Ontario Concrete Pipe Association
447 Frederick St N2H 2P4 Kitchener, ON, Canada

http://www.cbc.ca//ottawa-sinkhole-174-unger-investigation

http://www.ctvnews.ca//with-bridges-crumbling-why-do-we-st Interesting article with insightful comments from Samir E. Chidiac, Ph.D. P.Eng. Chair in Effective Design of Structures & Professor, Department of Civil Engineering McMaster University

http://www.cbc.ca//ottawa-sinkhole-hwy174-accesstoinfo-upd Given the large area of steel wall missing and the volume of water and the speed of the water flowing through the culvert at the time of inspection, Professor El Halim would have made the right decision and demanded immediate actions.

http://www.cbc.ca/player/News/Canada/Ottawa/ID/2297240497 Interesting news report on Highway 174 Sinkhole