Sydney motorists to get a wider M5

It is the traffic jam posing as a motorway, but the M5 in Sydney will give motorists a reason to cheer with parts of the ongoing widening project set to be completed in two weeks.

"If we say we are going to do it, we will do it, and if we see congestion, we will try and take it away," Premier Mike Baird said.

Eastbound, a third lane will stretch four kilometres from Camden Valley Way to the Georges River bridge in Liverpool.

This will be shortly followed by an additional westbound lane from the Georges River bridge to the Beech Road exit.

"That means the people of south-west Sydney will be spending more home time and less traffic time," Roads Minister Duncan Gay said.

The entire $400 million project will see the M5 fattened up from four to six lanes for 22km west of King Georges Road to Camden Valley Way.

It is designed to fit in seamlessly with construction of the West Connex project.

Tolls on the existing M5 are due to expire in 2026, however, to pay for the West Connex, the expiry date may be reviewed.

"As we look at financing options in the future, that has to be something we consider," Mr Gay said.