Why Friday is the most dangerous day to drive on Hwy. 401

A CBC analysis of five years of traffic data shows more car crashes happen on Highway 401 on Fridays than any other day of the week.

Analysis of 5 years of data shows an average Friday has 35 crashes

Police officers attend the scene of a fatal crash on Highway 401 last year near Kingston, Ont. Data shows that more collisions on the highway occur on Friday than any other day of the week. (Lars Hagberg/The Canadian Press)

If you're about to hit the road before the long weekend, take care. 

A CBC analysis of traffic data collected over a recent five-year period shows more collisions occur on Highway 401 on Fridays than on any other day of the week.

Statistics provided by Ontario's Ministry of Transportation show 9,288 collisions on Fridays between 2011 and 2015, the latest period for which data is available.

That's about 35 crashes every Friday. 

Two people were injured in this vehicle rollover on Highway 401 near Pickering, Ont., this summer. (Sgt. Kerry Schmidt/Twitter)

Sundays are the safest

"Basically, Fridays are busier. There's more traffic on Friday, and you will end up with more crashes on Friday as a result," said traffic safety expert Brian Malone of the engineering firm CIMA+.

By contrast, Sunday is the safest day of the week, with 5,961 collisions over five years, or roughly 22 per day

Highway 401 saw a total of 53,279 collisions between 2011 and 2015. Many of them involved more than one vehicle, which added up to a whopping 101,196 vehicles involved in crashes over the five-year period.

Because the 401 is such a busy highway, the ministry prefers to measure its safety relative to traffic volume. 

"Average freeway collision rates in Ontario are low and range from 0.3 to 0.7 collisions per million vehicle kilometres travelled," Ministry of Transportation spokesperson Bob Nichols said in a statement.

The ministry could not provide a breakdown of the collision rate specifically for the 401.

"While traffic volumes generally continue to grow each year ... the number of fatal collisions occurring on Highway 401, and throughout the province, is trending down and has been for many years," Nichols said.

There was, however, a small uptick in fatal collisions on Highway 401 in 2014 and 2015, with a corresponding increase in the number of crashes in which there were injuries or property damage only.

Malone said that since 2009, the number of fatal collisions has started to creep up across North America — but not in Ontario.

"Ontario is still dropping a bit in terms of its total number of fatalities," Malone said, adding that he warns against drawing conclusions from a slight increase like the one seen in 2014 and 2015.

Nearly 30 vehicles were involved but no injuries were reported in this multi-vehicle crash on the 401 near Woodstock, Ont., in 2014. (The Canadian Press)

Tractor-trailers often involved

More than half of fatal collisions on Highway 401 during the five years of data involved at least one tractor-trailer.

Of the 100 crashes between 2011 and 2015 in which someone was killed, tractor-trailers were involved in 54 of them.

While the data also shows that more collisions happen in the winter — due to weather conditions, traffic volumes, and fewer daylight hours — on average, winter accidents aren't more deadly than at other times of the year.

"You may have a lot more fender benders and rear-enders and little crashes," Malone said.

"But they are at lower speeds and therefore they don't extrapolate directly into fatalities and injuries. Summer months, higher speeds … that's where those outcomes can be worse."