A $1.6 billion Melbourne "sky rail" project was kept secret by the state government to avoid a political backlash, a court has been told.

Residents’ group Lower Our Tracks Incorporated is taking legal action to prevent the construction of an elevated rail track that would remove nine level crossings on the Pakenham-Cranbourne line.

They’re seeking a declaration that the government’s decision to allow the sky rail is improper.

Documents lodged in the Victorian Supreme Court ahead of a hearing on Thursday claimed the government decided to pursue elevated rail after winning office in November 2014.

One of Labor’s key policies leading up to the election was the removal of 50 level crossings across the city.

“After winning office, the state government secretly changed the plan to an elevated railway knowing that such a change of plan would cause substantial political criticism and electoral damage,” the group’s documents say.

“The change to an elevated railway was conducted under a strict policy of secrecy, which was intended to keep the community in ignorance of the change to an elevated railway.”

LOTI’s barrister Philip Hayes said there was “not one skerrick of evidence” the elevated rail plan was put to the community for consultation before the project was publicly announced in February.

The group’s legal argument hinges on an “unreasonable” decision made by Planning Minister Richard Wynne under the Planning and Environment Act 1987.

His decision meant there was no requirement for public panel hearings about the elevated rail, the court heard on Thursday.

David Batt QC, for the government, said there was extensive public consultation after the project was announced.

“People could, and did, make submission about noise, amenity and design,” he said.

Panel hearings would have led to unnecessary duplication of this process and delay, Mr Batt told the court.