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The casual observer takes in the corner of Bathurst and Queen streets and notes the usual sights: a streetcar island, a Starbucks outlet and a crew of squeegee kids lounging by the wall of the Big Bop club. But a traffic engineer sees something else entirely: a crash in the making. “This is not a good intersection,” says Jeff Muttart, a Connecticut-based professor and traffic guru. “You've got some built-in problems.”

Stand by the intersection at rush hour and you will witness something that conjures up the first corner at the Calgary Stampede chuckwagon race – an endless series of near collisions as vehicles find themselves funnelled into a road that narrows with no warning.

If you're willing to wait, you are virtually guaranteed to see a crash – on average, there's a reportable one at least once every two weeks. And even that dismal statistic is considered a success story. “The only real surprise is that there aren't more crashes,” says Mike Brady, manager of traffic safety for Toronto Transportation Services.

For experts like Mr. Brady, an intersection can be easy to analyze, yet nearly impossible to fix. Bathurst and Queen, for example, is cursed by long-ago real-estate deals that pushed buildings closer to the road north of Queen, forcing designers to drop a lane.

“It's not what I would choose,” Mr. Brady says. “Sometimes you have to work with what you get.”

From a NORAD-style command centre on Don Mills Road, Mr. Brady and his colleagues do their best to make Toronto's vast road network as safe as it can be. At the heart of the operation is a bank of high-powered computers that contain records on everything from traffic-light timing to car crashes, which are broken down into nine categories.

One of the team's constant challenges is the intersection of Allen Road and Sheppard Avenue, Toronto's No. 1 crash spot. Although it has been improved with a series of changes to its signal lights and road markings, it still averages about 1.5 serious crashes a month.

Built in the early 1980s, the section of Allen between Sheppard and Highway 401 is the imperfect child of compromise. To avoid cutting through Downsview Park, designers went with a series of curves, compounding the problems created by a natural rise that complicated sight lines. Worst of all, the road morphs from a high-speed freeway into an arterial road. Drivers must simultaneously follow the curves, change speed and deal with heavy traffic.

“It all adds up,” Mr. Brady says. “With drivers, change is never good.”

His thoughts are echoed by Prof. Muttart, who has spent decades studying how humans behave behind the wheel. “Everything in driver behaviour starts with the law of inertia. As soon as you expect drivers to do something, the probability of a crash goes up.”

Improving the intersection has involved a series of modifications. The first traffic lights were installed in 1981. As the city grew, the intersection quickly became a crash magnet. The most common accidents involved cars turning left. Due to the speeds involved, there were numerous injuries and fatalities.

In November of 1996, an advanced green was added. This reduced the number of left-turning cars getting hit, but created a new problem – cars waiting for the advanced green created backups on the Allen, and cars heading north ran into them, making the intersection the rear-ending epicentre of Toronto.

In the 13 years since, Mr. Brady and his engineers have studied and modified the intersection again and again as engineers try to find the perfect balance between traffic flow and safety. The type of accident has changed, and the number of fatalities has been reduced, but the intersection remains Toronto's top crash site year after year.

“We're doing the best with what we have,” Mr. Brady says. “A lot of vehicles go through there.”

As scientists have learned, drivers react slowly when presented with an unexpected situation. By using simulators and studying actual crashes, researchers have learned that many drivers take between six and 10 seconds to “process” a newly presented hazard, and several more to make a decision and react.

Martin Pietrucha, a Penn State professor who specializes in driver behaviour, quickly identified the root of the sideswipe-crash epidemic at Bathurst and Queen: It stems from what's known as a “violation of expectation.” The worst intersections are deceptive, leading drivers into a trap they don't foresee.

Sudden curves and lanes that end unexpectedly are both proven accident-makers, and Bathurst and Queen has both. “That's two violations,” Prof. Pietrucha says. “That's a tough row to hoe.”

The statistics show the result: a side-swipe and angle collision rate more than 60 per cent higher than that of other nearby intersections, such as Bathurst and College.

Although police don't keep such statistics, Prof. Muttart believes a study would probably show that the majority of the drivers who crash on northbound Bathurst at Queen are either newcomers to the intersection or use it rarely.

“This is the kind of intersection that you learn about through experience. You won't get a lot of crashes with drivers who know the area and are paying attention,” he says. “But with the rest, all bets are off.

“I don't see a lot of advance notice here. You are going to surprise drivers. You violate their expectations.

“As an intersection, it's very artistic. I will give it that.”