The Toronto Transit Commission (TTC) is embarking on a new subway extension program by adding Relief Line South to its downtown transit network. The main purpose of this program is to alleviate ridership capacity issues on the overcrowded main subway lines. 

This extension is approximately six kilometres long with five new stations and modifications to three existing stations.  The new subway line utilizes very deep twin-bore tunnels to avoid utility conflicts and intersections with the existing primary subway lines.

AECOM is providing architecture and engineering design for the two most complicated Relief Line stations located in the core of downtown Toronto. Metrolinx — with its partners the City of Toronto and TTC — are advancing the planning and environmental assessment of a rapid-transit line extension to relieve crowding and provide more travel options to current and future transit riders in Toronto.