The work on the Fort York walls consisted of piles and caissons running parallel with the tracks for 115 metres. The second part of the project involved two shafts on either side of the tracks, 20 metres deep and 5 metres in diameter, connected by a 55-metre-long and 3-metre diameter tunnel under the tracks. The tunnelling began from the north shaft while work continued in the south. The shafts were built using a slip-form technique.

The mechanical work consisted of two 600 mm stainless steel force mains, a 300 mm stainless steel watermain, and four 100 mm Bell conduits. All of these run the complete length of the tunnel and raise the shafts at each end, terminating outside for future connection.