Sydney's Rosehill Racecourse could be relocated and replaced with 25,000 homes in the city's west as part of revamped plans for the Metro West announced on Wednesday.

Key points:

· The NSW government has released details of their plans for new, high-density housing at rezoned sites across Greater Sydney

· It includes the potential relocation of Rosehill Racecourse for 25,000 new homes and a new train station

· More than 200,000 homes will be built including 138,000 properties at areas near rail stations

The plans released by the NSW government confirmed the multi-billion-dollar Metro West project will go ahead, after months of being stuck in development limbo due to concerns over cost and timeline blowouts.

A memorandum of understanding has been signed by the Minns government and the Australian Turf Club (ATC), following a proposal to redevelop Rosehill.

It is set to be replaced by thousands of homes and a new Metro West station, an addition to previous plans for the underground rail network.

That is part of a broader plan to build 138,000 new dwellings at rezoned sites in 31 suburbs and 47,800 homes near eight major transport hubs, with the latter being completed over the next 15 years.

"It's the biggest thing we will ever do as the government. If this comes off, put it that way," a spokesperson for the premier said.

Relocation of Rosehill

The plan involves completely relocating Rosehill Gardens Racecourse to make room for 25,000 new properties, green space and a Metro station.

It's not yet known where the racecourse will be moved to but the government has flagged a number of sites as possibilities. 

The government is working on the proposal with the ATC, who are investing $5 billion into the joint plan.

Besides the relocation, those funds will also go into rebuilding and developing existing racecourses and facilities at Warwick Farm and Royal Randwick.

A centre of excellence horse training facility will be constructed at Horsley Park to accommodate the relocation of 300-400 horses from Rosehill Gardens stables.

Rosehill racecourse will be gradually moved to a new site by the end of the decade, according to the ATC.

Homes to be built up, not out

The NSW government's signature housing policy is focused on building up, not out.

The ambitious goal, announced in more detail after part of it was mistakenly published this week, aims to deliver 210,800 homes.

As well as the 25,000 proposed homes on the Rosehill site, the Minns government will rezone land around metro and train stations in almost 40 suburbs.

In the first stage, Bankstown, Bays West, Bella Vista, Crows Nest, Homebush, Hornsby, Kellyville and Macquarie Park will all undergo rezoning, with the aim to build 47,800 homes within 1200 metres of transport in those suburbs in the next 15 years.

Premier Chris Minns said the state government would provide $520 million to those communities, for infrastructure to support an influx of people, such as road upgrades and open spaces.

"I want NSW to be a state that is affordable for the next generation of kids with great transport options to make work and life easier," he said.

A second stage aims to deliver 138,000 new dwellings, by rezoning another 31 suburbs for higher density housing within 400 metres of their metro or train station.

Those suburbs are Adamstown, Ashfield, Banksia, Berala, Booragul, Canterbury, Corrimal, Croydon, Dapto, Dulwich Hill, Gordon, Gosford, Hamilton, Killara, Kogarah, Kotara, Lidcombe, Lindfield, Marrickville, Morisset, Newcastle Interchange, North Strathfield Metro, North Wollongong, Rockdale, Roseville, St Marys Metro, Teralba, Tuggerah, Turrella, Wiley Park and Wyong.

The government will offer developers in those zones a fast-tracked approvals process, called a 'state significant development', to ensure apartments are built quickly.

 

NSW Premier Chris Minns has pledged $520 million to build up infrastructure at the key sites.(AAP: Dan Himbrechts)

It will be offered to developments over $60 million, and construction must start within two years of approval.

The government has previously confirmed it would take control of planning laws around town centres across the state, to enforce the building of mid-rise residential apartment blocks where they are allowed.

It means councils cannot block a proposed apartment block because of its height, if the area is zoned for apartments.

New plans for Metro West

Within a month of taking office in March, the government announced a review into Metro West, after being briefed that cost had blown out by at least $12 billion.

After months of deflecting questions on the project's future and refusing to rule out cancelling it, the government has finally committed to finishing the underground railway.

Up to two stations will be added to the line, which was originally planned to have nine stops between Sydney CBD and Westmead.

Under the existing route, the widest gap between stations is a seven kilometre stretch from Sydney Olympic Park to Parramatta.

 

The Sydney Metro West has been under a cloud since the Minns government came to power.(ABC: Chantelle Al-Khouri)

Sydney Metro will undertake scoping studies for as many as two new stations west of Sydney Olympic Park.

If the deal to relocate the Rosehill Gardens Racecourse comes off, a station would be built there.

NSW Transport Minister Jo Haylen said the proposal could deliver the type of housing and public transport links Sydney needs.

"This is a once in a generation opportunity to build the  housing that our city needs next to new public transport that our city needs as well," she said.

When Metro West was announced by the former Coalition government, it was spruiked as a 20-minute connection between Parramatta and the CBD.

But the Labor government says the focus is no longer on a 20-minute journey. Its priority instead is putting more housing along the train line.

It says each additional station would add 90 seconds to the trip.