Motorists are advised that Broughton Pass is closed in both directions this morning.
Emergency repairs are under way on the bridge due to damage caused by a truck crash on Monday night.
It is understood the truck's driver attempted to cross Broughton Pass between Wilton and Appin, but his vehicle got stuck.
Motorists are urged to use the Hume Highway as a diversion. Wollondilly Council workers are at the scene.
Broughton Pass will remain closed until the repair works are complete.