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17th Avenue SW Traffic Light Improvement Updates

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​The Manager of Traffic in the Roads Department has been working throughout 2015 to better manage traffic control measures in order to reduce travel time and provide safe crossing for pedestrians and CTrains on 17th Avenue SW from 45th Street to Sirocco Drive. The following improvements have been made to the traffic signal coordination on 17 Avenue SW between 45 Street SW and Sarcee Trail SW. These improvements will allow for better traffic flow on 17 Avenue SW with reduced delays.

  • The traffic signals on this section of 17 Avenue SW at the Sarcee Trail, 47 Street and 45 Street intersections are now operating with coordinated timing plans in the AM peak.
  • The eastbound left turn signal (arrow) at the intersection of 17 Avenue and 45 Street has been increased by 10 seconds in the AM peak. Please note that the coordination at 17 Avenue and 45 Street will vary as a result of alternating eastbound and westbound left turn signals. Due to the shared use lanes in both directions, this alternating phase operation is required to provide these turn signals during the same period.

There is a train pre-emption required for the traffic signal operation at the intersection of 17th Avenue and Sirocco Drive/Costello Boulevard SW. The intersection of 17 Avenue & Sirocco Drive requires a relatively long track clearance time. This provides for a green indication for southbound traffic just before and while the gates are descending.  This is crucial to avoid potential collisions between trains and vehicles. Because train pre-emption is random and trains operate very frequently during peak hours, several signal cycles in a row can be affected. This “track clearance” green indication includes a southbound left-turn signal that is only served with pre-emption.

In 2015, the City replaced the traffic signal controller at this intersection with a more advanced controller. With this, several changes were made to the operation.

  • The westbound left-turn from 17 Avenue onto Sirocco Drive was revised to allow this turn during LRT pre-emption. Now, the westbound and westbound left turns are the first to be served after track clearance. At other times of day, the westbound left turn can be served during pre-empt if the pre-empt lasts long enough. It is only during the PM peak that the control measures start the pre-emption with the westbound left turn, as the eastbound has significantly higher volumes than westbound left for all other times of day. 
  • The control measures delay the north-south green light from starting immediately after pre-empt in the PM peak.  This allows pedestrians getting off the train enough time to get to the pushbutton after pre-emption, in order to activate the walk when the north-south green light begins.
  • Control measures allow pedestrians on the north and south crosswalks to proceed during LRT pre-emption.
  • Once pre-emption is concluded, control measures return to the motorists who have been waiting the longest.

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