The city of Montreal has come up with a way to tackle the recurrent problem of transport trucks getting stuck beneath overpasses with a new device at one of its most problematic overpasses on Guy Street, south of René Levesque.

The device is an overpass detector with laser beams and a flashing panel.

François Niro, an engineer and transportation advisor with the city of Montreal, credits his son’s garage door opener for the inspiration.

“We’re in the garage working, and I want to close the garage, and he crosses the laser beam and the garage opens up again. That’s it. I mean, it’s really simple,” Niro said.

The detector, installed near the overpass, has invisible laser beams which are triggered by tall vehicles.

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A truck is stuck under a rail overpass on Guy Street in downtown Montreal. This used to happen about once a week before the detector was installed. (CBC)

If the beam is triggered, it means the truck is too tall to fit under the overpass, and a panel lights up warning the truck driver not to enter.

“With the pictogram … we have the truck hitting the structure, so everyone understands it easily,” Niro said.

“I think that’s a good idea. It’s a smart move because that should be everywhere with lower overpass,” said Alain Lalancette, who’s been driving trucks for 35 years.

Lalancette says sometimes drivers don't believe the warning signs.

“They are crossing their fingers, because they know the truck is that high.”

Since the sensor was installed over a year ago Niro says only one truck has hit the overpass.

One device costs $150,000. The one on Guy Street was paid for by the commuter train authority.

Niro says he'd like to see other cities adopt the model.