On Tuesday at 9am, barriers will go up at both ends and the pass will close for two months.

During the closure, drivers will have to use the detour routes of Lawrence Hargrave Drive or Mt Ousley Road.

Roads and Maritime Services has said traffic on these routes “will be higher than usual”. The closure is to install a 1.1-kilometre rock fence that is 3.5-metres high.

“The fence is being installed on the escarpment, which can only be accessed on foot or by using cranes and other lifting machinery from the road,” an RMS spokesman said.

“Heavy posts [weighing] 200 kilograms each and fencing will need to be lifted carefully into place from the road, drilled and installed without damaging the surrounding rainforest canopy.”

The closure is required because the equipment being used is too large to allow vehicles to pass safely.

Also, there is an increased risk of rock falls during the work.