Experts warn a $12 billion plan to build a train line to Melbourne Airport will face further delays and cost blowouts despite Anthony Albanese’s vow it is a done deal, because the engineers required to make it happen are working on other Victorian government projects.

A steering committee of senior officials from the airport, the state government and the Commonwealth will be set up under a memorandum of understanding announced on Thursday that commits them to finalise how construction of the project can begin.