LRT tunnel incident not 1st safety incident since construction began

The collapse of some steel material on the side wall of Ottawa's light rail transit tunnel is at least the fourth incident and third this year to prompt an investigation from the Ontario Ministry of Labour.

• 3 workers rescued fromLRT tunnel near U of O
• Tunnel 'structurally sound' after incident stranded 3 workers, says LRT consortium

Three workers hadto wait for clearance from emergency responders before leaving the tunnel after a steel mesh cage separated from the tunnel wall, according to one of the senior engineers on the LRT project.

One worker suffered a minor hand injury, while the other two were unhurt.

The incident pales in scope to the two times sinkholes have formed during digging, including at a location just south at Waller and Laurier in 2014.

Here in the map below we take a look back at each of the four incidents, and where along the tunnel path they occurred.

• View a full screenGoogleMap of tunnel construction safety incidents