The Pierre-Laporte Bridge is sicker than we thought. Before the end of December, the Ministère des Transports du Québec (MTQ) will have to carry out emergency replacement work on two suspension cables that support the bridge deck. The trucks will be diverted towards the center of the bridge to avoid any excess load on the sides of the structure, and engineers from the Department will be on site at all times “to ensure that there are no other elements. which may affect the capacity of the bridge ”.
According to information obtained by Press, the condition of certain lines was deemed sufficiently serious by MTQ engineers for them to manufacture a temporary support to lighten the loads on these cables and to secure the structure in the event of failure.
The hangers are these numerous vertical steel cables, attached to the two large carrying cables of the bridge, which are used to support the suspended deck on which more than 125,000 vehicles circulate daily, including around 7,500 heavy goods vehicles.
The MTQ confirmed to Press, late Wednesday evening, that this replacement work must be carried out before the first heavy sails of the winter. The accumulation of snow, specifies MTQ spokesperson Émilie Lord, “could greatly hinder the intervention”.
The lines “are in production”, and work will begin “as soon as they are received, scheduled for mid-December,” said Mme Lord.
The work will result in major closures at night. Two out of three traffic lanes must be cut off in each direction.
The right lane, on the Pierre-Laporte bridge, is already closed to trucks, to reduce the loads on the sides of the bridge, and this “restriction should be in effect until the new lines are put in place”, specified the MTQ.
“Complex and unique”
Driving on the Pierre-Laporte Bridge remains safe, but the unplanned replacement of elements as important as the lines does not represent a serious warning for an infrastructure “as unique” of 51 years old, affirms the president of the Association. Professional Engineer of the Government of Quebec (APIGQ), Marc-André Martin.
The APIGQ has agreed to modify the list of essential services that its members must perform as part of the strike which begins this Thursday, for an indefinite period, and during which the members of the association will refuse to work in the evening, at night and on weekends. Government engineers have been without a collective agreement since March 2020.
But there is no question of playing politics with the safety of the public, and when the Ministry informed us of the situation, we agreed to include the work of dismantling the platforms and replacing the lines, which will be unwind at night.
Marc-André Martin, President of APIGQ
“Given their complex and unique nature,” indicates the internal memo, this work requires the presence of the “designer” from the Directorate-General for Structures and an engineer from the Directorate-General Chaudière-Appalaches.
The president of the APIGQ praised the ingenuity of the MTQ professionals, who had to improvise a temporary support to lighten the loads and secure the lines in the event of failure, while waiting for their replacement.
“This is not trivial as an intervention, insists Mr. Martin. It’s not the kind of job you suddenly do on a bridge of this size, and it’s not the kind of flaw that suddenly appears. ”
A rare suspension bridge
Suspension bridges are rare in Quebec. Of the 9,725 engineering structures listed in the inventory of structures of the MTQ road network, there are… four. Two of these bridges are located over the Saint-Maurice River, in Shawinigan and La Tuque. Their reconstruction dates back to the First World War.
The other two are located about twenty kilometers from each other: they are the Île d’Orléans bridge, built in 1935, at the end of its useful life, and which will be replaced by a cable-stayed bridge; and the Pierre-Laporte Bridge, the youngest of the four, inaugurated in 1970. No suspension bridge has therefore been built in Quebec for more than half a century.
“This work should be an opportunity for the Department to examine the state of its expertise for a bridge that is unique in Quebec, and for which we should have built a team of dedicated engineers a long time ago,” said the president. of the APIGQ. Especially at 51 years old, the Pierre-Laporte Bridge is reaching an age when it will need major repairs. ”