LRT tracks could shut down for weeks to fix crumbling concrete at St. Laurent Station

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The structure was originally constructed around 1985 and comprises a series of concrete rigid frames cast sequentially end-to-end, along with two adjacent steel truss pedestrian bridges.

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The report outlines renewal work recommended on the upper-level platform, the lower-level platform and an intermediate concourse level providing connections between the lower-level LRT system, the upper-level bus system and the St. Laurent shopping centre.

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An image from an engineering report on the St. Laurent LRT Station shows severe corrosion on a south brace steel member of the east bridge. Photo by Stantec Inc. /HANDOUT

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The renewal on the upper level would apply polymer membrane waterproofing to areas of the tunnel deck top that are not currently waterproofed, along with “leakage mitigation measures” in areas with ongoing leaks, the report states.

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That work would be completed in three stages to avoid closing the station during the construction period. The upper-level construction costs are estimated at $1.6 million and would take about 12 weeks.

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The renewal of the pedestrian bridge would involve re-coating the accessible truss components, jacking of the superstructure and replacement of the bearings, replacement of the wearing surface membrane on the stairs, repair of the membrane on the deck, concrete patch repairs and other miscellaneous repairs.

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Service at the St. Laurent LRT station was restricted for several days in May 2024. Photo by Ashley Fraser /POSTMEDIA

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The 2024 inspection found concrete “delamination” over the tracks that required minor chipping to remove loose concrete, officials said at the time. St. Laurent Station was closed for five days in 2024 to patch the ceiling and to install wire mesh.

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Leakage has been an ongoing issue at several locations, according to the Stantec report, with water pooling in publicly accessible areas. Repairs would involve crews accessing the ceiling above the overhead catenary system (OCS) powering the trains.

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“Within the tunnel, there are several large areas of delamination and spalling in the soffit, particularly along the expansion joints where water has leaked,” the report states. “Deteriorated concrete falling from the soffit onto the LRT station platform poses a serious and ongoing risk to the travelling public. Concrete falling where maintenance staff may be present and onto the rail lines is also a significant concern.”

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The majority of soffit repairs are near the OCS “and will require track closures … Accessing the soffit, which is more than seven metres above track level, to complete the rehabilitation work is both challenging and costly,” the report states.

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An image from an engineering report showing corrosion and deteriorating concrete at the St. Laurent LRT Station. Photo by Stantec Inc. /HANDOUT

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The report cites the temporary concrete scaling and meshing installation in recent years to mitigate the risk.

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“The City wishes to develop a comprehensive soffit rehabilitation strategy, as well as rehabilitation measures for the other tunnel elements and the pedestrian bridges,” the report states. “Given the ongoing safety risks associated with deteriorating soffit concrete, the challenges and frequency of temporary repairs that have been completed in recent years, and the significant disruptions to LRT service that are required to complete comprehensive soffit repair works, the City wishes to develop a rehabilitation strategy with a service life of 15 years, during which minimal repairs are required.”

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