Skipped inspection, warning signs preceded falling concrete in LRT tunnel
City didn't complete scheduled inspection of St-Laurent tunnel in 2022, says compliance officer
Parts of the concrete tunnel atOttawa's St-Laurent LRT Station were showing signs of "severe" and sometimes "very severe" cracking and chipping back in 2020, but internal documents obtained by CBC News suggest some of those problem areas labelled "urgent" weren't patched upuntil chunks of concrete fell onto the train tracks inJanuary.
According to an independent compliance officer, the citydidn't fully inspect the tunnel again in 2022 when it was due for another checkup.
On the morning of Jan. 2, OC Transpopartially shut down LRTservice after it noticed pieces of concrete had fallen from the tunnel onto the tracks at St-Laurent station. At the time, the city's infrastructure department blamed"delamination," when layers of concrete separate from the main slab.
Officialssaid the deteriorationwas "not uncommon" for a structure that dates back to the 1980s when the tunnel was used as a bus transitwaybefore being converted for the LRTConfederation Line.
Internal transitdepartment emailsand inspection reports obtained by CBC through a freedom of information request reveal thecity had hiredengineering firm Morrison Hershfield to oversee the tunnel inspection and fix any issues.
On the afternoon of Jan. 2, a senior structural engineer with the company notedthe team removed "loose concrete" over the westbound LRT track in an area known as "Joint G," where the debris fell from. The team also performed minor "scaling" in another area over the eastbound track a term used to describe boththe flaking ofa concrete surface andthe job of removing loose pieces.
Emails sent over the following weekendshow contractors inspected the tunnel again and removedmore concrete from areas where it posed ahazard, includinga "significant location of concern" that had previously beenidentifiedin the city's 2020 inspection report.
"There is another delamination next to this one, as well. We were able to reach bothlocations and perform some scaling to knock off the loosest pieces," the engineer wrote, adding that he wanted to return two days later to perform more scalingand other work on "deteriorated" areas he didn't have time to address on the weekend.
The engineer added they'd bring a "heavier chipping tool" to remove more material.
Scaling concrete 'urgent': report
In the October 2020 inspection report obtained by CBC, inspectors noted "spalls, delaminations and cracks with efflorescence" (water stains), as well as an "active leakage" in that Joint Garea. Similar concerns were noted on the bus terminal platform above that section, and included a "corroded cover plate," "perforated" steel curb armouring,wide cracks and spalling.
Spalling is the weakening of a concrete surfaceover time and can be caused by moisture or the corrosion of embedded steel, causing pieces to chip away.
The inspection also identified some "very severe" delamination, spallingand cracksranging from narrow to wide along other areas oftheLRT tunnel that year.
At the time, inspectors recommended repairing the concrete specifically,scalingareas of delamination overa timeframe of one tofive years.
The inspectorcategorized the recommended concrete repairs as "minor rehabilitation," but wrote "urgent" under the maintenance timing category.
Engineer Solomon Tesfamariamexplained to CBC thatsuchsigns of external deterioration are expected in a concretestructure that's 37 years old, and whichhas been exposed to severe environmental conditions like those experienced during Ottawa winters.
"It's not really safety [or] critical issues, more [an] operational issue to increase the service life of the asset," explained Tesfamariam,a professor at University of Waterloowho specializes in structural engineering and infrastructure.
RTM requested risk assessment
Emails also show the group in charge of maintaining the Confederation Line, Rideau Transit Maintenance (RTM), raised concerns about the condition of the tunnel infrastructure,which falls under the city's responsibility, questioninghowsafe it wasfor their workers.
"After the incident ... RTM and [train maker] Alstom have some concerns about the condition of the 'legacy structures' as the case of this portion of tunnel,'" reads a Jan. 3 email from RTM'sgeneral managerto the city's engineering director.
"The removals of concrete pieces have mitigated the immediate risk ... but our concern is whether other areas of the tunnel could pose a risk to our staff," the RTM manager wrote.
The manager thenrequested a risk assessment, and asked the city for tunnel inspection records to see if they were"up to date and any risks found during those inspections have been suitably mitigated."
In fact, inspections weren't up to date because the city deferred a full inspection of the tunnel in 2022, according to the light railregulatory monitor and compliance officer.
2022 inspection skipped
Ontario's Ministry of Transportation (MTO)requires tunnel inspections every twoyearsunder its Ontario Structure Inspection Manual (OSIM).
Under the project agreement in Ottawa, LRT tunnel inspections fall to LRTbuilder Rideau Transit Groupand RTM, except for the St-Laurent tunnel which is under the city's jurisdiction.
The compliance officer found the city performed an inspection of oneof the four areas that make up the St-Laurent station,but deferred the remaining threeuntil sometime in 2024 "due to the major rehabilitation work" at the adjacent busterminal. That workwrapped up late last year.
The MTOallowsdeferrals for major rehabilitation, according to its guidelines from 2009.
It doesn't inspire confidence.- Coun. Shawn Menard
During a transit commission meeting last Thursday, the city's linear asset managerScott Laberge confirmed that in 2022, the city skipped inspectingthe areas from where concrete debris had fallen.
Labergetold the commission he wasn't sure if the city would have caught the issue had it fully inspected the tunnel two years ago.
"It's tough to say, chair, when the issue would have occurred," Labergesaidin response to Coun. Shawn Menard, who raised concerns over the lack of inspection.In an emaildated Jan. 7 and obtained by CBC, Laberge was sent a copy of the 2020 inspection report.
"If the delamination would have been present at the time of a 2022 inspection or if it would have happened after that inspection, it's really tough to say," said Laberge at commission.
But in a statement to CBC, thecityexplained that throughout the rehabilitation project from 2022 to December 2023, it "monitored" some of the other areaslisted in the 2020 report that needed scaling "with no changes identified that would warrant immediate action."
WATCH | 'Tough to say'when loose concrete issue began, says asset manager:
Menardtold CBChe was surprised to learn the inspection four years ago may have identified a "precursor" to theincident.
"[It] makes me question why there wasn't work done to rectify it [earlier]," he said. "It doesn't inspire confidence, and it's something that the city needs to take very seriously going forwardif we're going to get riders to take transit and feeling safe."
Tesfamariam, theengineer, warned against the "waterfall effect" of aging infrastructure, which can degrade more quickly and cost more and more to fix without constant maintenance.
"Skipping [inspections] might not be a good idea, but at the same time, skipping it might be the necessary operational requirements because there are other pressing needs," he explained. "So it's a balancing actbetween safety and operational costs."
Thecity declined an interview, but said in an emailed statement attributed to Laberge that astructural engineer did perform a "comprehensive" inspection of the tunnel in response to RTM's concerns, and deemed any hazards to have been"successfully mitigated."
"The work required to address the areas listed in the 2020 OSIM report is complete," Laberge wrote.
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