Senior transport officials were questioned at a budget estimates hearing on Tuesday about why both the Airport Metro line and the recently opened M1 extension under central Sydney could not operate around the clock.

Sydney Metro chief executive Peter Regan said it made sense to run a 24-hour service during special events such as New Year’s Eve and Mardi Gras, a move the government had been testing before the city’s M1 motorway opened more than two weeks ago.

“It’s certainly an option, but the way the deal has been structured so far, it’s not something you can do every weekend,” he told the hearing.

“It’s a matter of compromise between cost and patronage, and also a matter of contract.”

The government’s agreement with the private consortium that runs the M1 allows the line to operate 24 hours a day during special events, but this is not possible on a regular basis due to maintenance requirements.

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Services on the M1 line are ending earlier, at 10.30pm Monday to Thursday for the next three weeks, which is deemed necessary due to “essential engineering and maintenance works”. After this work, they will run until 12.30pm on weekdays and 2.30am at weekends.

The new metro line to Western Sydney Airport has largely gone unnoticed compared to the planned $25 billion Metro West between Parramatta and the CBD and the M1 extension. But the airport line was butchered by the country’s peak infrastructure adviser three years ago, warning its costs would far outweigh its benefits.

Once open, the metro journey from Western Sydney Airport to St Marys will take about 15 minutes, while the journey to Bradfield will take five minutes. The airport line trains will be about a foot wider than other Sydney metro trains to accommodate travellers carrying luggage.

Five bus routes to the new airport and Bradfield are set to be launched ahead of the first flights in late 2026. Under Transport for NSW’s plans, buses will run every 30 minutes from 5am to 10pm on the new routes ahead of the airport’s opening in two years.

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