The deterioration of a staging bridge in downtown Montreal forces the Montreal Transit Corporation (STM) to divert one of its main bus routes. The Quebec Ministry of Transport (MTQ) imposed a weight restriction while waiting to repair a structure near the site of a collapse in 2011.
“It is estimated that by eliminating the passage of some heavier vehicles, we can keep the structure open for traffic,” says Sarah Bensadoun, spokesperson for the MTQ.
In November 2017, an inspection on the St-Urbain Staging Bridge revealed numerous defects. Engineers recommended close monitoring because of the “risk of falling concrete fragments”.
The 49-page report illustrates the extent of the problems, with several “watch” items being targeted. On several beams, the reinforcements are apparent and show signs of advanced corrosion. Steel cables, called strands, are cut in several places.
“After this inspection, it was determined that additional studies were needed,” said Sarah Bensadoun. After receiving the results last August, the MTQ decided to impose a weight limit of 18 tonnes.
“There is no risk of collapse. We want to ensure the safety of users based on structural capacity, “said Ms. Bensadoun. Some 13,300 vehicles travel there every day, 7% of them trucks. The MTQ is currently planning repairs. For the moment, the extent of the work to be done or when it will take place is unknown.
This area of the Tunnel Expressway is notorious for the collapse of a concrete structure in July 2011. Parasols, a device to prevent motorists from being dazzled by the sun, had collapsed on the highway Ville-Marie, near Saint-Laurent Boulevard. The accident had not injured anyone, but had forced the MTQ and the City of Montreal to tighten up the maintenance of the road structures.
“There is no connection between the louvers and the load limitation. It is not at all the same nature nor work nor important, “says M me Bensadoun.
Impact on the STM
This 18-tonne limit is close to the weight of a STM bus. A diesel-powered vehicle weighs about 17 tons when filled. The hybrid models weigh a little more because of the presence of a battery on the roof while the articulated weights still more.
The Montreal carrier made the decision in December to stop using its buses on the Saint-Urbain overpass. Line 55 normally follows this route to Old Montreal. This is one of the busiest routes, with an average of 18,700 people using it every day. At the morning rush hour, about one in five passengers passes through the Saint-Urbain Staging Bridge.
Since mid-December, STM vehicles have had to make a detour. They are now turning on René-Lévesque Boulevard to take the Rue de Bleury to cross the Ville-Marie Expressway, this overpass having been redone in 2015. In addition to Route 55, two circuits of the network of night are also diverted, the 361 and 363.
“It happens very rarely that tracks are moved because of weight limitations,” said Isabelle Tremblay, spokesperson for the STM.
Although the detour extends the route by approximately 1 km, the STM ensures that this does not, however, affect the frequency of passage of buses, this circuit being part of the service network every 10 minutes maximum.
In particular, the entrance to Fire Station 20 of the Montreal Fire Department gives direct access to the Saint-Urbain Staging Bridge. After discussions with the city, the MTQ allowed fire trucks, which exceed the weight limit, to circulate despite everything. The number of their passes is not high enough to represent a problem.
His neighbor too
This is not the only staging bridge in the poor area that is subject to weight limitation. Nearby, the one that allows Saint-Laurent Boulevard to span the Ville-Marie Expressway – and which is also used on the northbound bus route 55 – is also subject to weight restrictions. This is however higher, at 24 tons, which does not prevent the passage of buses.
“It has no impact on the 55 because our buses, both empty and loaded, are under 24 tons. In no case does one exceed this weight, “assures Isabelle Tremblay.
The fact remains that the buses must currently be diverted from Saint-Laurent Boulevard because of a subsidence below the roadway a little further north. The incident over the weekend is unrelated to the condition of the overpass. Buses must pass through Jeanne-Mance in the area. For the moment, the City does not know when the artery can reopen to traffic, as studies are still underway to determine how to repair the whole thing.
Note that these two structures in poor condition that are subject to weight restrictions were built in 1972, just like the one that was on the rue de Bleury and had to be redone in 2015. Another structure built in 1972 requiring repairs is also in the area, Avenue de l’Hotel-de-Ville, but it is closed to traffic from the recovery of the Ville-Marie Highway, near the CHUM.
Asked to comment, the Plante administration believes that “this situation illustrates the lack of maintenance and underinvestment in mobility infrastructure. This is why [the] administration invests heavily in road infrastructure and public transport too long neglected, “said Genevieve Jutras, press secretary of the mayor. Montreal is to unveil today the list of projects planned for 2019.