(PCU/hr)

Stream Speed vs Flow Graph forDPCU

Capacity=4850PCU/hr/dir

Methodology for the Speed Flow Study usingMicroscopic Simulation Model

• Simulation Model is developedusing VISSIM 5.4

• Calibrated and Validated• Traffic Volume• Speed

• Using the developed model,different traffic flows given asinput and speeds were predicted

• Developed Speed-Flow Model

Microscopic Simulation Model Validation usingTraffic Volume and Speed

Overall Error variesbetween 0-2%

Overall Error rangingbetween 1-4%

Calibration of Microscopic Simulation Model

Capacity using Microscopic Simulation Model

Four-lane dividedCarriageway

Six-lane dividedCarriageway

Capacity using Microscopic Simulation Model

Estimated Capacity using D PCUType Roadway Capacity

(PCU/hr/lane)

4-Lane 2250

6-Lane 2233

Estimated Capacities based on Traditional and Simulation Models reveals that roadway capacities from simulation is consideredto be more realistic as the estimated error reduced significantly compared to Traditional Model

Speed-Flow Equation of upper and lower curve for Four and Six-laneusing Microscopic Simulation Model

FOUR LANE DIVIDED INTER-URBANHIGHWAY

SIX LANE DIVIDED INTER-URBAN HIGHWAY

Curve STREAM SPEED VSFLOW USING

S PCU Eqn.

STREAM SPEED VSFLOW USING

D PCU Eqn.

STREAM SPEED VSFLOW USING

S PCU Eqn.

STREAM SPEED VSFLOW USING

D PCU Eqn.

UpperCurve

y = -0.0083x + 72.702R² = 0.6525

y = -0.0084x + 75.434R² = 0.6526

y = -0.0057x + 76.262R² = 0.6831

y = -0.0057x + 78.078R² = 0.6831

LowerCurve

y = 0.0085x + 2.051 R²= 0.7146

y = 0.0084x - 0.3655R² = 0.6928

y = 0.0059x + 1.4352R² = 0.7347

y = 0.0059x - 0.4668R² = 0.7347

Inferences

• Speed-Flow Equations are developed through Simulation Model• Capacities from simulation is considered to be more realistic as the estimated error in

simulation method reduced tremendously compared to traditional method• The difference in capacity value using Static & Dynamic PCU for multi-lane divided inter-

urban highways varies within the range of 5-7% of total capacity• The Capacity of 4-Lane Divided Inter- Urban Highway using simulation model is estimated

to be 2200 & 2250 PCU/lane/hr/dir coming Lower as compare to the capacity usingtraditional model , which is 2300 & 2425 PCU/lane/hr/dir using Staic & Dynamic PCU.

• The Capacity of 6-Lane Divided Inter- Urban Highway using simulation model is estimatedto be 2166 & 2233 PCU/lane/hr/dir coming higher as compare to the capacity usingtraditional model , which is 2133 & 2200 PCU/lane/hr/dir using Staic & Dynamic PCU.

• Capacity values and Speed flow equation arrived in this study can be regarded as handytool for the estimation of holding capacity of multi lane highways for upgrading the facilityby adding lanes

Limitation and Future Scope

Limitation• Study is limited to Two test sections only

• The traffic data collected through videographytechnique was only for one day

Future Scope• Assessment of lane change behaviour for Four-

lane and Six-lane through field observationsand model refinement can be done

• Study can be extended to the estimation ofCapacity for Two-lane and Eight-lane dividedInter-Urban highways

ThankYounaveensharma356@gmail.com