RobotRisk / TTC (Toronto Transit Commission) / 2024-12-11

Automatic Train Control server outage shuts down entire Line 1

S2 · 12/11
2024 · ~07:00 ET · TTC (Toronto Transit Commission) · Toronto, ON, Canada

Record

Company	TTC (Toronto Transit Commission)
Category	other
Type	outage
Date	12/11 2024
Time of day	~07:00 ET
Location	Toronto, ON, Canada · Line 1
Severity	S2 (minor injury or single-unit damage)
Scale	Line 1 systemwide, ~30 minutes
Confidence	high
Verification	Cited source on file; not independently re-verified
Source	CP24

What happened

A server running the Automatic Train Control (ATC) signalling system's train-routing function went offline for unknown reasons on the morning of December 11, 2024, triggering the system's failsafe and halting all Line 1 subway service from Vaughan to Finch for about 30 minutes during rush hour; the TTC's interim CEO called the recurrence of such ATC issues "unacceptable."

TTC (Toronto Transit Commission) record context

TTC (Toronto Transit Commission) vs other alternatives

other context

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outage context

outage: by category

outage: by year

outage: severity profile

Comparable outage events in other

Sev	Date	Company	Event
S2	2026-05	MTA / NYCT	Subway signal system fault disrupts rush-hour service
S2	2026-03-31	Baidu	Baidu Apollo Go Robotaxis Stall in Traffic During System Failure in Wuhan
S3	2021-07-26	MTA / NYCT	Queens Boulevard Line signal system outage
S3	2019-02-28	SFMTA	Automated Train Control System central computer failure halts subway communications
S1	2017-11	PATH (Port Authority Trans-Hudson)	Signal problem briefly suspends PATH service at 33rd Street

Other TTC (Toronto Transit Commission) entries

None on file.

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