Updated July 29, 2026 — 12:14pm,first published July 29, 2026 — 8:50am

Sydney commuters were hit by hours-long delays after the discovery of a faulty fan inside the M5 tunnel overnight triggered emergency works on Wednesday morning, closing the motorway in the city direction during the peak.

Motorway operator Transurban eventually reopened the 25-year-old eastbound tunnel shortly before midday following emergency repairs, avoiding it causing further disruption during the afternoon peak.

Premier Chris Minns said the closure had thrown many people’s commute into chaos, and the roads minister would seek answers from Transurban about its maintenance schedule and the chances of a repeat incident.

“I know that’s cold comfort for people that were stuck in traffic this morning. I’m genuinely sorry about that,” Minns said. “It’s not good enough.”

The toll road operator had closed the two-lane tunnel to conduct routine maintenance in the early hours of Wednesday when workers discovered safety problems with a fan inside the tunnel. A decision was made on safety grounds about 4.16am to replace the fan and keep the eastbound lanes shut after 5am, despite the looming morning peak.

The ongoing closure caused eastbound traffic to queue back as far as 13 kilometres to Milperra during the morning.

Two cranes and other equipment were called in for workers to replace the fan, which is one of 147 in the eastbound tunnel.

Transurban’s general manager for WestConnex, Denise Kelly, said workers discovered that the fan was faulty during the routine inspection overnight.

“We evaluated it to see whether or not it could be fixed in situ while it stayed up in the roof cavity. That was decided not to be the best course of action, and the best course of action was actually to remove it,” she said.

She texted Roads Minister Jenny Aitchison about 4.42am to inform her of the decision to replace the fan and keep the tunnel closed, and the pair later spoke.

Kelly confirmed that Transurban was aware at the time of its decision that the tunnel would have to remain closed during the morning peak.

“That was the immediate advice to the minister and to the traffic management centre ... that it would be closed for the morning peak,” she said. “We made that call very early, adjusted all of the signs and messaging, and put messaging out on links.”

She apologised to motorists for the major delays caused by the closure, but said that safety had to be prioritised. Transurban is still assessing what caused the faulty fan.

Earlier, Transport for NSW coordinator-general Howard Collins had urged commuters to avoid the motorway “at all costs” due to the emergency works forcing the closure of the city-bound lanes of the M5 between King Georges Road in Beverly Hills and Marsh Street in Mascot.

The agency had advised motorists to use alternative routes to travel into the city, and to plan extra time for the commute. Alternative routes included the M8 motorway and a diversion route sign-posted by the M5.

In December, motorists were stuck in one of the city’s M4 motorway tunnels for hours after a major disruption was caused by two bulges found in the roof of the westbound tunnel beneath Ashfield in the inner west.

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Daniel Lo Surdo is a breaking news reporter for The Sydney Morning Herald. He previously helmed the national news live blog for The Sydney Morning Herald and The Age.Connect via email.

Matt O'Sullivan is transport and infrastructure editor at The Sydney Morning Herald.Connect via X or email.