Conversation of at Grade Signalized Intersection in to Grade Separated Intersection

7/21/2019 Conversation of at Grade Signalized Intersection in to Grade Separated Intersection

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IJIRST – International Journal for Innovative Research in Science & Technology| Volume 2 | Issue 05 | October 2015

ISSN (online): 2349-6010

All rights reserved by www.ijirst.org 113

Conversation of at Grade Signalized Intersection

in to Grade Separated Intersection

Hiren Patel

Assistant Professor

Department of Civil Engineering

SAL Institute of Technology and Engineering Research, Ahmedabad

Abstract

The urban traffic congestion has become a global phenomenon. Rapid urbanization and industrialization have caused an

unprecedented revolution in growth of vehicles all over the world. This study presents, grade separation (over bridge) is provide

in place of at grade signalized intersection. Ahmedabad city of Gujarat state is taken as study city. Shivaranjani signalized

intersection on 132 ft ring road in the city of Ahmedabad is selected as a case study intersection. Various types of data are

collected such as classified volume counts, signal cycle length, green time, phase plan etc. and number of lanes, lane width,

grade, lane groups etc as a part of geometric data. The flow rate, saturation flow rate and its adjustment factors, capacity, volume

to capacity ratio, critical lane group volume to capacity ratio, delay for lane groups, approaches and intersection as whole and

delay comparison with level of service are calculated. This study proves that shivaranjani intersection must be required to

convert in to grade separation.

Keywords: Capacities, Congestion, Delay, Flow, Intersection, Lanes, Signal

_______________________________________________________________________________________________________

I. INTRODUCTION – URBANIZATION

In 1950, 30 % of world population lives in an urban area. In 2000, 47 % of world population lives in an urban area. These will

increase up to 60 % in year 2030. This figures show that people want to live in an urban area. In India 30% of the population

lives in urban area. In some progressive states like TamilNadu, it is 43.86%, second is Maharastra, it is more than 42%, and third

is Gujarat, it is more than 37%. This urbanization is happen due to rapid industry growth and hence population density increased

in cities.

II. PROBLEM STATEMENT

Rapid urbanization and industrialization have caused an unprecedented revolution in growth of vehicles all over the world. Due

to fast growing vehicular traffic, cities become congested and road links, intersections become saturated, busy and supply service

is above its capacity. This urban traffic congestion has become a global phenomenon. So, the problems at intersection are to

require effective mode of controls to regulate the traffic and maintain optimum delay for congestion of the traffic on the

intersection.

III. OBJECTIVE

Objective of this study is to please the conditions for conversation of at-grade signalized intersection in to grade separated

intersection.

Cri teri a for Provision of Grade – Separated IntersectionA.

1)

Certain at-grade intersections which have reached the maximum capacity and where it is not possible to improve the

capacity further by retaining the at-grade crossing.

2) At certain locations which have a proven record of bad accident history when functioning as at grade junctions.

3) At junctions where the traffic volume is heavy and the delays and loss caused justify economically the grade-

separation is provided.

4) Grade separation to be provided in urban street if the estimated traffic volumes within the next 5 years are in excess of the

capacity of at-grade intersection.

5)

Grade separation to be provided in urban street when traffic projections show that volumes within the next 20 years will

exceed the capacity of at-grade intersection.

6)

Volume to capacity ratio more than 1, grade separation should be provided.

7)

Delay for lane groups, approaches as well as intersection as whole is unaccepted, grade separation should be provided.

8)

LOS for lane groups, approaches and intersection as whole is unaccepted, grade separation should be provided.



Conversation of at Grade Signalized Intersection in to Grade Separated Intersection (IJIRST/ Volume 2 / Issue 05/ 018)


IV. METHODOLOGY FOR ANALYZING SIGNALIZED INTERSECTION

Saturation F low RateA.

Saturation flow rate is a basic parameter used to derive capacity. Saturation flow rate is computed for each of the lane groups.

Saturation flow rate is calculated for prevailing conditions. A default value is selected for base saturation flow rate and it must be

adjusted for a variety of factors that reflect geometric, traffic, and environmental conditions specific to the site under study. The

saturation flow rate is the flow in vehicles per hour that can be accommodated by the lane group assuming that the green phase

were displayed 100 percent of the time (i.e. g/C = 1.0). Saturation flow rate (s) for lane group is estimated by following equation:

Saturation flow rate = (Base saturation flow rate) x (Numbers of lanes) x (Adjustment factors)

Capacity AnalysisB.

The capacity of a given lane group may be stated as shown in equation:

C

gsc

i

ii

Where

ci = capacity of lane group i (veh/h),

si = saturation flow rate for lane group i (veh/h),

gi/C = effective green ratio for lane group i.

C = cycle length (s).

Volume to Capacity Ratio AnalysisC.The ratio of flow rate to capacity (v/c), called the volume to capacity ratio. It is given the symbol X in intersection analysis. It is

typically referred to as degree of saturation for a given lane group i, X i,

i

c

vXi

Where

Xi = (v/c)i = ratio for lane group i,

vi = actual or projected demand flow rate of lane group i (veh/h),

C = cycle length (s).

Cri tical Volume to Capacity RatioD.

This is the v/c ratio for the intersection as a whole, considering only the lane groups that have the highest flow ratio (v/s) for a

given signal phase. Generally one of two lane groups will require more green time than the other (i.e, it will have a higher flowratio). This would be the critical lane group for that signal phase.

LC

C

CiS

V CX

Where

Xc = critical v/c ratio for intersection;

= summation of flow ratios for all critical lane groups i;

C = cycle length (s); and

L = total lost time per cycle, computed as lost time, t L, for critical path of movement (s).

Delay AnalysisE.

The values derived from the delay calculations represent the average control delay. Control delay includes movements at slower

speeds and stops on intersection approaches, such condition occurs when vehicles move up in queue position or slow down

upstream of an intersection. Following equation used for control delay calculation.d = d1 (PF) + d2 + d3

Where,

d = control delay per vehicle (s/veh),

d1 = uniform control delay (s/veh),

PF = progression adjustment factors,

d2 = incremental delay (s/veh),

d3 = initial queue delay, (s/veh).





Aggregated Delay EstimatesF .

The procedure for delay estimation is the control delay per vehicle for each lane group. It is often desirable to aggregate these values to providedelay for an intersection approach and for the intersection as a whole. This aggregation is done by computing weighted averages, where thelane group delays are weighted by the flows in the lane groups.

Approach Delay (d A )G.

dA =

i

ii

v

vd

Where

dA = delay for Approach A (s/veh),

di = delay for lane group i (on Approach A) (s/veh),

vi = flow for lane group i (veh/h)

Intersection Delay (dI)

dI =

A

AA

v

vd

Where

dI = delay per vehicle for intersection (s/veh)

dA = delay for Approach A (s/veh), and

vA = flow for Approach A (veh/h)

Level of Servi ce (LOS)H .Intersection LOS is directly related to the average control delay per vehicle. Once delays have been estimated for each lane group

and aggregated for each approach and the intersection as a whole, following table is consulted, and the appropriate LOS is

determined.Table - 1

LOS Criteria for Signalized Intersections

LOS Control Delay per Vehicle (s/veh)

A < 10

B >10-20

C >20-35

D >35-55

E >55-80

F >80

V.

CASE –

STUDY –

SHIVARANJANI OVER BRIDGE

Shivaranjani intersection peak hour volume is 13421 vehicles. Survey is carried out for 13 hours from morning 9:00 am up to

night 22:00 pm. Geometric detailed is carried out from site for given intersection. Following are the steps for analyzing

intersection for providing over bridge at Shivaranjani in table format.Table - 2

Saturation Flow Rate

EAST APPROACH WEST APPROACH NORTH APPROACH SOUTH APPROACH

Adjusted Factors LT TH RT LT TH RT LT TH RT LT TH RT

Base Saturation 1800 1800 1800 1800 1800 1800 1800 1800 1800 1800 1800 1800

Number of Lanes 1 3 1 1 3 1 1 4 1 1 4 1

Lane Width 0.933 0.889 1.122 0.933 0.889 0.922 0.933 0.933 1.044 0.933 0.933 1.044

Heavy Vehicle 0.982 0.982 0.982 0.979 0.979 0.979 0.991 0.991 0.991 0.989 0.989 0.989

Grade 1 1 1 1 1 1 1 1 1 1 1 1

Parking 0.82 1 1 0.82 1 1 0.82 1 1 0.82 1 1

Bus Blockage 1 1 1 1 1 1 1 1 1 1 1 1

Area Type 1 1 1 1 1 1 1 1 1 1 1 1





Lane Utilization 1 1 1 1 1 1 1 1 1 1 1 1

Left Turn 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95

Right Turn 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85 0.85

Right Turn ped/bike 1 1 1 1 1 1 1 1 1 1 1 1

Left Turn ped/bike 1 1 1 1 1 1 1 1 1 1 1 1

Adjusted Saturation 1092 3807 1601 1089 3795 1312 1102 5378 1504 1100 5365 1501

Table - 3Lane Group Capacity


LT TH RT LT TH RT LT TH RT LT TH RT

V (veh/h) 892 2148 488 1004 2168 416 632 2308 448 600 2336 464

S (veh/h) 1092 3807 1601 1089 3795 1312 1102 5378 1504 1100 5365 1501

t L (s) - 4 4 - 4 4 - 4 4 - 4 4

g (s) - 46 26 - 46 26 - 36 26 - 36 26

g/C 1 0.307 0.173 1 0.307 0.173 1 0.24 0.173 1 0.24 0.173

C (veh/h) 1092 1169 277 1089 1165 227 1102 1291 260 1100 1288 260

Table - 4Lane Group Volume to Capacity Ratio



V (veh/h) 892 2148 488 1004 2168 416 632 2308 448 600 2336 464

C (veh/h) 1092 1169 277 1089 1165 227 1102 1291 260 1100 1288 260

V/C 0.817 1.838 1.762 0.922 1.861 1.833 0.574 1.788 1.723 0.545 1.814 1.785

Table - 5Critical Lane Group per Phase

PHASE – 1 PHASE - 2

EAST WEST NORTH SOUTH

TH RT TH RT TH RT TH RT

V (veh/h) 2148 488 2168 416 2308 448 2336 464

s (veh/s) 3807 1601 3795 1312 5378 1504 5365 1501

v/s 0.564 0.305 0.571 0.317 0.429 0.298 0.435 0.309

Critical lane group/ Phase

(Y) (Y) (Y) (Y)

Table - 6

Critical Flow Rate to Capacity Ratio, Xc,

WEST SOUTH

TH RT TH RT

Critical lane group/Phase (Y) (Y) (Y) (Y)

Sum of critical v/s 1.632

Total Lost Time 16

Critical Flow Rate/Capacity Ratio X C 1.827

Table - 7

Lane Group Delay & LOS Analysis

East Approach West Approach North Approach South Approach


d1 (s/veh) 0 75 75 0 75 75 0 57 62.03 0 57 62.03

K 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50





d2 (s/veh) 6.75 380.42 357.37 14.4 390.72 372.64 2.25 357.72 341.13 2.03 369.39 368.34

d3 (s/veh) 0 0 0 0 0 0 0 0 0 0 0 0

PF 1 1 1 1 1 1 1 1 1 1 1 1

d (s/veh) 6.75 455.42 432.37 14.4 465.72 447.64 2.25 414.72 403.16 2.03 426.39 430.37

LOS A F F A F F A F F A F F

Table - 8Approach Delay with LOS Analysis East and West Approach


Approach Delay 338.79 337.34 340.37 352.69

Approach LOS F F F F

Table - 9Intersection Delay with LOS Analysis


Intersection Delay 342.14

Intersection LOS F

VI. R ESULT ANALYSIS

Following tables show the results for analysis intersection to providing over bridge at Shivaranjani.

Table - 10Capacity and Present Traffic Volume

Approach Capacity (Veh/h) Present Traffic Volume (Veh/h)

North 2653 3230

South 2648 3292

East 2538 3432

West 2481 3467

Intersection Total 10320 13421

Compari son between Volume to Capacity Ratio and F low Conditi on for L ane GroupsA.

There are three different conditions for measuring flow condition.

These are:1)

When v/c ratio less than one, flow condition is under saturated

2) When v/c ratio equal to one, flow condition is saturated

3) When v/c ratio more than one, flow condition is over saturatedTable - 11

v/c Ratio and Flow Condition for Lane Groups

Approach Lane Group v/c Ratio Flow Condition

North

LT 0.574 Under Saturated Flow

TH 1.788 Over Saturated Flow

RT 1.723 Over Saturated Flow

South




East


TH 1.838 Over Saturated Flow RT 1.762 Over Saturated Flow

West




Compari son between Cr iti cal Volume to Capacity Ratio for I ntersection and F low Conditi onB.

There are three different conditions for measuring critical flow.

These are:

1)

When critical v/c ratio for intersection less than one, flow condition is under saturated

2)

When critical v/c ratio for intersection equal to one, flow condition is saturated

3)

When critical v/c ratio for intersection more than one, flow condition is over saturated





There are four lane groups which behave as a critical lane group at Shivaranjani Intersection.

They are:

South approach through lane group

South approach right turn lane group

West approach through lane group

West approach right turn lane groupTable - 12

Critical v/c Ratio for Intersection and Flow Condition

Approach Lane Group Critical v/c Ratio Flow Condition

SouthTH

1.827 Over Saturated Flow

RT

West TH

RT

Table - 13Delay and Level of Service for Lane Group

Approach Lane Group Lane Group Delay (s/veh) Lane Group Level of Service

North

LT 2.25 A

TH 414.72 F

RT 403.16 F

South

LT 2.03 A

TH 426.39 F RT 430.37 F

East

LT 6.75 A

TH 455.42 F

RT 432.37 F

West

LT 14.4 A

TH 465.72 F

RT 1.833 F

Table - 14

Delay and Level of Service for Approach and Intersection

Approach Delay (sec) Level of Service

North 340.37 F

South 352.69 F

East 338.79 F

West 337.34 F

Intersection 342.14 F

VII. CONCLUSION

Conclusion of WorkA.

The present traffic volume of shivaranjani intersection is more than present capacity of intersection. So grade separation to

be provided.

The v/c ratios for lane groups are unacceptable and all turning movements are protective phasing. So geometric changes will

require.

The critical v/c ratio for intersection as whole is greater than one. So intersection geometry changes will require.

The delay for lane groups, approaches and intersection as whole are unacceptable and delay level of service is F.

Hence, to convert the shivaranjani at grade intersection in to grade separated intersection.

R EFERENCES

[1]

Highway Capacity Manual, Transportation Research Board, National Research Council, Washington, D.C., 2000

[2]

Subhash C. Saxena, A Course in Traffic Planning and Design, Dhanpat Rai Publication, Second Edition

[3]

S.K. Khanna and C.E.G. Justo, Highway Engineering, New Chand and Bros, Eight Edition, 2001, Roorkee[4]

C. Jotin Khisty, Transportation Engineering an Introduction, Prentice Hall Englewood Cliffs, 1990, New Jersey

[5]

L.R. Kadiyali, Traffic Engineering And Transport Planning, Khanna Publishers, Sixth Reprint, 2004

[6]

Chhanya Arun R, Adaptive Traffic Control Signal Design for an Isolated Intersection, 2004

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Conversation of at Grade Signalized Intersection in to Grade Separated Intersection