The Greens want to spend $9 billion on a high-spec intercity commuter rail network to connect New Zealand's most productive regions.

The party wants to upgrade train tracks connecting Auckland, Wellington and Christchurch with nearby regional towns, creating a network of regional hubs.

Eventually, they would like to upgrade the tracks to allow rail speeds of up to 160 km/h - far faster than the current top speed of Auckland's commuter trains, which is 110 km/h, although the actual speed travelled is slower.

As the scale of the economic fallout from Covid-19 becomes clearer, the Government has begun to look at projects to stimulate the economy back to life after the lockdown ends.

The Greens are keen to make sure this round of economic stimulus helps to reduce emissions after copping political flak for the fact that just under half of the Government's last economic stimulus package was spent on roads.

Green Party co-leader James Shaw said the package would "provide meaningful work whilst driving us towards a sustainable, green, zero carbon future".

SIMON MAUDE/STUFF The Greens want to beef up the intercity rail network to stimulate the post-coronavirus economy.

"Building rail creates more jobs than building motorways and helps us tackle climate change at the same time," he said.

The project is split into two stages. The first is to link up three regional hubs with electric rail and making improvements to allow for higher speeds - up to 110 km/h.

The first hub will link Auckland with the rest of the golden triangle: Hamilton and Tauranga and eventually Whangarei. A limited service between Hamilton and South Auckland is slated to begin soon, after Covid-19 related delays.

The second will connect Wellington with Masterton, Palmerston North and eventually Whanganui. Again, limited services exist between Wellington, Masterton and Palmerston North, but the track would be fully electrified and improved.

Commuters in the South Island will also get a hub, connecting Christchurch with Rangiora and Ashburton and eventually Timaru.

The second stage of the project would be to build new higher-speed track that would support "tilt-trains" capable of achieving speeds of up to 160 km/h as well as building bypasses to create faster and more direct routes.

Green party Transport spokeswoman and current Associate Transport Minister Julie Anne Genter said the proposal was an example of Green economic stimulus.

BRADEN FASTIER/STUFF Green transport spokeswoman Julie Anne Genter said the package would provide a real alternative to journeys by car and plane.

"After the Global Financial Crisis, the National Government's economic stimulus solution was a $12 billion dollar programme upgrading a relatively small portion of our motorway network," she said.

"The Greens want a transformational infrastructure stimulus package fit for the 21st century that has economic recovery and climate change front and centre".

The package will be rolled out over ten years, at an estimated cost of $9 billion.

Genter said that the it would bring big cities and provincial centres closer together and create a real alternative to driving or flying.

The proposal is a party policy at this stage and not yet endorsed by the Government.

The current three party arrangement has not been kind to some of the Greens' carbon, reducing initiatives, notably Genter's electric car scheme, which was spiked by NZ First.

The parties are closer together on rail however, with the coalition investing $1 billion in KiwiRail at the last budget. The Government also started a small commuter rail service between South Auckland and Hamilton.

Shaw said that creating an economy that delivered for people and the environment would set the party's priorities when it came to choosing which infrastructure projects to back.

"The Greens understand in government we can prioritise caring for people and the environment and create an economy that delivers that," Shaw said.

"This is our key focus when deciding infrastructure projects with our government partners."