By CBC News Ottawa, November 11, 2016
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.
Three workers had to 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.
http://www.cbc.ca/news/canada/ottawa/lrt-tunnel-safety-incidents-1.3846599