The construction work on Greater Montreal’s future lightrail network (REM) is indeed the cause of the holes that recently appeared in the wetlands of the Technoparc Montreal, north of the Montréal-Trudeau airport, writes Toronto Star.

https://www.thestar.com/news/canada/2021/09/16/the-sinkholes-near-montreal-trudeau-airport-were-caused-by-the-tunnel-boring-machine.html