The introduction of uniform congestion charging on Sydney's toll road network is back on the table after the NSW Premier, Barry O'Farrell, said the government would "have another look at it".

A commission of audit carried out by a former Treasury official, Dr Kerry Schott and released today, recommends that the government should "investigate toll arrangements and provide options to government on opportunities to make the toll road network more efficient".

It notes that "charging a higher price during peak periods will convince commuters, who do not have to travel during peak periods, to delay their travel until a later time when the price will be lower".

Variable tolling now exists on the Sydney Harbour Bridge in a bid to ease congestion in peak periods, when the toll is higher.

The Herald reported before last year's election that the Coalition had backed the introduction of uniform congestion tolling for the Sydney netowork to create "a fairer deal for motorists".