By James Jackson
For the Post
The Region of Waterloo says yellow light times are fair and safe, and take into account variables that can influence safe stopping.
“We are setting yellow appropriately, it’s accounting for the speed (and) it’s accounting for the length of time it takes for someone to perceive and react to a yellow,” said Thomas Schmidt, regional transportation commissioner.
“There isn’t a safety concern related to the length of yellow lights here in the Region of Waterloo.”
Currently, the region sets the length of yellow lights — referred to as a yellow light interval — at four seconds in areas with speed limits between 40 and 60 kilometres per hour. The interval increases to 4.2 seconds in a 70 km/h zone and 5.4 seconds in an 80 km/h zone.
Schmidt said Waterloo meets or exceeds provincial guidelines. The provincial minimum is based on a perception time of one second and assumes the driver is travelling at the posted speed limit.
The region’s timing is also in line with what the National Co-operative Highway Research Program (NCHRP) in the United States suggested in a recent report.
The NCHRP recommends an approximately five second increase in yellow times for every 10 km/h increase, starting at 3.3 seconds in a 40 km/h zone. The organization assumed drivers are travelling about 10 km/h over the posted limit.
An increase in yellow times would not necessarily lead to fewer crashes or injuries, Schmidt said, and the region already accounts for some real-world conditions by surpassing the provincial minimum.
Schmidt said evidence suggests drivers on city routes are going approximately the posted limit.
The design of streets influences the speed of traffic more than light intervals, said Schmidt. He said wide-open roads tend to have higher traffic speeds.
Drivers approaching intersections are sometimes caught in what traffic experts call the “dilemma zone” when the light turns yellow. There might not be enough time to make it through the intersection before the light turns red, but not enough space to safely stop.
Schmidt said lengthening the yellow would not solve that problem because some drivers would perceive the change and adjust their driving accordingly.
“Extending it would not make things safer and would not necessarily reduce red light running,” Schmidt said.
On top of the four-plus seconds for yellow lights, the region also uses an all-red signal for two seconds to give vehicles already in the intersection enough time to exit, meaning there is actually a gap of at least six seconds between when the light first turns yellow to when traffic in the other lanes get a green.
Schmidt said the times are constant throughout the region, whether there is a red light camera at the intersection or not.