In Toronto, Canada adaptive signal control reduced ramp queues by 14 percent, decreased delay up to 42 percent, and reduced travel time by 6 to 11 percent; and transit signal priority reduced transit delay by 30 to 40 percent and travel time by 2 to 6 percent.
Measurable mobility benefits were reported during the following projects:
Modernization of the City’s Main Traffic Signal System (MTSS)
Toronto embarked on a Communications Reconfiguration Project (the COM Project) designed to reduce traffic control system communications costs by approximately 60 percent to 70 percent. The network wide system reconfiguration involved approximately 1850 signalized intersections connected to approximately 130 specially developed communication multiplexers designed to connect the Main Traffic Signal System (MTSS) and advanced adaptive control systems (SCOOT) with the central computers via high speed circuits.
The reconfigured communication system design pivoted on the application of central computers and software for the multiplexing/demultiplexing logic. This eliminated the requirement of costly annual system maintenance contracts.
Deployment of a SCOOT Signal System in Toronto
SCOOT (Split Cycle Offset Optimization Technique) was an adaptive signal control system that quickly updated signal timings to meet the needs of changing traffic volumes and patterns. This system yielded a number of benefits such as reductions in travel time, number of stops, queuing, fuel consumption, and air pollution emissions.
Toronto conducted a demonstration project to compare SCOOT to fixed (i.e., predetermined) signal timing control plans. The results were summarized as follows:
- Traffic Flow Speeds--Increased 3 to 16 percent.
- Left Turn Violations--Reduced 71 percent.
- Rear-end Conflicts--Reduced 24 percent.
- Ramp Queues--Reduced 14 percent.
- Intersection Stop--Reduced 18 to 29 percent.
- Intersection Delays--Reduced 10 to 42 percent.
- Left Turn Delays--Reduced 0 to 35 percent.
- Vehicle Delay--Reduced 6 to 26 percent.
- Vehicle Stops--Reduced 10 to 31 percent.
- Vehicle Travel Time--Reduced 6 to 11 percent.
- Pollution Emissions--Reduced 3 to 6 percent.
- Fuel Consumption--Reduced 4 to 7 percent.
Based on the positive results of SCOOT, Toronto expanded the system to control approximately 250 additional signalized intersections. The payback period for the expansion project was estimated at less than two years.
Development of a Signal Priority System for Streetcars
In 1991 the Toronto Transit Commission (TTC) and the Ministry of Transportation of Ontario (MTO) completed a Traffic Signal Priority Demonstration Project designed to assess "traffic signal priority" systems for streetcars operating in mixed traffic. This system was designed to detect and give signal priority exclusively to streetcars at six intersections in Toronto. The streetcars were detected by means of an on-board transmitter and a receiver antenna embedded in pavement at the intersection. The streetcar was given priority by pre-empting the pre-programmed signal timing of the local signal controller otherwise governed by the MTSS central computer system. The result was an extension of the main-street green or a truncation of the cross street green depending on the position in the signal cycle when a streetcar was detected. The priority request was then cancelled once the streetcar passed over the intersection stop bar antenna. The central computer then resumed control of the signal timing and coordination with adjacent intersections.
The study found that total streetcar delay was reduced by 35 percent and there were no significant impacts on side street queue delays.
Development of a Signal Priority System for Buses
Following the completion of the demonstration project for streetcars another project was initiated in 1995 to determine the applicability of these newly tested strategies on bus priority. The bus priority system was employed on a major suburban arterial with ten signalized intersections. Four of the intersections had cross-street transit service.
The demonstration used infrared technology to transmit the detection signal from the bus to a wayside receiver. A radio transmission was broadcast to link the signal to the intersection controller. This design allowed for a selective detection of buses without the need for in-pavement inductive loops or wire feeders. The operation of the transit priority system was similar to that described for streetcars.
Detailed surveys were conducted during AM peak periods, midday periods, and PM peak periods with and without signal priority. Transit signal priority provided the following benefits:
- In the AM peak period, round trip transit travel time was reduced by 34 seconds (2 percent).
- In the midday period, round trip transit travel time was reduced by 84 seconds (6 percent).
- In the PM peak period, round trip transit travel time was reduced by 69 seconds (4 percent).
- In the AM peak period, round trip transit signal delay was reduced by 61 seconds (30 percent).
- In the mid-day period, round trip transit signal delay was reduced by 74 seconds (40 percent).
- In the PM peak period, round trip transit signal delay was reduced by 79 seconds (37 percent).
ITS Technology Meeting Municipal Needs - The Toronto Experience
Author: Greenough and Kelman
Published By: Paper presented at the 6th World Congress Conference on ITS. Toronto, Canada
Source Date: 8-12 November 1999
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bus priority, traffic signals, TSP, adaptive signals