Traffic Control Signals
There are two types of signal operations: Fixed-Time signals and Semi-Actuated signals.
Fixed-Time signals are normally installed at the intersection of two major roads (ie Yonge Street and Dundas Street). Fixed time signals constantly cycle in sequential order and do not depend on any type of detections such as pedestrian push-buttons. All roads and movements are served in a constant specific order.
Semi-Actuated signals are typically installed at the intersection of a major road and minor road (ie. McCowan Road and Brimorton Drive). In these cases, the signals remain green on the major road (McCowan Road) until a vehicle or pedestrian is detected on the minor road (Brimorton Drive). Vehicles on the minor road are detected by electromagnetic wires (loops), which are imbedded in the pavement on the side street near the stop bar.
Pedestrians are detected by the pedestrian pushbuttons. This tells the traffic signal to change to green for the minor road and gives pedestrians sufficient time to cross the main road (McCowan Road) and/or receive a pedestrian signal display.
Here are some common misconceptions motorists have at semi-actuated traffic control signals:
If I back up and drive forward again, the signal change quicker - This does not work. The detector mechanism does not count the number of vehicles waiting.
If I get out of my car and push the pedestrian button, the green light comes on quicker – If the traffic control signals are functioning properly, the pedestrian push-button does not make the green indication appear sooner. However, it can make the green light longer at some semi-actuated signals since it takes longer for a person to walk across a street than it takes for a car to drive across a street.
Pedestrian push buttons are not provided at busy intersections ((ie Yonge Street and Dundas Street) since signal displays change from street to street all day long. However, at a major road/minor road intersection (ie. McCowan Road and Brimorton Drive), the side street will not change to green until a vehicle is detected or a pedestrian presses the button.
This situation occurs when a vehicle has been detected on the side-street and no pedestrian has pushed the button. This only can occur at locations where the City’s Transportation Staff has installed a Semi-Actuated “Type 2” (SA2) intersection. With this type of operation, a pedestrian must push one of the pedestrian push buttons to receive a "Walk" signal. When a button is pushed, a pedestrian will receive a "Walk" signal with sufficient time to cross the major road. If a button is not pressed and the traffic control signals respond to a vehicle only, a green signal will be displayed along with a "Don't Walk" indication for pedestrians. The length of this green signal could be considerably shorter than the required walk time for a pedestrian because the length of the green signal is variable, based on the vehicle demand only (as the pedestrian push button was not pressed).
We use this type of operation to maximize the efficiency of the intersection. It serves to minimize delay for the relatively heavier volume of traffic on the major road.
It is the City’s practice to always install pedestrian information signs, which describe this operation at these types of intersections.
Some pedestrians misunderstand the “Flashing Don’t Walk” or "Helping Hand" display feature. This feature is intended to warn pedestrians who have not started to cross that there is not enough walk time left to start and complete their crossing safely. If they have started to cross and the "Helping Hand" indication appears, there is still sufficient time to complete their crossing. The duration of the "Helping Hand" indication is included in the calculation of the pedestrian walk time. Where this feature is installed, it is augmented with information signs to explain the operation.
Pedestrian walk times are calculated based on the walking speed of a typical adult (1.2 metres per second). At locations with high percentages of senior citizens or children, walk speeds are reduced to 1.0 metres per second to accommodate a slower walking speed.
If left-turn volumes are low and motorists are not experiencing significant cycle delays, it is expected that motorists will turn on the amber. During the all red phase, all signal heads are showing red and all traffic is stopped. Vehicles are not allowed to proceed through the intersection until the all red signal is over. This gives left-turning motorists the opportunity to legally clear the intersection in safety before the other directions begin to move. Generally, the all red phase is two to three seconds in duration dependent on the width of the intersection.
Left-turn advance features can be programmed to operate during specific periods of the day. Where warranted, these features are typically programmed to operate during the morning and afternoon peak periods, when left turn demand is highest.
Left-turning vehicles are detected by “detector loops,” which are embedded in the pavement at either the stopbar or at a distance of approximately three car lengths back from the stopbar in the left-turn lane. At locations where the latter is in place, only the third vehicle in a left-turn queue will activate the left-turn priority feature. This type of operation serves to maximize the efficiency of the intersection. We assume that two vehicles will normally safely clear the intersection during the amber display.
The development of signal timing is a “balancing act” where the City tries to allocate movement fairly to all directions. In some cases, the City would prefer a longer left-turn priority feature but often is constrained by high traffic volumes arriving at the intersection from other directions. For instance, if we add more time onto a left-turn priority feature we must remove “green” time from other traffic movements.
The traffic signals on city arterial roadways are generally synchronized or co-ordinated to minimize stops and delays on the arterial roadways. In other words, the City tries to provide a smooth movement of the traffic through groups of signals on an arterial street. The degree or quality of traffic signal co-ordination is influenced by a number of factors including such things as the spacing of the signals along the street, the prevailing speed of traffic on the street, and the traffic signal cycle length.
The goal of signal co-ordination is to get the greatest number of vehicles through the system with the fewest stops in a comfortable manner. It would be ideal if every vehicle entering the system could proceed through the system without stopping. This is not possible, even in well-spaced, well-designed systems. Therefore, in traffic co-ordination, the majority rules, and the busiest traffic movements are given precedence over the smaller traffic movements.
Many drivers, who wait to enter a major street from a side street, often ask why they have to wait so long for a signal to change, especially when no traffic can be seen on the larger street. To allow for co-ordination on the larger street, the side street traffic must wait until the main traffic movement on the larger street has gone through the intersection. It is possible that the traffic on the larger street can’t be seen immediately, but will soon be passing through the intersection.
A total of 83% of our signals are controlled by a central computer, which is called the Main Traffic Signal System (MTSS). MTSS provides different timing plans for different times of day and allows Transportation staff to monitor its operation.
More than 15% of our signals are on the SCOOT system. SCOOT (Split, Cycle and Offset Optimization Technique) is a demand-responsive Urban Traffic Control system. The system uses “loop vehicle detectors” located on all approaches to the intersection. The data produced by these detectors are processed by a central co-ordinating computer, which may decide to alter the traffic signals at an intersection. One of the features of SCOOT is that signal timings are changed frequently (typically every phase or cycle) and gradually (usually by only a few seconds at a time).
Other Traffic Control Devices
To determine whether the installation of an all-way stop is warranted, Transportation staff must first conduct a traffic study at the intersection. This study considers a number of key factors such as collisions, traffic volumes, roadway geometry and neighbouring traffic control devices. If the requirements are met, staff will typically recommend the installation of an all-way stop. Then, the local Community Council must approve the installation.
All-way stop controls operate more effectively at intersections with higher traffic volumes, and a balanced split between the traffic on the major street and on the minor street.
All-way stops are intended to control right-of-way and are not intended as speed control devices.
Before the city considers implementing a 40 km/h speed zone on a given street(s), within a community, Transportation Services staff first conducts a speed study to determine the volume of traffic on the street as well as the prevailing vehicle speeds. The study looks at a number of factors including operating speed, collisions, roadway geometry, adjacent land uses and pedestrian activity. If the requirements are met, staff will typically recommend the change which must then be approved by the local Community Council.
40 km/h speed limits are typically posted on local and collector roads in front of schools, or if the road is constructed in such as way that would require motorists to reduce their speed.
Parking in front of most schools can be chaotic during school admission and dismissal. Transportation Services staff work with staff from the school, the Toronto Police Service and concerned parents to improve this situation through education, enforcement or adjustment to the parking regulations. There are also a number of innovative programs available to assist with traffic management in the vicinity of schools. Transportation Services staff will investigate the concerns of residents and/or school staff to determine what is the best way to improve the situation at the school.
Traffic calming is a term most commonly associated with physical features placed on a roadway to influence the speed of vehicles. The most common form of traffic calming in the City of Toronto is the speed hump.
There are many factors to be considered before traffic calming devices are installed. One of the most important factors is the support of the residents living on the street where the traffic calming is being proposed. A petition showing support of residents on the street is the first step toward having a traffic calming device installed in a neighbourhood.
Traffic calming measures such as speed humps can have a positive influence in reducing vehicle speeds. However, there are negative effects associated with traffic calming including, increased noise, decreased emergency vehicle response times, increased air pollution and diversion of traffic to adjoining streets.