The early work for the approved interchange has already begun, following the awarding of the construction contract to Fulton Hogan in January.

Transport for NSW Regional Director South Cassandra Ffrench changes have been made ahead of the detailed design work beginning.

"Refinements have been made to the scope and design of the interchange to ensure it will improve safety and access to and from Wollongong, support freight growth and improve traffic flow whilst delivering value for money," Ms Ffrench said.

These changes include removing the roundabout on the eastern side of the overpass and replacing it with traffic lights "to improve efficiency for traffic moving between the M1, Wollongong and the University of Wollongong".

A map that makes up part of a March project update also shows a second signallised intersection further east along Mt Ousley Road.

Also a planned pedestrian bridge over Mt Ousley Road from Dumfries Avenue is no longer part of the design.

"Instead, Transport for NSW will deliver other improvements to cycle and pedestrian connections along and across Mt Ousley Road," Ms Ffrench said.

"The design of these will be progressed as part of detailed design and shared with the community in the coming months."

The existing pedestrian overpass linking the TAFE and the University of Wollongong will remain in place and be widened.

"During this work, a temporary closure of the pedestrian bridge will be required," the project update stated.

"A detour will be in place via University Avenue overpass. The project is investigating opportunities to minimise the impact of this closure."

Night work on the project is also taking place until April 18, which will see occasional closures of the shoulder and slow lane of both sides of the motorway between Mount Ousley Road and Northfields Avenue.

"We are on track to starting major work at the end of this year on this critical piece of infrastructure, that will not only improve travel times for motorists but also provide safer journeys and support growing freight movements to the South Coast," Ms Ffrench said.