The route for the long-awaited Melbourne Airport rail link was finally released at the weekend, but not everyone is happy, with some transport experts saying the combined federal and state government project had turned its back on billions in funding.

But others, including Ballarat mayor Daniel Moloney, have welcomed the certainty that regional commuters will finally have a direct access to Tullamarine Airport without having to head into the city first.

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The option tabled by the state government will see a new line constructed from Sunshine to the Melbourne Airport. Construction will begin in 2022 and be ready for patronage by 2029 at a cost of $8-15 billion. It will then connect with the Metro Tunnel providing a direct route for travellers from all across the state.

A $20 billion option, which would have seen funding both by a private consortium and the state and federal government to build a dedicated airport tunnel from Southern Cross to Sunshine, was taken off the table.

Committee For Ballarat chief executive Michael Poulton said the committee was determined to keep up advocacy for fast rail, but admitted to some disappointment to the tunnel being ditched.

Ballarat travellers going to and from the airport will have an easy choice to leave the car at home, under the State Government's announcement for Airport Rail.

"A train to Sunshine, then one change to an express train to Tullamarine, will save time and money for Ballarat travellers. The train will no doubt provide a more relaxing way to start and end a holiday or business trip," he said.

"Committee for Ballarat has long advocated for fast, reliable and frequent services to Melbourne and this announcement has not changed our position.

"We will continue to advocate for the 'next generation' of fast rail, capable of delivering a 40-50 min journeys to Melbourne. Such a service is possible with new rolling stock capable of 250km's per hour as promised by Labor in October 2018 prior to the election."

Transport infrastructure minister Jacinta Allan said the announced alignment would provide more options for regional travellers than a direct airport tunnel from Sunshine to Southern Cross, allowing travellers to enter and exit at any stage of the trip.

Ms Allan said those travelling on the Bendigo, Ballarat and Geelong lines will be able to change at Sunshine station while passengers travelling on the Gippsland line could change once at Pakenham or Caulfield and Shepparton line passengers will change at Southern Cross and at Footscray, which the tunnel idea did not allow for.

"The Metro Tunnel alignment delivers more reliable services for regional Victoria - and the Ballarat line upgrade currently underway is paving the way for extra services," Ms Allan said.

"The Ballarat Line Upgrade is the first stage in delivering faster services for Ballarat, and we're getting on with delivering that.

Ballarat mayor Daniel Moloney has backed the state government's announcement.

"We have always wanted a link to the airport, we have hoped for the state and federal government to work together to create one," Cr Moloney said.

"We now have the opportunity to connect Ballarat to the state and the rest of the world. To get on a train to sunshine and connect without having to go into the city, without buses to and from Southern Cross.

"I'm glad we've moved to a position where country rail is now seen as viable transport. Twenty-five years ago, if you went without a car you got on a train, now it is seen as the quickest alternative.

"With the benefit of hindsight, it was hard to convince people to use rail at the time, now the state and federal government can look at the stats and show that rail is becoming the transport mode of choice."

But Rail Futures Institute president John Hearsch raised concerns about how capacity on the existing line would cope. He said the line would not only have to cater for a growing western Melbourne population, but also added six high capacity trains an hour from the airport.

He said he held fears as to whether electrification to Melton, or even Bacchus Marsh would be able to proceed.

"By announcing the plan that six trains will run every hour to the airport, they've effectively crowded out electrification," Mr Hearsch said. "The ultimate capacity on the western side is 23 train an hour, not 24 as there needs to be space for the Gippsland train at the other end. At the end of the day 18 trains will be consumed with Sunbury and airport train, which leaves at most five to Melton.

"They are not going to justify electrification for five trains. The Melton suburban line already needs twice as much as that already."

However Ms Allan some of the Geelong trains would run through Werribee which would free up capacity.

"Running some Geelong services via the Werribee corridor frees up capacity on the Sunshine corridor for additional services to Melbourne's west including Ballarat and Bendigo," she said.

"Future projects on the Ballarat Line are being considered as part of the Western Rail Plan."