Motoring, public transport, cycling and pedestrian lobby groups are united in their support of sky rail, the contentious plan to raise nine kilometres of the Dandenong rail line.

In a surprising show of solidarity, the RACV, Bus Association Victoria, Bicycle Network, Victoria Walks and the Public Transport Users Association have all endorsed the Andrews government's elevated rail plan to remove nine of Melbourne's worst level crossings.

The plan has provoked a fierce backlash from residents, who fear the rail viaduct will build a barrier between communities, attract crime and graffiti, increase noise from trains and reduce property values.

Residents along the rail line through Melbourne's south-east have also objected to being given scant hint of the decision to rebuild the line above-ground instead of digging a rail trench.