Impacts of Speed Limit Changes

Speed Limit Changes in Isolation

In general, most research has found that reducing speed limits, in and of itself, does not cause significant changes in operating speeds. This conclusion was identified in the best practices review that was carried out for the 2015 Traffic Calming Policy update and was reflected in the Policy: the Policy does not support reducing speed limits as a traffic calming measure unless the speed limit change is accompanied by physical changes to the street to encourage lower speeds.

In terms of safety and collisions, research about the effectiveness of speed limit reductions has produced mixed conclusions, with some studies indicating sli ght reductions in collision rates and others indicating no change or slight increases. Overall, it is unlikely that there would be a measurable safety benefit from lowering speed limits from 50 km/h to 40 km/h without other measures to encourage lower speeds.

Speed Limit Changes as Part of an Overall Strategy

Reductions in operating speeds have a clearly demonstrated safety benefit, both in terms of reducing the likelihood of collisions as well as the severity of collisions that do occur.

Reduced speed limits would be an important aspect of an overall speed reduction strategy, since lower speed limits would allow lower design speeds and target speeds, which would in turn allow changes in City design standards that would encourage lower speeds.

Impacts on the School Neighbourhood Policy

The School Neighbourhood Policy was adopted by Council in 2016 (CR645/2016). At the time, the total capital cost to implement the Policy was identified as $1.8 million; due to price increases, the current estimated cost to implement the Policy is $2.3 million.

The majority of this cost is for “40 km/h when flashing” signs in school zones.

The School Neighbourhood Policy does not require “40 km/h when flashing” signs on streets where the prevailing speed limit is 40 km/h. Because of this, reducing the speed limit to 40 km/h in residential neighbourhoods has the potential to reduce the cost to implement the School Neighbourhood Policy significantly. With a 40 km/h speed limit on all local residential and Class 2 Collector roads, the estimated cost to implement the School Neighbourhood Policy would be $320,000 (i.e. a reduction of $1,986,000 from the current estimate of $2,306,000).

If the School Neighbourhood Policy is modified, the impact of a 40 km/h speed limit reduction may vary. The School Neighbourhood Policy is due for its 5-year review in 2021; this review has not yet begun.