Signalling of the Toronto subway

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The Toronto subway uses a variety of signalling systems on its lines, consisting of a combination of fixed block signalling and moving block signalling technologies.

The oldest signalling system is known as automatic block signalling and was designed for the system's heavy rail lines: Line 1 Yonge–University, Line 2 Bloor–Danforth and Line 4 Sheppard. Since 2022, Line 1 had been fully converted to automatic train control (ATC).^[1] The remaining lines use ATC: Line 3 Scarborough uses an early form of ATC known as transmission-based train control (TBTC), while Line 1 along with Line 5 Eglinton, a light-rail line under construction, use a modern form of ATC called communications-based train control (CBTC).