Why Sydney will end up with three incompatible metro train lines

Sydney’s new driverless metro trains and stations might end up looking the same to commuters but key differences in the mega-projects mean the city is set to construct three lines run by three separate private operators with trains that cannot be switched between them.

The use of different power and trains built by separate manufacturers will make the new $11 billion metro line to Western Sydney Airport at Badgerys Creek incompatible with the first two stages of Sydney’s metro rail network.

The airport line will use a 25 kilovolt alternating current to power the trains when it opens in 2026 while the Metro Northwest and Metro City and Southwest lines will operate on 1500 volt direct current.

As a result, the 12 autonomous trains to be built by German company Siemens for the airport line will be unable to run on the Metro Northwest and connecting City and Southwest line. The airport line’s trains will be about 30 centimetres wider than other metro trains to cater for flyers who are lugging bags.

The different electric current also means the 45 driverless trains built in India by French company Alstom for the city’s first two metro lines will be unable to be switched to run on the airport line. Neither will they be able to operate on the $25 billion Metro West line – the biggest of the four lines which is due to open in 2030 – because it will run on 25 kilovolts, too.

The airport line is being designed for trains comprising up to four carriages whereas those for the Northwest and City and Southwest lines can be trains up to eight carriages long.

Transport and planning consultant Alex Gooding said it was highly unusual for metro lines in the same city to be deliberately planned to be as different as the airport line was from both the Northwest and City and Southwest lines.

“We are building a system from the ground up, but the previous government appeared to have deliberately designed a range of incompatible features which makes no sense,” he said.

Gooding said a likely reason for the difference was that building the airport line to match the greater passenger capacity of the first two metro lines would have substantially increased the former’s cost, while it also avoided a “single-private operator monopoly” in Sydney.

“Instead of getting one metro, we will end up with three distinct and, to varying degrees, incompatible systems,” he said.

“Metros in cities overseas tend to have different lines but where possible they are built with consistent rail systems and trains.”

When the main section of the City and Southwest line opens next year, it will be operated by a private consortium led by Hong Kong’s MTR Corporation which runs Metro Northwest.

In contrast, a separate consortium that includes Siemens, Australian infrastructure investor Plenary and Italian company Webuild will construct and operate the airport line.

Gooding said the decision to electrify the Metro West line between the Sydney CBD and Parramatta with 25 kilovolts and set up a special entity to manage that project was likely to result in it having a different operator to the other lines.

The new Labor government last month flagged a major overhaul of the Metro West line as part of a wide-ranging review into Sydney’s metro rail projects.

Transport Minister Jo Haylen said the integration of Sydney’s metro lines with one another and with the broader transport network was important, and was why the Minns government had commissioned a review into the projects.

“It’s important to make sure that these projects are being delivered in a way that works for passengers, and properly embed metro services into the transport network as a whole,” she said.

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Sydney Metro said each line was designed to operate independently to ensure the highest reliability with train configurations to suit the customer requirements of the line. “Sydney Metro has a responsibility to procure rolling stock responsibly, driving optimal outcomes on price and safety for the benefit of taxpayers,” it said.

The agency said it ran competitive tender processes for each project to get the best outcome for taxpayers, which created resilience in the broader transport network and ensured passengers had access to the latest train technology and systems.

The design of the Metro Northwest and the City and Southwest lines was also influenced by the need to convert existing stretches of track such as the Epping-to-Chatswood rail line which, like the existing suburban rail network, operated on 1500-volt power.

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Martin Locke, an adjunct professor at Sydney University’s institute of transport and logistics studies, said one of the rationales for opting for different train builders and consortia was to spark competition in the bidding process for the projects.

“The importance of having standalone metro lines has outweighed the perceived benefit of interoperability. It was designed to provide resilience and avoid the issues that Sydney Trains has had with timetable failures and a system that has been shown to be very fragile,” he said.

The rail lines that make up Sydney’s existing suburban rail system are interwoven, which has frequently resulted in major incidents on one line causing significant delays to train services across the entire network.

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