Traffic signals

Strathcona County relies on state-of-the-art technology to keep traffic moving smoothly. Transportation engineers and technicians operate and monitor traffic flows using high performance computers, specialized traffic analysis software, advance traffic management systems, electronic/electrical equipment, and traffic control devices.

There are approximately 80 traffic signals that Strathcona County owns and operates.

Image of traffic signals along arterial road in Sherwood Park

The Traffic Engineering and Safety branch of Transportation and Agriculture Services oversees the design, construction, operation and maintenance of the County's traffic signals.

Although traffic signals may seem simple, in reality, their management and operation are very complex. Small changes in one part of the system may have impacts in other areas; therefore, decisions made in traffic signal operation must consider all road users.

Signal coordination and timing

  • 1. How do you decide where traffic signals should be installed?

    As intersection traffic and pedestrian volumes increase, it may be necessary to install a traffic signal. Before installing a traffic signal, several criteria are evaluatedm such as traffic volumes, proximity to schools or facilities, collision history and the positive and negative effects that will result.

    Advantages of traffic signals:

    • Establishing right-of-way of vehicles and pedestrians
    • Reducing right-angle collisions
    • Providing adequate time for vehicles and pedestrians to cross the intersection

    Disadvantages of traffic signals:

    • Can increase overall intersection delay
    • Can divert traffic to other residential streets
    • Can attract additional traffic to the intersection
    • Can Increase rear-end collisions
  • 2. How are traffic signals coordinated?

    Traffic signals in Sherwood Park are mostly coordinated for the main corridors with the goal of moving the greatest number of vehicles through the system with the fewest stops. In signal coordination, the busiest traffic movements are given precedence over the lesser traffic movements.

    We design signal timings to prioritize and balance the needs of all road users, including pedestrians. We aim to review and update signal timings every three years to ensure all traffic signals are coordinated and adequate green times are provided.

  • 3. Why does it seem like some traffic signals are not coordinated at all?

    Traffic signals may not seem to be coordinated in some driving directions because it is not easy or possible to provide perfect signal coordination for traffic movements in all directions. The signal coordination is adjusted at various time periods of the day to accommodate changing traffic patterns.

    When the traffic flow is heavier in one direction, such as heading west on Baseline Road in the morning rush times, the signals are coordinated to favour the highest volume of vehicles. However, coordination for one direction of travel may result in more stops and delays for the other direction with fewer vehicles. Thus, when traffic volumes are relatively balanced, the traffic signals are timed so that the “reds” and “greens” are balanced in both directions. As a result, residents who express concerns about signal timings are often travelling midday or against the higher volumes of vehicles.

  • 4. Do traffic signals operate on the same timing all day?

    Signal timing parameters are adjusted at various periods of the day to accommodate changing traffic patterns. To respond to varying traffic volume levels, many intersections change their operational parameters at least five times per day.

    In general, most traffic signals have four basic timing plans:

    • AM Peak Plan: Monday to Friday, 6a.m. to 9 a.m.
    • PM Peak Plan: Monday to Friday, 3 p.m. to 7 p.m.
    • Night Plan: Monday to Sunday, 11 p.m. to 6 a.m.
    • Off-Peak Plan: Remainder of time

    Some traffic signals also have additional timing plans to accommodate special traffic conditions, such as school drop-off and pick-up hours, community special events, construction detour plans, etc.

  • 5. Why do signal lights no longer flash between 11 p.m. and 6 a.m.?

    The flash mode was removed for several reasons:

    1. When signals are in flash, pedestrian crossing lights don’t operate, leaving pedestrians to cross the road at their own discretion and care. Drivers may not be able to see crossing pedestrians at night, especially if the pedestrians do not have bright or reflective clothing. The lack of signal control and visibility of pedestrians creates a safety concern.
    2. As traffic volume drops after 11 p.m., it is most effective to operate traffic signals in free (non-coordinated) mode, where traffic signals will operate at the minimum cycle lengths. During free operation, traffic signals on the main corridors in Sherwood Park (Baseline Road, Wye Road, Sherwood Drive, Clover Bar Road and Broadmoor Boulevard) will remain green until there is a side-street demand by either a pedestrian or vehicle.
    3. Strathcona County was the only remaining jurisdiction in the Capital Region to use programmed flash during the night. This may have confused visiting drivers.

Signal length

  • 1. Why did I have to wait over two minutes at a traffic light?

    The operating cycle lengths in Sherwood Park range from 80 seconds to 140 seconds.  The level of traffic volumes at every intersection is different; however, traffic signals must operate on the same cycle schedule in order to maintain the signal coordination. In other words, a long cycle length used at a busy intersection must also be operated for intersections that have lighter traffic volumes. This can seem unnecessarily long to individuals at the intersection with lighter volume, but it is necessary to maintain the coordination of all intersections.

    Any wait times longer than two and a half minutes are not normal and should be reported to us through County Connect. We strive to use the latest technology in vehicle and pedestrian detections, but these devices are not fail proof.

  • 2. Why do I have to wait so long at a red light even if there is no traffic?

    Many drivers ask why they have to wait so long for a signal to change, particularly when waiting to enter a major arterial street from a side street. It is likely a result of the direction you are travelling. The overall network looks to balance the experience of all users. If you notice you are the only vehicle waiting, you are likely travelling against the primary flow of traffic.

Vehicle detection at traffic signals

  • 1. How are vehicles detected at traffic signals?

    Strathcona County uses several different technologies for detecting vehicles at intersections.

    Video

    Most of  the signalized intersections use video to detect the arrival of vehicles and to cycle the traffic signals.

    We mount the cameras on either the streetlight extensions or the mast arms of the traffic signal pole. The cameras are connected to a video-processing device where the video images are received and analyzed. This method allows for flexible customization at the intersection and provides  technicians the ability to monitor a variety of traffic and roadway situations, providing quicker response to problems. Video footage is not recorded.

    Inductive loop

    An inductive loop is  a coil of wire buried under the roadway that acts somewhat like a magnet. When a vehicle drives over or stops on the loop, the metal mass of the vehicle changes the characteristics of the magnetic field and generate a signal to traffic controller that  that a vehicle is present.

    All detectors perform best when vehicles stop just behind the white stop line. Vehicles that move past the stop line into the pedestrian crosswalk or stop too far back may not be detected.

  • 2. Why does the detector at a traffic signal not detect me immediately?

    You may feel like your vehicle has not been detected, but that is not the case. The wait time you experience will depend on when the detector was activated during the signal cycle and can range from a few seconds to up to more than a minute. Signal timings vary throughout the day. A wait time of more than two and a half minutes is not normal and should be reported to Transportation and Agriculture Services through County Connect.

  • 3. Can traffic signals detect emergency vehicles?

    Most traffic signals in Strathcona County are equipped with GPS hardware to detect emergency vehicles by receiving a GPS signal, which is broadcast by a GPS device installed in an ambulance or fire truck. This form of detection gives the emergency vehicle priority to proceed through the intersection.

    The Emergency Vehicle Pre-emption system uses GPS satellite technology, radio communications and a manageable mapping system to pinpoint the emergency vehicle.

  • 4. What are the other cameras at intersections used for?

    In addition to the video detection devices described above, you may also notice Intersection Safety Devices (ISDs) and Traffic Surveillance Cameras mounted at several intersections in our community.

    Intersection Safety Device (ISD)

    These cameras enforce speed and red light infractions. ISDs improve safety by reducing both the number and severity of “T-bone” crashes, the most dangerous kind of collision, at the intersection. More information on intersection safety is available here.  

    Traffic Monitoring Camera

    A new device to Strathcona County is the Traffic Surveillance Camera. This device is used to monitor  traffic flow along our arterial corridors. There is no recorded video from these devices nor are they used for enforcement purposes.

     

Pedestrian signals

  • 1. Why does the walk signal not come on even though I have pressed the button?

    There are usually two types of crosswalks installed at a signalized intersection:

    • Automatic triggered crosswalks
    • Electronically triggered crosswalks

    For automatic triggered crosswalks, you do not need to press a pedestrian pushbutton to cross.  The “Walk” and “Flashing Don’t Walk” signals are turned on automatically every signal cycle.  This type of crosswalks does not have designated pedestrian pushbuttons and signs.

    For electronically triggered crosswalks, when a pedestrian pushes the button, a call is sent to the signal controller to turn on the “Walk” and “Flashing Don’t Walk” signals. The pedestrian pushbutton must be pushed for the pedestrian signals to appear. The signals will not usually change immediately but the controller will fit the pedestrian signals into its programmed operation for the particular time of day. The signal controller registers the first time the button is pushed and remembers it until the walk light comes on.

    Pushing the pedestrian button repeatedly or harder will not make the walk signal  appear sooner.  The electronically triggered crosswalks always pair with designated pedestrian pushbuttons and signs. It is important to push the button for the appropriate crosswalk because pressing the wrong button will reduce the intersection efficiency.

    Pedestrian crossing button

    If the button is pushed after the light is already green in the desired crossing direction, the walk light will come on the next cycle because there is not enough time for the signal controller to activate the walk phase of the current cycle.

  • 2. If a signal is malfunctioning, who should I contact?

    Questions and/or concerns about traffic signal operations, as well as requests for traffic signal installation, should be sent through County Connect.

 

Further information:

Coordination and signal timings
Transportation Planning and Engineering
Phone: 780-464-8279
Email: transportationplanningandengineering@strathcona.ca

Operations and maintenance
Transportation and Agriculture Services
Phone: 780-417-7100
Email: transportationandagriculture@strathcona.ca

County Connect

Ask it, report it or suggest it using County Connect

Last updated: Thursday, June 28, 2018
Page ID: 39113