International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 8- May 2015
Design & Coordination of Traffic Signals of Two
Adjacent Roundabouts of Chandigarh
Ravi Arora1, Dr P.K. Gupta2
ME Research Scholar,1Associate Professor2
PEC University of Technology Chandigarh
Abstract—Rapid urbanisation and industrialisation has led to
substantial increase in urban traffic. Thus congestion on urban
road is a common phenomenon in cities. India is also facing the
problem. Chandigarh, a Union Territory of India was planned
by Le Corbusier’s and the city also known for its beautiful
roundabouts. But these roundabouts become place of slow
moving traffic during peak hours. Thus there is a need to use
traffic management techniques like coordination of traffic to not
only avoid congestion at these roundabouts but also reduce
traffic delay caused to traffic.
Keywords—
Chandigarh,
Roundabouts, Urbanisation.
Congestion,
Coordination,
I. INTRODUCTION
Piccadily Chowk and Kisan Bhavan Chowk are two busy
roundabouts of Chandigarh. Both of these roundabouts are
located on Dakshin Marg. Piccadily Chowk has large volume
of traffic throughout the day as it located between two major
shopping hubs of the town i.e. Sector-17 and Sector-35.Also
all the interstate buses going to or from ISBT 17 have also to
cross this intersection. Kisan Bhavan Chowk being also an
important intersection as all interstate buses turn towards
sector-17 from this intersection and is located between sector36,sector-22,sector-35;all of which are major activity centres.
Thus, heavy traffic flow occurs at these intersection
especially during the peak hours. This heavy traffic leads to
congestion at both these intersections and also the flow of
traffic is not smooth between these two intersections. Thus
synchronisation traffic signal design will help to reduce
congestion on these intersections and increase the efficiency
of these roundabouts. Also co-ordination of the two signals
will help to reduce lost man-hours of road users.
II. OBJECTIVES AND METHODOLOGY
A. Objective of the Study
To design signalised intersection for Piccadily Chowk
and adjoining Kisan Bhavan Chowk using Webster
method.
To co-ordinate the traffic flow between the above two
roundabouts.
B. Methodology used:
Pilot survey: A Pilot survey on study area was done to
study the various road network in the area and to
understand the existing conditions on the road.
ISSN: 2231-5381
Selection of critical points: The critical points are
selected from the study area which are of best interest.
Data collection: The data collection include various
traffic studies pertaining to volume study and speed
study.
Traffic Volume Study: The volume studies and counts
are done on the critical points using videography
method and data collection sheet is prepared.
Speed Studies: Spot speed studies are conducted using
Radar Gun...
Data Analysis: The data collected are then analyzed
for studying speed variation, peak hour flows.
Data collected is used to design signals through
Webster method.
Coordination of signals is done by providing offset.
Conclusions on basis of results obtained.
III. DATA COLLECTED
A. Traffic Volume Study
Traffic volume study was conducted on both these
roundabouts and peak hour data was found for both these
studies
Fig. 1 : Traffic volume at Piccadily Chowk (in PCU‟s)
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 8- May 2015
Total flow „q‟=1630 PCU/hr
Saturation Flow for straight ahead flow
= 525*w =
525*(12.3) = 6458 PCU/hr
2) Phase II Sec-35 Side Straight Ahead Traffic & Sec-17
Side Straight Ahead Traffic
Width of Approach lane (Sec-35 side), w = 9.4 m
Total flow „q‟=1666 PCU/hr
Saturation Flow for straight ahead flow = 525 * w =
525*(9.4) = 4935 PCU/hr
Fig. 2: Traffic volume at Kisan Bhavan Chowk (in PCU‟s)
B. Spot Speed Study
Radar Gun was to find the spot speed of different vehicle
types. Study was conducted mid-way between these two
roundabouts.
Width of Approach lane (Sec-17 side), w = 9.8 m
Total flow „q‟=1671 PCU/hr
Saturation Flow for straight ahead flow= 525*w = 525*(9.8)
= 5145 PCU/hr
Calculation of “Y” Values
Inter-green Period “I” =10 seconds
Amber Period “a”=2 seconds
Time lost due to starting delay “l”=2 seconds/phase
Number of phases =2
Lost time “L”
20seconds
==∑(I-a) + ∑l==2x (10 – 2) + 2 x 2 =
Maximum Value of “Y”
Y1
=
0.3746 (for phase 1)
Y2
=
0.4909 (for phase 2)
Y
=
Y1 + Y 2
=
0.7471
Optimum Cycle length
Fig. 3: Graph of Speed distribution VS Cumulative frequency
AVERAGE SPEED =46.97~47 KM/HR
IV. CALCULATIONS
Traffic Signal were designed at both these intersections
using Webster method. Traffic signal at both roundabout were
kept two phase.
In each phase of the traffic signal, opposing traffic were
incorporated. Inter-green period of 10 seconds was provided.
Amber period and start delay were both considered to be 2
seconds.
A. Design of traffic signal for Piccadily Chowk
1) Phase I-Ambala Side Straight Ahead Traffic & Kisan
Bhavan Side Straight Ahead Traffic
Width of Approach lane (Ambala Side), w = 10.7 m
Total flow „q‟=2147 PCU/hr
Saturation Flow for straight ahead flow „S‟ = 525 * w=
525*15= 7875 PCU/hr
= 138.39 seconds
Effective Green time
CO – L = 138.39 - 20= 118.39 seconds
For Phase I
=
52.53
~
53
seconds
66
seconds
For Phase II
=
65.85
~
Hence,
G1
G2
New Cycle Length
=
=
=
=
=
53 seconds
66 seconds
G1 + G 2 + L
53+66+20
139 seconds
Width of Approach lane (Kisan Bhavan Side), w = 12.3 m
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 8- May 2015
B. Design of traffic signal for Kisan Bhavan Chowk
1) Phase I Piccadily Chowk Straight Ahead Traffic &
Dhanas Side Straight Ahead Traffic
Width of Approach lane (Ambala Side), w = 12.47 m
Total flow, „q‟=1952 PCU/hr
Saturation Flow for straight ahead flow, ‟S‟=525 * w
= 525*(12.47) = 6547 PCU/hr
Width of Approach lane (Kisan Bhavan Side), w = 10.55 m
Total flow, „q‟=1577 PCU/hr
Saturation Flow for straight ahead flow, ‟S‟ = 525*w =
525*(10.55) = 5539 PCU/hr
2) Phase II Sec-35 Side Straight Ahead Traffic & Sec-17
Side Straight Ahead Traffic
Width of Approach lane (Sec-35 side), w = 9.3 m
Total flow, „q‟=1428 PCU/hr
Saturation Flow for straight ahead flow= 525 * w
= 525*(9.3) = 4883 PCU/hr
Width of Approach lane (Sec-17 side), w = 8.2 m
Total flow, „q‟=1889 PCU/hr
Saturation Flow for straight ahead flow‟s‟ = 525*w
= 525*(8.2) = 4305 PCU/hr
Calculation of “Y” Values
Inter-green Period “I”= 10 seconds
Amber Period “a” =2 seconds
Time lost due to starting delay “l” =2 seconds/phase
Number of phases=2
Lost time “L” =∑(I-a) + ∑l
Fig.4: Google Map image of the study area
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 8- May 2015
=2x (10 – 2) + 2 x 2=20 seconds
Maximum Value of “Y”(Y=q/S)
Y1
=
Y2
=
Y
=
=
Optimum Cycle length
References
[1]
0.3746
0.4909
Y1 + Y2
0.8655
[2]
[3]
[4]
Co= (1.5L+5)/ (1-Y)
= (1.5 ×20 +5)/ (1- 0.8655) = 260.22 seconds
Effective Green time
Co– L
= 260.22 – 20 = 240.22 seconds
For Phase I
[5]
[6]
= 103.97 ~104 seconds
For Phase II
[7]
= 136.24 ~ 137 seconds
[8]
Hence,
G1
G2
New Cycle Length
=104+137+20
=
261 seconds
=
=
=
104 seconds
137 seconds
G1 + G2 + L
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C. Determining Offset
Distance between two roundabouts, S=900 metres
Average Speed, V =47 km/hr
Average time taken=S/V=0.9/47=0.0191hr=68.93~ 69 s
V. RESULTS
Cycle time of Piccadily Chownk =139 s
Cycle time of Kisan Bhavan Chowk=261s
Calculated Offset =69s
VI. CONCLUSIONS
1) We should provide cycle time of 139 s to both the
roundabouts as 261 s is very large cycle time.
2) Offset of 69 s will be should to both roundabouts.
3) It would be less time consuming for road users to cross
these roundabouts, when moving from one roundabout to
another.
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