Understanding Traffic Lights

Last updated November 27, 2022
Reading time: 1 min

Everyone knows about red, yellow and green traffic lights, but what about other types of traffic signals?  Do you know exactly what to do at an intersection?  Priorities, sound and light signals, coordination… Our videos help you behave right on the roads.

The City of Montreal has 2,300 intersections with traffic lights.  Red-yellow-green traffic lights are the best known of all, but there are others that are worth discovering.

These educational, entertaining videos were created to shed more light on traffic lights.   They will help you understand how traffic lights improve the flow of motorists, pedestrians and cyclists, as well as firefighters, bus drivers and the visually impaired.  Turn up the lights on traffic lights, here we go!

Countdown pedestrian lights

When approaching an intersection equipped with traffic lights, a few simple steps will help you cross in complete safety:

  1. Check for the presence or absence of “do not cross” signs
  2. Check for the presence or absence of pedestrian crossing lights: if there are none, obey the vehicle traffic lights
  3. Check for the presence or absence of pushbuttons:
    - If there are buttons, press the button for the direction you wish to cross and wait for the “walk” silhouette before beginning to cross
    - If there are no buttons, wait for the “walk” silhouette before beginning to cross
  4. If there are pedestrian lights, start crossing when the silhouette appears and ignore the green lights for vehicles
  5. If there are no pedestrian lights, start crossing as soon as the green vehicle lights appear
  6. Before beginning to cross, look all around to be sure no vehicle is approaching your path.
  • The digital countdown indicates how much time is left to cross
  • “Faster” pedestrians can begin to cross during the countdown, but should make sure they have enough time to cross the intersection
  • A fixed (lit) hand with a green light indicates you must not cross
  • A “walk” silhouette with a red light means you can cross
  • The silhouette is not a protection but signals a permitted action (time for the pedestrians to enter the intersection).   Vehicles may turn at the same time
  • Pedestrians have priority, but you must remain vigilant because you have to share the road.

The time allowed to cross (numerical countdown) is based on the distance to be crossed. Based on several criteria, including the number of vehicular conflicts with the pedestrian crossing, the crossing can be unprotected, partially protected or fully protected:

  • Unprotected: the silhouette lights up at the same time as the green light for vehicles
  • Partially protected: the partially protected crosswalk can have two types of protection: arrow advance or red advance. In both cases, for a short period of time, the silhouette lights up with no conflict between vehicles and the pedestrian crosswalk.  Shortly thereafter, the vehicle green light or the green right arrow will light up
  • Fully protected: Throughout the crossing period (lit silhouette followed by the flashing hand) there will be no conflict with vehicles crossing.

In the coming years, the city plans to install pedestrian countdown lights at all intersections with traffic lights, for every pedestrian crossing (except in cases of unusual sidewalk configurations, crossing prohibited, etc.)

Bicycle lights

Bicycle lights are devices installed at the intersection of a bike path and a public road to indicate to cyclists when to cross. In combination with traffic signals, they help control cyclists’ movements and avoid conflicts with other vehicles and pedestrians.

What should a cyclist do when approaching an intersection equipped with traffic lights?

  1. Check for the presence or absence of “do not cross” signs
  2. If bicycle lights are present, cyclists should use only these lights. They must not use pedestrian or vehicular traffic lights
  3. If there are no bicycle lights, cyclists may follow the pedestrian or vehicular traffic lights
  4. If signs indicate an obligation to use the pedestrian lights, then cyclists must follow the pedestrian lights and not the vehicular lights.
  5. In the absence of these signs, it is permitted to cross on an active pedestrian light. Take note that cyclists must first come to a complete stop and ensure that they can continue on their way without danger. At all times, priority must be given to pedestrians (cyclists must let pedestrians pass through the intersection)
  6. However, cyclists may not cross on an active pedestrian crossing signal if a sign prohibits this. In this case, the cyclist must follow the vehicle traffic lights.

When a cyclist rides on a bicycle path or lane, he or she has two possibilities for making a left turn:

  1. The cyclist leaves the bike lane and enters the left turn lane with other vehicles
  2. The cyclist stays in the bike lane and carries out an “L” turn in two steps. Cyclists must not cross diagonally.

It is important for cyclists to stop at the stop lines at intersections, as there may be traffic detectors in operation.

Sound signals

Audible signals allow the blind and visually impaired to orient themselves and to cross the intersection, clearly identify the appropriate time to begin crossing, and maintain a straight path through the intersection. Sound signals are installed only for the blind and visually impaired.

They are emitted by loudspeakers added to pedestrian crossing lights. They are activated by a call button linked to a nearby loudspeaker that emits one click tone per second to help in locating the button. The sound is adjusted depending on the ambient noise. When the sound signals are active, the crossing is fully protected, that is to say, there is no conflict with road vehicles.

Orientation and mobility specialists from a rehabilitation centre for visual disabilities must make an assessment in order to decide whether adding sound signals to existing pedestrian signals is well-founded. This goal of this assessment is to establish the pertinence of a pedestrian facility based on the needs of the requesting person with a visual disability, the design of the intersection and the possible alternate routes.

Once a request to add sound signals has been received, an analysis must also be made by a city traffic engineer to evaluate the feasibility of adding the sound signals to the traffic lights while ensuring the safety of all users.

Coordination of traffic signals

Detection at traffic signals

Special measures for buses

Special measures for buses (SMB) allow buses to modify the normal operations of traffic lights when possible, to better accommodate them.

The Société de transport de Montréal (STM) has made recommendations about various SMB measures that will improve service for public transit users.

  1. Reserved lanes for buses
  2. Priority lights for buses (candle lights)
  3. Advanced transit signal priority (TSP) systems 

TSP is engaged when buses are behind schedule. It helps buses keep on schedule.

  • “Queue jump” (white band): until recently, bus light phases were memorized but, with TSP, these phases will be activated only when buses are present.
  • Green extension: when buses are present, the extension allows a predetermined phase to last some seconds longer (more green time), to let a bus pass that would otherwise have arrived a few seconds too late and had to wait through a red light.
  • Red truncation (also called Early green): when a bus is present, red truncation allows a predetermined light phase to end a few seconds early, letting the bus phase begin a few seconds earlier. This allows a bus that would otherwise have arrived a few seconds too early for the green light to avoid stopping and waiting.
  • Vertical white band: allows buses only to go straight ahead, in order to enter the intersection before other vehicles
  • White band slanted to the left: allows buses to turn left
  • White band slanted to the right: allows buses to turn right
  • White bus light: allows buses to go straight or turn left or right
  • White triangle: acts like a yellow light for buses
  • Horizontal white band: acts like a red light for buses

Emergency vehicles

At traffic lights, emergency vehicle preemption allows these vehicles to obtain the right of way over all other road users. In Montréal, only fire trucks have this right of preemption.

Fire station preemption

  • Fire fighters receive an emergency call.
  • Nearby traffic signals receive a preemption request from the fire station to clear the approach to the intersection where the fire truck is arriving (its light turns green) to leave it a clear path through.
     

Directional preemption

When a fire truck travels in a predetermined direction, the traffic lights in that direction will turn green to clear the approach to the intersection. This clears the fire truck’s path.

These two types of preemption save precious seconds of time that can in turn save lives.

Test your knowledge of traffic lights