design of vehicle actuated signal for a major...
TRANSCRIPT
DESIGN OF VEHICLE ACTUATED SIGNAL FOR A
MAJOR CORRIDOR IN CHENNAI USING SIMULATION
Authors
S.NITHYA R.NITHYANANTHAN D.SENTHURKUMAR K.GUNASEKARAN
Presented by,
R.NITHYANANTHAN S. KALAANIDHI
Introduction
Most of the cities in India have fixed time signal settings and it is operated manually during morning and evening peak hours.
Manual operation is adopted assuming that the traffic police personnel would judge the length of queue in each arm and would apportion green time for vehicles to clear the intersection based on queue length.
Manual control does not offer considerable benefits in reducing the delays of all vehicles.
Vehicle actuated (VA) equipped with Virtual Loop detectors and the necessary control logic to respond to the demand placed on traffic movements to be serviced.
Benefits of Vehicle Actuated Signals
• Handle the random fluctuations in the traffic condition
• Works on the real time information
• Vehicle presence is conveyed to the controller through the detectors placed for the various movements
• Reduce the overall delays and optimizes the signal timings at the intersection
• Especially effective at multiple phase intersections.
Need for Vehicle Actuated Signals
When demand varies
significantly from time to
time, either green time is
wasted or queue forms.
To avoids these variation
in arrival vehicle actuated
signal are necessary
Wasted green Queue forming
Vehicle actuated signals with varying phase time which
automatically varies the phase time helps in improving the
intersection function
Real Time Detection of Traffic
• Video cameras with virtual
loop detectors are able to
detect the presence of
vehicles.
• This virtual loop is used to
place at nearby intersection
and also for advance
detection.
• Multiple detection zones per
lane possible to cover a
larger area
Narrow Angle Wide Angle
ADVANCE DETECTION
STOP BAR DETECTION
Length of Detection Zone
depends on Permitted speed
Vehicle Actuated Signals
Actuated Control may be programmed to accommodate
• Variable Phase Sequence
• Variable Green time for each phases
• Variable cycle length, caused by variable green time
The cycle length, phase splits, even the phase sequence may vary from cycle to cycle.
Semi-actuated control
Detection only on minor side-street approaches; green remain on the main until a “call” for service on the side street is registered.
Full-actuated control All approaches have detectors; equal importance of the direction of traffic; for relatively isolated intersections;
Volume-density control
Basically functions like full-actuated control; good for high-speed approaches (>= 45 mph); Has extra features to adjust initial timing and reduce the gap extension during green extension time
Actuated control and controllers
Detection type
Point detection (“passage” type)
A single detector is placed for each approach lane to be actuated.
The detector relays information as to whether a vehicle has passed over the detector.
Area detection (“presence” type)
Generally used in conjunction with volume-density controllers.
The importance is placed on the existence of a vehicle (s) in the detection area.
They “count” the number of vehicles stored in the detection area.
Actuated control features and operation
Minimum green time
(Initial green + unit
extension)
Passage time interval
Maximum green time
Recall switch (unless
the subsequent phase
has the recall “on” green
remains to the previous
phase unless demand
exists)
Yellow and all red
Simulation Model Building
Model Building The processes and steps involved
Step 1 : Sections on the road network,
Step 2 : Vehicle types and classes were used to define the vehicle parameters.
Step 3 : Speed distributions defined from observed data.
Step 4 : Traffic compositions created for entry points to the network.
Step 5 : Placement of routing decision points in the network.
Step 6 : Placement of signal positions and signal timing in the road network.
Anna Salai, major arterial road in Chennai city, a stretch of 3.1 km was selected as
study stretch. With the development of educational institutions, commercial activities the
corridor have encountered problems such as traffic congestion, road accidents, and also
air pollution.
STUDY AREA
Intersection volume in vehicle/hour
S.No Intersection
Volume in
vehicles/hour
1 Thiruveka Junction 8883
2 Smith Road Junction 7086
3 Spencer Junction 12344
4 Wellington Plaza Junction 7881
5 Walajah Road Junction 11624
Video graphic survey at Spencer
intersection
Two video Cameras were installed on a tall building at Spencer
intersection to measure the volume and queue length in the morning from
7.00A.M to 12.00P.M
The survey was conducted during morning peak hour and evening peak hour.
The GPS instrument was used to measure the travel time and delay for the
entire stretch.
.
Travel Time along Study Corridor
•The travel time on Mount
Road from (Thiruveka junction
to Walajah junction) was
around 110 seconds in peak
hours and around 87 seconds
when travelling in opposite
direction
Study Stretch
Morning Peak Hour
(km/hr)
Thiruveka to LIC 24.504
LIC to Thiruveka 23.281
Travel Pattern in the Study Stretch The travel pattern has been arrived from the turning movements data. Totally 12
movements were considered. The in–out traffic is given in the form of O-D Matrix
1 1
2
3
4 5 6
8
7 9
10
11
12
OD projection for the study stretch
1 2 3 4 5 6 7 8 9 10 11 12 Total
1 - - 124 - - - 1784 - 710 948 - 948 4514
2 394 - 389 - 83 - 104 - 43 10 - 6 1029
3 - - - - - - - - - - - - 0
4 320 - 100 - 20 - 59 - 19 8 - 14 540
5 - - - - - - - - - - - - 0
6 188 - 40 - 12 - 228 - - - - - 468
7 926 - 342 - 64 - - - 190 240 - 456 2218
8 242 - 23 - 149 34 82 - 380 149 - 384 1443
9 - - - - - - - - - - - - 0
10 664 - 139 - 169 69 289 - 84 - - 2181 3595
11 742 - 84 - 174 - 149 - 24 1202 - 243 2618
12 1038 - 849 - 362 389 492 - 194 977 - - 4301
Total 4514 0 2090 0 1033 492 3187 0 1644 3534 0 4232 20726
The scenarios were formulated to study the performance of the
study stretch and to identify the best option.
Scenario1: Existing Condition with fixed time signal
Scenario 2: Vehicle actuated Programming
Scenario 3: Co ordinate fixed time signal
SCENARIO FORMULATION
Model Validation
The validated model was within the tolerance of the validation criteria (10%).
To validate the model correctly comparisons were made exiting volume with the observed volume
Ju
ncti
on
Street Vehicle Movement
Number of Vehicles / hour
Simulated Condition Existing Condition
Sp
en
cer J
un
cti
on
Gemini Road
Left 647 784
Through 2499 2517
Total 3146 3301
EA Road
Left 311 328
Right 246 249
Total 557 577
Benny Road
Left 276 295
Right 3186 3926
Total 3462 4221
LIC Road
Left 100 94
Through 4104 4207
Right 456 538
Total 4660 4839
Total 11825 12938
Scenario 1 gives the existing condition of study area. . Fixed time signal settings preferred for
morning peak hour was used.
Behavior of Scenario 1 – Existing Condition
Scenario 2 gives the corridor performance with vehicle actuated signals
Variable cycle time / variable phase timing model was attempted for the intersections.
Behavior of Scenario 2 – Vehicle Actuated Signal
Defining vehicle detection zone by placing the two detectors for each lane in each approach.
The detectors sensed the presence/absence of vehicles in between them.
Cond.,
Towards Gemini Detector Exit
Detector Entry
Towards LIC
Thiruveka
Junction
Function of VAP
The cycle time of critical intersection was adopted for all intersections and co – ordination for
movement of vehicles towards Parrys was attempted.
The offset timing for the signals assuming vehicle speed of 30km/hr was considered for co
ordination.
Behavior of Scenario 3 – co ordinate signal
Comparison of VA with fixed timings
RESULTS AND DISCUSSIONS
The individual intersection
performance shows significant
reduction in delay to about 28% if
vehicle actuated signals are
adopted.
The reduction in intersection
delay for scenario 2 was from
20% to 39% when compared
with scenario 1.
At the critical intersection i.e.,
Spencer intersection the delay
reduction was 39%.
Comparison of Fixed time signals with coordinated fixed timing signals
RESULTS AND DISCUSSIONS
The cycle time of the signals
was assumed to be 140seconds,
i.e., the cycle time required for
critical intersection.
The speed of the traffic flow
was assumed as 30kmph.
On Co-ordination of signals an
average 8% reduction in delay is
possible when compared to
scenario 1.
Similarly if Co-ordination of
Vehicle actuated signals is
attempted, reduction in delay
could be realised.
Vehicle actuated signals is proposed to replace the existing fixed
time signals.
With implementation of Vehicle actuated signals 28% delay
reduction is possible.
Further reduction is possible if a Co-ordination of Vehicle actuated
signal is attempted.
With the development in technology like Virtual loop Camera it is
possible to erect Vehicle actuated signals.
CONCLUSIONS
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