Australia’s largest toll road operator is facing demands to refund motorists caught in hours-long delays on Wednesday morning caused by the closure of one of the M5 motorway tunnels to replace a faulty fan.

Transurban kept the 25-year-old eastbound tunnel closed until shortly before noon – seven hours longer than planned – while workers replaced the faulty fan, causing traffic to queue as far as 13 kilometres to Milperra during the morning 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.”

Transurban earns about half of its annual $3.73 billion revenue from the 11 toll roads – including the M5 – it controls in Sydney. The Sydney Harbour Bridge and Harbour Tunnel are the city’s only toll roads that are not controlled by Australia’s largest private operator.** **

Traffic counts indicate nearly 10,000 motorists travel eastbound through the M5 tunnel on Wednesday mornings.

Coalition roads spokesman Mark Coure called on Transurban to immediately refund every toll paid by motorists caught in the M5 chaos.

“Thousands of people paid to use what should be a reliable motorway, only to be left sitting in gridlock for hours. Motorists should not be forced to pay for a service they simply did not receive,” he said.

The opposition also demanded the government declare a toll-free travel day on the M5 to compensate motorists for the disruption.

Cars are charged a maximum of $9.15 to use the M5 East between Beverly Hills and Mascot, while trucks are tolled $27.47. The M5 East is part of WestConnex and has distance-based tolls, unlike the connecting M5 Southwest, on which cars are charged $6.06 regardless of the journey length.

Motoring group NRMA said Transurban should consider providing toll refunds on a case-by-case basis to motorists disrupted by the tunnel closure.

“We have more tunnels in Sydney than ever before and more are coming online. The onus is on the government and the toll road operators to work together to minimise these severe disruptions,” spokesperson Peter Khoury said.

A spokesperson for Roads Minister Jenny Aitchison encouraged anyone with questions about toll refunds following the disruption to contact Transurban directly with their concerns.

The toll road operator had closed the M5 tunnel to conduct routine maintenance from 9.30pm on Tuesday to 5am on Wednesday when workers discovered safety problems with a ventilator fan inside the tunnel. A decision was made on safety grounds at 4.16am to replace the fan and keep the eastbound lanes shut after 5am, despite the looming morning peak.

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 the company encouraged any motorists who experienced significant delays to contact its toll-payment system Linkt to discuss refunds.

She apologised to motorists for the major delays caused by the closure, but said the immediate priority on Wednesday had been safely removing the faulty jet fan and reopening the road for motorists by the afternoon peak.

“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 Aitchison at 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.”

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.

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.