Toronto subway trackage

The cut and cover technique was used extensively on the oldest portions of the subway system, while newer sections were predominantly or, in the case of the Toronto-York Spadina Subway Extension (TYSSE), which opened in 2017, entirely bored.

Some sections of track run on the surface, the most notable on the heavy rail subway system being the stretch of Line 1 Yonge–University in the median of Allen Road.

However, the former light metro Line 3 was a surface or elevated route for nearly its entire length.

Diamond crossovers (or "scissors crossovers") are X-shaped track assemblies that are used on the heavy-rail subway lines, particularly at terminal stations, to allow trains to switch to the opposite platform or track to reverse direction.

All operating centre-track structures (with the exception of Finch West station, which was partially bored and has three fully separate tunnels) were built using the cut-and-cover method, and there are support columns between the tracks.

However, at the under-construction Avenue and Laird stations on Line 5 Eglinton, which were "mined" rather than excavated via cut-and-cover, all three tracks are housed within single tubular, columnless tunnels.