TTC issues RFP for Relief Line South tunnel design

In Canada, the Toronto Transit Commission (TTC) has formally released a Request for Proposal (RFP) for tunnel design work of the Relief Line South. More specifically, the RFP is to “complete the Concept Design Report and Preliminary Design and Engineering for the Tunnels and associated facilities for the RLS, together with a cost estimate and project delivery schedule, to 30% design completion.”

This RFP marks a substantial step forward in the detailed design work for the Relief Line, which is tentatively scheduled to begin construction in 2025 and be complete by 2031. The RFP is scheduled to close on December 15th, with a winning proponent likely announced shortly afterwards.

For planning and design purposes the Relief Line has been divided into two segments: The Relief Line South, which runs from Osgoode Station to Pape Station, and the Relief Line North, which will run north from Pape Station, possibly under Don Mills Rd (though the alignment is far less refined).

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The Relief Line South is being spearheaded by the TTC, while the Relief Line North is primarily a Metrolinx project. The Relief Line South is approximately 6km in length, while the Relief Line North’s length depends on what alignment and terminus is ultimately chosen.

The planning and design work for the Relief Line is being funded primarily through a $150 million funding commitment from the Provincial and Federal governments. To date however, there have been no hard commitments for construction funding from any level of government, though the City of Toronto and Metrolinx continue to push the project forward in anticipation of a multi-government funding commitment in the coming years.

The Relief Line South will feature additions/improvements to three existing stations (Osgoode, Queen, Pape), and will add five new stations to the network (at Sherbourne, Sumach, Broadview, Carlaw, and Gerrard streets).

One new piece of information contained in this RFP is that the TTC is open to the possibility of using “a combination of twin-bored, single or mined tunnels”. Single-bored or mined tunnels would be a departure from how subways have typically been built in Toronto.