The mystery of trucks vs. the Guy St. underpass
Despite laser warning system, it’s been struck three times in just over a month
The Guy St. underpass that serves as a conduit to downtown Montreal for as many as 10,000 morning rush-hour rail commuters a day is once again a victim of abuse.
In just over a month, three trucks have collided with the rail bridge, snarling traffic and forcing passengers to disembark at the Vendôme station and finish the rest of their journey into town by bus or métro.
In mid- September, a trucker was forced to deflate his tires to get unstuck from under the bridge. The driver of a Tim Hortons truck wedged his vehicle under the underpass at 6:30 a.m. on Thursday, Oct. 11. It took a tow truck two hours to free him, and earned him a $160 ticket. On Wednesday of last week, the suburban train authority Exo reported another truck collision with the underpass.
This is not the first time the bridge has been a trouble spot. But the recent spate comes as a surprise, because after years of getting whacked on a regular basis by the trailers of eighteen-wheelers, the undersized underpass had finally been getting some respite.
Once the victim of as many as 50 collisions a year, including one month in 2010 when trucks ran into it at least 10 times, accidents had practically stopped, thanks to an innovative early-warning laser system developed by a local engineer in collaboration with the city, police and rail authorities.
Although the collisions did little to the underpass, they often created lengthy delays for passengers. Traversing the underpass are Canadian Pacific Railway tracks that serve three commuter lines before trains arrive at their last stop in downtown Montreal at the Lucien L’Allier station.
Each time a truck strikes the underpass, engineers have to be dispatched to the bridge, just south of René-Lévesque Blvd., to ensure the CPR rail lines had not been knocked out of alignment, a procedure that takes at least 30 minutes and often longer.
Since collisions with the bridge can peel back the top of the trailers like a sardine can, they are also an issue for trucking companies and presumably for the career prospects of truckers.
At 3.75 metres, the bridge’s clearance height is 0.4 metres (or about one foot, four inches) less than the standard of 4.15 metres. The reduced clearance is not unusual for a Montreal span, but truckers need to be aware to avoid striking them. Truckers are issued maps outlining bridge and underpass heights, and there is a Cargo Mobile app, developed in conjunction with the city and Transport Quebec that outlines potential routes and clearance heights.
After years of incidents and irate passengers and drivers, the city of Montreal commissioned a study and pilot project to solve the problem. Engineers determined they could not dig down and lower the street, at least in the short term, because of the cost and complexity of moving underground infrastructure like water mains, sewage pipes and electrical conduits. Installing a horizontal, warning bar on chains of the type often used in parking garages to warn drivers of low clearance levels was deemed ineffective for semi-trailers because the high point of the truck — the trailer — is behind the driver, who might not hear when it hits the warning bar. Signs telling truckers not to use the street went unseen or ignored.
In 2012, the city opted to install sensors to alert drivers if their loads were too high. Laser beams were affixed to a lamppost at the corner of Guy St. and René Lévesque Blvd. that monitored the height of trucks heading south. If an oversized truck passed through, it triggered flashing lights on an illuminated sign on the underpass reading “Impact!” along with a video image showing a truck smashing into the underpass.
In the five months after the warning system was installed, at a cost of $150,000 for development and installation, paid for by Agence métropolitaine de transport de Montréal, which manages the train system (AMT, now called Exo), the city said no trucks had hit the underpass. About 12 trucks a week were being warned away.
This week, the city of Montreal said the bridge has been hit by trucks only “half a dozen times” since the sensors were installed six years ago.
“The results obtained with the virtual height-clearance barrier are compelling,” said Marilyne Laroche Corbeil, a spokesperson for the city of Montreal’s communications department. “By reducing the risks of collisions, this project helps by maintaining traffic flow and ensuring the reliability of public transit.”