GREEN TRAFF
C SOFTWARE
Software decongesting cities
Location: Tsaritsa Ioanna Blvd - Todor Aleksandrov Blvd, Sofia, Bulgaria
Number of intersections: 15
This case study is an example of Green Traffic Software tool applied to a real urban city arterial. Here we are dealing with one of the busiest arterials in the city, connecting its north-west district with the center. A part of it (9 intersections) is already coordinated though not in an optimal way while the entire arterial is not.
GTS provides multiple coordination schemes for both the part and all 15 intersections together. What is special about this arterial is that the maximal sum bandwidth is the same (55 s) in both cases. It exceeds the current sum bandwidth (46 s).
Maps data: Google, © 2023
Input arterial data:
Number of traffic lights
Distances between them
Recommended vehicle velocity
Split phasing
Cycle lengths and the desired common cycle length
Yellow rectangles in the table and on the map highlight the coordinated part of the arterial.
Data source: Dom Eleshnitsa LtD
Current timing plan by the local Intelligent Transport System:
9 intersections, sum bandwidth 46 s:
The subset of 9 intersections, from 6 to 14, is coordinated, while the entire arterial is not. The time-space diagram of the coordinated subset shows that currently the sum bandwidth is 16 + 30 = 46 s.
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With GTS, these 9 intersections can be coordinated in a better way, see below.
GTS, 9 intersections, sum bandwidth 55 s:
GTS provides the arterial portrait, showing all possible pairs of bandwidths with 1 sec resolution. In total, 1244 bidirectional timing plans are available, 24 of them provide the maximal sum bandwidth of 55 seconds.
Each green asterisk leads to a particular timing plan: offsets and phase sequences ("orders") are shown together with the time-space diagram. The dark green asterisks mark the bandwidths pairs with maximal sum. The blue circles mark the bandwidth pairs that are impossible in this arterial.
Two TSDs below correspond to the bandwidth pairs marked with green squares. Brown square marks the current coordination scheme.
Inbound bandwidth: 17 seconds
Outbound bandwidth: 38 seconds
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Inbound bandwidth: 40 seconds
Outbound bandwidth: 15 seconds
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Now let us turn to the entire arterial. Currently, it is not coordinated at all but the problem can be easily solved with the use of GTS.
GTS, 15 intersections:
For the given cycle length of 110 s we get an arterial portrait containing 19 different timing plans with sum bandwidth 46 s:
We get even better solutions by changing the cycle length. Specifically, at C = 108 s the number of available timing plans decreases to 8 but the sum bandwidth becomes the same as that for 9 intersections subset: 55 s.
Two timing plans below correspond to the bandwidth pairs marked with green squares.
Inbound bandwidth: 18 seconds
Outbound bandwidth: 37 seconds
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Inbound bandwidth: 25 seconds
Outbound bandwidth: 30 seconds
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This study proves that the widespread belief of coordination deterioration with the number of intersection increasing is not always true (read more here).