The Speed Control System
After the Russell Hill crash, the jury from the Coroner’s Inquest made many recommendations related to the TTC’s signal system and train operation. The change of timing signals to show a flashing red (described above) was one outcome.
On November 28, 2001, the Commission authorized the installation of a
Speed Control System (SCS) on the existing subway system (YUS and BD) and on the Sheppard Subway which was still under construction. The contract was awarded to Alcatel for $29.5-million.
The new SCS will provide continuous on board enforcement of train operating speed limits, as recommended by the Coroner’s Inquest, and will provide enforcement of all signals. The SCS will issue a violation warning to the train Operator when a speed limit is exceeded. If this warning is not complied with by slowing the train, an emergency brake will occur. Emergency brakes will also be applied if a red signal is violated, thus enhancing system safety. The SCS will provide other important safety benefits in the subway, such as enforcement of a stop at track ends and enforcement of a speed limit when a train is travelling in the reverse direction.
The SCS will replace the current Grade Timing method of speed enforcement, which uses timer relays as well as lunar white and flashing red aspects to enforce speed limits. [p. 1]
SCS uses transponders mounted between the rails to communicate with control equipment on the trains. This system enforces speed restrictions, but track occupancy and routing control remain the responsibility of the primary signal system. SCS provides a way for the signal system to communicate directly with the trains without depending on the operator, but it does not control train operation except for enforcement of speeds and emergency stops.
Although the 2001 report claimed that SCS would replace the timing signals with their lunar whites and flashing reds, these actually remain in use in 2015. Decommissioning all of the existing timing signals and their controls would be a complex job better left to a project that completely replaced the signal system.
https://stevemunro.ca/2015/03/30/the-evolution-of-ttc-signaling-contracts/