A control-centre computer fault shut Montreal's new REM at rush hour — riders trapped

On the evening of 30 October 2023, computer problems at the control centre of Montreal's brand-new driverless REM light-rail network broke service linking downtown Montreal to Brossard at the height of rush hour. The REM announced the shutdown on X around 3:45 p.m.; a backup plan followed around 5 p.m. and operations gradually resumed around 6:30 p.m., with some riders stuck for as long as two hours. CDPQ Infra's Philippe Batani noted service had been halted earlier the same day for the same problem, and that corrective measures had not resolved it.

Chambly resident Taissia Philipovich was trapped for at least an hour in a jam-packed wagon. 'We were so many people in the train, with winter jackets. It was stuffy,' she said. 'The air wasn't there.' Eventually one woman passed out and another passenger called 911. Batani framed the failure as growing pains — 'we're still in a breaking-in period, but this is a problem we encountered for the first time' — adding the whole system had to be shut down so corrective action could be taken.

The second failure was communication. Riders said CDPQ Infra had published nothing since that initial announcement, and passengers who disembarked at Gare Centrale found no shuttle bus options. Quebec Transport Minister Geneviève Guilbault met transit and CDPQ Infra officials the next day and said it was unacceptable not to update passengers faster — especially 'considering the price the province paid for the light-rail network's construction'.

Full peak-hour shutdown; riders stuck up to two hours, one woman passed out; no shuttle buses at Gare Centrale; the transport minister publicly criticised the operator.

The same fault had already halted service that morning — corrective measures that didn't hold were trusted with the evening peak.

Driverless means nowhere to go: a control-centre error strands every wagon at once, so redundancy is the entire safety margin.

Communication froze with the trains: one initial post, then no updates on the website or social channels while wagons sat packed.

On a new driverless system, the crisis plan is the product: backups, shuttle buses and honest updates are what riders actually experience when the software fails.

Operations gradually resumed around 6:30 p.m. Batani said the REM was working to improve communication during service disruptions; the minister's meeting with officials produced a demand for faster passenger updates and shuttle plans for future disruptions.