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Left-turn Signal – Pembina/Dalhousie/Bairdmore (south) Intersection

Oct 23, 2020

I’ve received many requests for the installation of a left turn signal at Pembina/Dalhousie/Bairdmore (south) intersection. I had the engineers in the Public Works department study this intersection in 2017 (See Report) and then had them go out this past summer and look at the intersection again. I am not thrilled about the update, but – appreciate they studied this again:

  • A North bound left-turn signal phase is not warranted at the Pembina/Dalhousie/Bairdmore (south) intersection.

A cycle-by-cycle observation was undertaken during the PM peak period and the collision history was reviewed. This intersection meets the primary criterion (left turn demand exceeds two vehicles per signal cycle for at least four hours of a typical weekday). However, none of the additional criteria are satisfied and therefore the overall warrant is not met.

CRITERIA for LEFT TURN SIGNAL INSTALLATION:

To warrant installation of a separate left turn phase, the primary criterion of the Technical Guideline and Practice must be fulfilled: the left turn demand must exceed two vehicles per signal cycle (60 vehicles per hour) for at least four hours of a typical weekday.  If the primary criterion is fulfilled, the left-turn phase is considered warranted if either of the following are satisfied:

  1. More than 25% of the left-turning volume are delayed by more than one signal cycle during the highest hour during the peak traffic period;
  2. More than 12 collisions involving left-turning motorists (same approach) for the most recent three year reporting period.

OR if any of the following two are satisfied:

  1. The average number of left turns during the intergreen (the time between the green signal displays, i.e. the amber and red signal displays) exceeds 2.0 PCUs (Passenger Car Units). The PCU count does not include vehicles established in the intersection during the green phase and clearing on the amber/red phases.
  2. On an approach with two or more through lanes, over the course of an hour, the queue from an exclusive left-turn lane spills back and blocks the adjacent through lane during more than 30% of the cycles.
  3. The left-turn transit demand exceeds 3 in-service vehicles per hour.