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Water infiltration in St. Laurent tunnel prompted closure for investigation, repairs

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Water infiltration into the tunnel at St. Laurent Station caused some damage to ceiling tiles overhead of light rail platforms, leading to a five-day closure of the station while crews worked to fix the issue.

"Areas had been identified where the underside of that roof slab has some very thin slices of the concrete below the reinforcement steel that has become loose," said director of engineering services Richard Holder at a news conference Wednesday. "Through the investigation of the ceiling panels, we discovered some of the supporting elements that are attached to the concrete slab were corroded."

St. Laurent Station reopened for O-Train passengers Wednesday morning, and trains are serving all stations between Tunney's Pasture and Blair.

"Crews were able to successfully complete the required remedial work which was then inspected to confirm that all hazards have been mitigated," said Transit Services General Manager Renée Amilcar. "The station has been cleaned and is ready to receive passengers."

The St. Laurent Station had been closed to riders since Friday after an inspection of ceiling tiles found evidence of corrosion and possible damage to concrete in the underground station. Trains continued to run through the tunnel, but riders had to take buses to connect to the St. Laurent Shopping Centre.

Evidence of corrosion on ceiling tiles at St. Laurent Station, observed May 17, 2024, prompting a closure of the station. (City of Ottawa/supplied)

OC Transpo said Monday that crews had to remove suspended ceiling tiles above the rail platforms and inspect the tunnel concrete. Rail service was suspended and replaced with R1 buses between Hurdman and Blair stations Tuesday night for repairs and additional work.

OC Transpo says the concrete roof slab pre-dates light-rail construction and that section of the St. Laurent Station was originally built to serve buses as part of the Transitway.

In order to reopen the platforms to riders, ceiling tiles were all removed from the tunnel. Future work will be required to replace the tiles. Some mesh nets were also placed in select areas above the platforms over places where future work on concrete needs to be completed. Engineering inspections concluded that any hazards associated with the concrete roof slab and the suspended ceiling structure had been fully mitigated and the station was safe to reopen Wednesday.

The tunnel at St. Laurent Station as it appears May 22, 2024. The overhead ceiling tiles have all been removed following an inspection that revealed evidence of corrosion. (City of Ottawa/supplied)

At a news conference Wednesday, Infrastructure and Water Services general manager Tammy Rose said staff are inspecting options to seal remaining sources of water infilatration. She added the issue identified last weekend is not related to an issue involving falling concrete in January.

Future remedial work will be required in the tunnel, including additional work on some of the concrete above the platforms. 

Riders will also notice some mesh sheets hanging from the ceiling in parts of the tunnel. This is part of future work.

"Our plan was to remove the concrete and not have the risk of any debris falling. Once we got into that specific area, to make sure noting has a risk of falling, we're going to install mesh in that localized area," said director of asset management services Sue Johns. "That area will need more work in the coming months because it's in a temporary state. It is safe and that is an area we will continue to monitor."

A future Ontario Structure Inspection Manual (OSIM) inspection is also upcoming this year, which will involve a more fulsome review of the whole tunnel, Amilcar said.

Issues east of uOttawa raise concerns for Stage 2: Tierney

Line 1 has experienced regular issues since it launched in 2019, including stopped trains, derailments, and multi-week shutdowns, but at least one city councillor in the east end says a pattern has emerged that negatively impacts his constituents.

Beacon Hill-Cyrville Coun. Tim Tierney told Newstalk 580 CFRA's Ottawa Now with Kristy Cameron on Tuesday that the east end of the line seems to have more problems than the west end does.

"I think we're hitting the end of the road when it comes to any kind of faith in the east end past the University of Ottawa," he said. "Think about how many times we've had train issues and it's always east of Ottawa U."

There have been numerous issues on the LRT tracks east of uOttawa Station. Issues so far this year include damaged wires in February and falling pieces of concrete at St. Laurent Station in January. Last summer, the east end took longer to get back online following a full system shutdown that lasted four weeks because most of the curves in the line are east of uOttawa. The September 2021 derailment happened near Tremblay Station. Freezing rain and moist air over the Rideau River (east of uOttawa) suspended service for several days in early 2023.

City and transit staff have implemented several fixes to mitigate many of the problems seen on the line in recent years, including more de-icing measures for freezing rain, lubrication on curves, speed changes, a more stringent vehicle inspection regimen and, eventually, a full redesign and replacement of the axle hubs on all trains.

Tierney says any future suspension of rail service between Blair and uOttawa stations because of regular problems on the line will harm ridership once Stage 2 service out to Trim Road has launched.

"When you're hearing about people having to get on buses to get on trains, you can only imagine with Stage 2 light rail coming into play, if people have to get on trains, get off, get onto a bus, get back onto a train in minus 40, the highest modal split of people getting onto public transit in the east end is going to evaporate overnight," he said. "If you can't tell, myself and my east-end colleagues are pissed off now. We've hit a new turning point."

Tierney said he feels very good about the eastern extension past Blair Station, but that "doesn't solve the missing middle" of Stage 1. 

"People are tired in the east and we're going to lose ridership if we don't get the major spine corrected, as well as Stage 2, when it comes online. This all has to be buttoned up so that we're ready to roll."

With Files from CTV News Ottawa's Josh Pringle

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