Adrian Verster was just a humble data geek until his girlfriend got hit by a pickup truck.

The crash — which left her with a concussion and memory loss — spurred him to do something about bike safety in Toronto.

This week, Verster published a list on his website of the 50 most dangerous intersections for cyclists in Toronto.

His analysis is drawn from city records of 31,000 bike collisions since 1986.

Lake Shore Blvd. E. and Carlaw Ave., just east of the Don River, is the most perilous cross-street for riders, he found.

Verster, a University of Toronto PhD student and avid cyclist, was inspired to dig into the cycling data by what happened at a different intersection. On Aug. 2, his girlfriend, Kate Cook, was hit by a pickup truck at Belmont St. and Davenport Rd.

She hit her head. By the time Verster arrived at the scene of the accident, she was already being rushed to a hospital.

Cook has no memory of the accident. She doesn’t even recall how the car hit her, or whether she was wearing a helmet. She thinks she may have been walking her bike across the intersection.

In fact, she couldn’t remember anything from the 24-hour period bracketing the impact.

“Doctors were asking her where she was and she was saying things that were ludicrously wrong, like ‘It’s January,’” Verster said. “It was pretty scary.”

She spent two days in the hospital and was diagnosed with a concussion.

The accident gave Verster the impetus he needed.

“I had the data before but I had forgotten about it,” he said.

Taking the coordinates of all recorded biking collisions since 1986 and mapping them to the nearest intersection, he was able to show the worst danger zones for urban riders.

A statistics fiend, he was careful to control for factors that might skew the rankings, such as car traffic figures culled from a city database.

Still, the results have some bugs.

Intersections with heavy bike traffic and few cars land unduly high on his list. Naturally, those intersections see more bike collisions, but they aren’t necessarily proportionally more dangerous than areas with fewer bikes and fewer crashes.

The intersection of Harbord St. and Ossington Ave., for example — ranked 11th — probably isn’t as fraught with risk as the list makes it seem; during rush hour, bikes account for 40 per cent of traffic on Harbord.

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While Verster didn’t set out to make a political statement, his findings could have implications for the city’s cycling infrastructure and street design.

Bloor St. is riddled with dicey intersections: seven spots along the east-west thoroughfare made the list. Queen St. is lined with five such intersections.

“I guess I feel like we need bike lanes on Bloor and Queen,” Verster said.

In June, six city councillors asked the public works committee to order an environmental assessment for a potential Bloor bike lane, earning plaudits from cycling advocates.

Some intersections on the list will come as no surprise, as their odd physical layout makes them accident-prone. Bloor and Parliament meet at a Y-shaped junction that produces confused swarms of traffic, making it number 10 in the rankings.

Bloor St. and Brock Ave., the sixth most dangerous, meet at a T.

Southbound traffic arriving at fourth-ranked Davenport Rd. and Bathurst St., meanwhile, comes barreling down a steep hill.

These intractable characteristics mean that for cyclists, some risks simply can’t be wrung out of the system, said Councillor Adam Vaughan.

“There are significant numbers of streets in the city that are dictated not by engineering but by geography, and they’re the streets that tend to create the most issues.”

Still, some fixes to street design would make a big difference, Vaughan said. “Bike boxes” painted at intersections, for example, allow cyclists to stop at lights in front of drivers, instead of being wedged between cars and the curb.

In 2011, city figures show that 152 cyclists were struck by drivers turning right at a stoplight.