A higher speed limit on one of the busiest stretches of CityLink and a more efficient crash response system have been proposed as part of negotiations between Transurban and the Andrews government over a potential new toll road in Melbourne's west.

The owner of CityLink has pitched a $5.5 billion road project for Melbourne, including a new bridge across the Maribyrnong River, widening of the West Gate Freeway and a new connection to the Port of Melbourne. Transurban would win a 10-15 year extension of its concession deed and the right to charge higher heavy vehicle tolls in return for building the road.

The government is yet to accept the proposal to build the Western Distributor but has spoken favourably of it, having this year cancelled the East West Link just before work was scheduled to begin on the $18 billion road project.

As part of negotiations, measures aimed at improving traffic flow on the Monash Freeway have been proposed.