Updated September 29, 2022 at 1:30 pm: Links to TTC reports have been updated to point to the “new” TTC website except in cases where the report is no longer online. In those cases, a copy from my archives is linked on this site.
Updated April 4, 2015 at 6:00 am: The review of options for consolidation of the signal contracts by Parsons is now available as part of the TTC’s report online. Comments have been added at the end of this article.
Recently much attention has focused on the runaway project to extend the Spadina Subway north to Vaughan with a flurry of questions about project management, scope creep and cost controls. Another of the TTC’s megaprojects, one that is actually far more critical to the subway as a whole, is the replacement and upgrading of the signal system controlling the movement of trains. This project has dragged on for years while riders endure service problems with antique equipment and line shutdowns for installation and testing of the replacement system.
At its recent meeting, the TTC Board approved a proposal to restructure existing contracts for new signal systems and to simplify the signaling technology that will emerge as the standard on Yonge-University (Line 1) by 2020 with the remainder of the subway system to follow.
In order to make sense of the evolving design for new TTC signals, this article will begin with a short history of the system as it existed and the limitations the new system is designed to remove.