Submissions on the proposal, to widen the M5 East motorway east of King Georges Road to four lanes each way, close on February 19.

The proposal would also involve a new four-lane M5 East tunnel between Bexley Road, Earlwood to Marsh Street, Arncliffe; a new arterial road from the M5 East motorway to the airport and inner southern Sydney; and widening the existing M5 South West motorway.

The Government said the proposal would improve travel times, access to Port Botany and Sydney Airport, and reduce congestion in the corridor and surrounding arterial network.

However, shadow roads minister Andrew Stoner said people in southern Sydney could be sure the proposal would never get off the ground.

Mr Stoner said the Government had announced or reannounced several projects, including the M5 widening, the F6, and south-west rail link, all affecting the south and west of the city, but they had all been delayed or scrapped.

He said a NSW Coaltion government would scrap the Rozelle metro to build the south-west and north-west rail links.

"The original M5 wasn't built very long ago but is already operating well above capacity,'' Mr Stoner said.

"The budget is also in a perilous state in NSW, thanks to 15 years of a broken Labor Government, so it's unclear where the money would ever come from to upgrade this road.'' But NRMA president Wendy Machin said the expansion was "welcome news'' for one of the most congested roads in Sydney.

The NRMA would monitor progress to ensure it met the deadline.

"It is critical that the Government now begins steps to secure funding for the project,'' Ms Machin said.

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