OTTAWA — LRT officials on Friday couldn’t explain why the road above a downtown tunnel excavation caved in, forcing workers to pull their equipment to safety.
Tunnelling at the city’s east portal is on hold until the Rideau Transit Group, the city’s LRT contractor, determines the cause of the road collapse on Waller St., south of Laurier Ave. E.
“We can only confirm it was located directly above when tunnel excavation was occurring and at this point we cannot confirm its root cause,” deputy city manager Nancy Schepers said during a press conference.
Geotechnical experts haven’t identified other safety concerns, Schepers said.
“I can assure you that all steps are being taken to, first, protect the public and all physical assets in the immediate area. I can also assure you tunnelling will not resume until both ourselves and RTG are comfortable it is safe to do so.”
Around 10 p.m. Thursday a crew was excavating using the Crocodile Rouge roadheader machine when a worker noticed dirt was spilling down from above. Work stopped immediately and no one was hurt.
According to RTG construction director Tim Stewart, the collapse happened above the crown of the tunnel, which is about five metres down from road level. The tunnel itself, which is protected by a spray concrete called shotcrete, didn’t collapse.
It was only Wednesday that work crews started working on that the tunnel around the clock.
There is no word when the investigation will be done and when tunnelling at the east portal will resume. Schepers said the costs will be the responsibility of RTG.