Work on a portion of Ottawa's $2 billion dollar Light Rail project has been suspended while the City of Ottawa investigates the cause of a massive sinkhole on Waller Street near the Laurier Avenue intersection.

The first sign of trouble was noticed on Thursday night when material from atop the tunnel started falling. The tunnel boring machine was stopped and workers left the area. That's when the road collapsed.

The sinkhole measures 8 metres wide and about 12 metres deep.

'This is soft soil that we're mining through. Our experts are on site every day that we determine what are supports are going to be", said Tim Stewart with the Rideau Transit Group.

There are minimal delays for traffic. The city says its grateful there are no injuries because the sinkhole is just metres away from a busy Rideau Street. Work is now underway to pour cement into the sinkhole to stabilize the road.

The City of Ottawa says it can't say when digging for the eastern portion of the tunnel will resume.