Instead, Illawarra residents looking to catch a train to Sydney for work rather than drive the extra distance on a detour route will have to make do with the existing services.

A Transport for NSW spokeswoman said there was already enough room on South Coast services.

“There is capacity on some existing train services for those wishing to make alternative transport arrangements during the Bulli Pass closure,” a spokeswoman said.

NSW Trainlink load data suggests there are seats for every commuter when a morning peak train arrives at Helensburgh.