Car/cyclist crash stats support speed drop: London study

As motorist speed increased, the probability of cyclist injury increased.

Rebecca Henderson // Special to Western NewsThis graph shows how as motorist speed increases, the probability of serious cyclist injury increases in the event of a crash.

A Western-led analysis of 12 years of car/bicycle crash data in London points to one clear conclusion about the most important variable in whether a cyclist is seriously injured or not – motorist speed.

Not weather, time of day, distraction, age of drivers or cyclists, nor even the location of collision, says Rebecca Henderson, a Health Sciences PhD candidate. Specifically, cyclists always experienced an injury if they collided with a vehicle travelling more than 40 kilometres per hour (km/h).

While cycling advocates and motorists have offered opinions to city hall on how to improve cycling safety on London streets, Henderson said her research offers concrete evidence for concern. The data bolsters local advocacy to reduce speed limits to 30 km/h on local streets, down from the current default of 50 km/h.

“In London, what it does is it drives it home in a way other information may not,” Henderson said. “We have data that shows unequivocally how people are getting hurt in the city of London. There are not a whole lot of factors except speed. And the only way we can control speed is by changing the speed limit.”

She studied 1,656 crashes between 2006-17, analyzed cyclist injuries (as identified by polices) as either minimal or serious and then correlated those injuries with a number of factors that might have influenced the extent of injuries.

“The only one that made a difference was speed,” she said.

While ‘higher speed equals more injury’ seems to be a logical conclusion, Henderson said the city now has the numbers available to back it up.

Graph showing probability of injury between cyclists and motorists, depending on motorist speed

Rebecca Henderson // Special to Western NewsThis graph shows the proportion of cyclist injuries in crashes with motorists, depending on motorist speed. In crashes where motorists were travelling more than 40 km/h, cyclists were received minor or severe injured in every instance – the severity of injuries directly proportional to motorists’ speed.

At motorist speeds of higher than 40 km/h, 13 per cent of cyclists suffered severe injury. At 60 km/h, the proportion of severe or catastrophic injury increased to 27 per cent.

By contrast, at a speed of 30 km/h, severe injury or death to a cyclist was less than 10 per cent.

Henderson presented her data to London’s Cycling Advisory Committee, of which she is a member. The committee endorsed Henderson’s research, and the city’s Civic Works Committee will debate a speed-limit change when it meets in September.

In London, there’s an increasingly vociferous conversation about safe cycling – a debate that includes the cost and benefit of more protected bike lanes and a call for more on-road courtesy and rules-following by cyclists and motorists alike.

“When we think about cycling, I really want to back down the us-versus-them language,” said Henderson, who describes herself not as an activist but as “someone who drives a car and someone who rides a bike.”

This still-unpublished study brings an angle to the injury-prevention discussion that wasn’t available before. More than a matter of pitting one person’s opinion against another’s, she said, this study provides evidence to support a policy change that benefits public health.

“This is one of the pieces I’m really passionate about – study data that can be applicable to our policy decisions.”

She noted Montreal recently decided to reduce its speed limits to 30 km/h on city streets and to 40 km/h on arterial streets.

Speed limits in London school zones are already 40 km/h.

Maximum vehicle speed on most roadways on Western campus is 40 km/hr, and 20 km/h in some high-traffic-volume areas.