Why Sydney’s worst roundabout is one of many hurdles for our biggest metro line

After worming their way to Olympic Park from a site near Parramatta, two 170-metre-long tunnel boring machines building Sydney’s $25 billion Metro West project faced their next big hurdle: the city’s worst roundabout.

The machines are so large that they have had to be cut into bits to fit under motorway ramps – including those for Homebush Bay Drive over the infamous roundabout next to DFO Homebush retail centre – on their journey on the back of trucks to where they started tunnelling at Clyde.

One of the rail tunnels dug by giant boring machines to the site of the Olympic Park station for Metro West.Credit: Peter Rae

Now, the Metro West project team and the Minns government face their next hurdle. Within months, Australian Turf Club members will vote on controversial plans to sell Rosehill Racecourse to create a “megacity” of 25,000 new homes and an extra metro station on the city’s biggest rail project between Parramatta and Sydney’s CBD.

It complicates construction of the mega-project, which already faces costly and time-consuming work in an area near the racecourse heavily contaminated by more than a century of heavy industry.

Even if turf club members vote in favour by the end of the year, an underground metro station at Rosehill will have to be retrofitted. The boring machines will have passed the site on their way to Parramatta and Westmead by the time designs are completed and planning approval granted.

That means engineers will have to crack through the newly dug concrete-lined twin tunnels to build a station there if, indeed, it goes ahead.

Transport Minister Jo Haylen, centre, in front of a giant cutter at Olympic Park used on one of the boring machines.Credit: Peter Rae

Sydney Metro chief executive Peter Regan said the agency had developed a number of options for constructing a station at Rosehill since the government and turf club unveiled plans last December.

“The tunnel boring machines will go through first, and there is an alignment that provides for that station to be then constructed,” he said.

“We’re working through a range of options and doing design and doing configuration. All of that would then have to go through planning processes and be subject to the broader precinct master plan.”

However, Regan said it was “still early in the design phase” for a station at Rosehill, and the cost would depend on the construction techniques used and its configuration. Meantime, a key requirement is that the tunnels’ alignment under Rosehill is straight to enable a station to be built.

Asked whether the risk of contamination leaching could add to the station’s cost, Regan said the site had been used as a racecourse for a century but was surrounded by “some very contaminated land”.

Extensive remediation works several hundred metres south of the racecourse at Clyde were already under way for Metro West’s giant stabling yards and maintenance facility for driverless trains.

“They are very contaminated sites. It is a slow and, at times, costly process to remediate what often may be over 100–150 years of industrial use and heavy chemical use,” he said.

Internal divisions within the turf club about the proposal to sell the 60-hectare racecourse for 25,000 new homes and a metro station were laid bare at a parliamentary inquiry early this month.

The 27-metre-deep hole dug for the Olympic Park station is one of the largest along the Metro West line.Credit: Peter Rae

Transport Minister Jo Haylen said she remained optimistic that the plans for housing and a station at Rosehill could be realised if the turf club supported it and was willing to work with the state.

“There is no better place in Sydney that has this significant land holding. We have refocused Metro West on the delivery of housing alongside public transport,” she said.

Asked whether she would consider Silverwater or Newington for a station if the turf club rejects selling the racecourse, Haylen said the government wanted to add an extra stop on the line because the best place for housing was “on top of or next to a fast and frequent public transport service”.

The two boring machines, named Betty and Dorothy, are due to start tunnelling from Clyde under Rosehill racecourse towards Westmead early next year.

Metro West is due to be completed by 2032 and will form the fourth stage of Sydney’s metro network. The main section of the second stage – now known as the M1 line – under the harbour and central city between Chatswood and Sydenham opened on Monday, seven years after construction started.

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