O-Train service resumes after pieces of concrete chip off main slab at St-Laurent Station

The pieces of concreate found along the light-rail transit track inside the St-Laurent Station tunnel chipped off the main slab of concrete, forcing OC Transpo to shutdown service on the eastern section of the LRT station for seven hours on Tuesday, according to the city.

O-Train service resumed just before 5 p.m. on Tuesday, after a "structural inspection" was completed inside the station connected to St-Laurent Shopping Centre. The city had said "concrete debris" was found along the track, and the O-Train was pulled out of service out an "abundance of caution."

In a memo to council Tuesday evening, the city's acting general manager of Infrastructure and Water Services said the a structural engineering firm determined the concrete chipped off the main slab inside the tunnel.

"Results from the inspection confirmed delamination, which is the separation of the paste layer at the surface, creating an unbonded layer with the main slab," Carina Duclos said in the memo. "With direction and oversight from the structural engineer, sounding and scaling was conducted by a contractor to remove the small concrete pieces that had separated from the main slab."

Duclos says a report from the structural engineer deemed "there are no hazards, and the structure is safe to resume service."

The St-Laurent Bus Rapid Transit Station was constructed in the mid-1980's, according to the city.

"The lower-level tunnel accommodates Light Rail Transit (LRT) and consists of a series of single span concrete rigid frame structures with the upper-level platform partially located on its deck surface," Duclos wrote. "It is not uncommon to see delamination and scaling required in a structure of this age and with this level of complexity."

The city says staff will conduct "routine condition assessments" of the LRT tunnel.

Concrete debris were found along the track inside the tunnel at St-Laurent Station halting service between Blair and Tremblay stations just after 10 a.m. Tuesday morning, with the transit service saying a "structural inspection" was underway.

Last January, the O-Train was shutdown in the east end for six days following a freezing rain storm. The freezing rain caused ice to build up on the line on Jan.4, and the wires broke. Two trains were stranded along the LRT line between Lees and Hurdman stations.