Indeed, about 80% of the tracks for the new rail system, including the most expensive bits (across the st Lawrence river, through downtown and dense suburbs, under the Mont-Royal) were on pre-existing railways or rights of ways. The rest was built aboveground next to a highway (with a small branch dug underground towards the airport).

By comparison, the Blue line metro extension is being built from scratch, including expropriations, and the projected cost is CAD6.4B for 5-6km of new tunnels and give stations.