REM tunnel underneath downtown rejigged to work around salt corrosion

Montreal -

The REM digging deep under Montreal is going as usual -- full of hiccups needing creative solutions.

Last year, as workers dug under downtown, into the old EXO tunnel, they discovered something unfortunate: serious corrosion from salt that made the tunnel walls unsound.

The solution? Metal tubes filled with concrete that workers are using to create a rust-proof canopy. Under it, new arches will be installed.

"It forms an umbrella," said Christian Ducharme.

"It enables us to come after, dig out what’s underneath and install new arches."

The arches are a fairly quick fix, and can be finished as quickly as two weeks, though they add more costs to the project.

For a glimpse of the underground work, watch the video above.