Left turn arrow –off Columbia onto westbound McGillivray

Public works recently conducted a study to see if there was enough traffic volume to meet criteria to install a left arrow off Kenaston Common Drive onto eastbound McGillivray.

The study indicated all criteria was met and a left green arrow was installed at Kenaston Common and McGillivray .

  • Residents have now requested public works study installing a left turn arrow off Columbia onto westbound McGillivray.

Please know the engineers have guidelines and criteria they must meet before installing. The update they provided me indicates essentially – there is not a large enough volume of traffic exiting on Columbia and turning westbound to meet criteria. A left turn arrow will not be installed at this time.


To benefit from a left turn arrow, the left turn vehicular volume must represent a significant portion of the total intersection volume and experience delays in excess of one signal cycle on a regular basis.

  • Occasional gaps in the opposing traffic flow and/or the amber clearance light generally accommodates at least two left turning vehicles per signal cycle.
  • To meet engineering criteria of a left turn arrow at this intersection, the left turn demand must exceed two vehicles per signal cycle for at least four hours of a typical weekday and more than 25% of the left-turning volume must be delayed by more than one signal cycle during the highest hour during the peak traffic period.

Following the study, it was determined the northbound left turn does not satisfy the minimum 2.0 vehicles per signal cycle criteria.

Traffic safety is also considered.

  • During the most recent three year period for which collision information is available, the reported collisions involving left turning vehicles on these approaches are not indicative of a safety problem with these maneuvers.

In consideration of the information, Public Works does not recommend the installation of left turn arrow phases at McGillivray Boulevard and Columbia Drive / Kenaston Common Drive at this time. With the implementation of the eastbound and westbound left turn arrows, the cycle lengths have been increased in length.