Amazingly the only western route out of Sydney across the Blue Mountains is closed for three months due to a failure of a convict built bridge.
For that time the only way out of Sydney westward is the Bells Line of Road, the original circuitous, winding route across the Blue Mountains that took 10 years after first settlement to discover.
The failed bridge at Mount Victoria was built by convicts in the 1830s and has been in use ever since on the major route to western NSW (BTW a route I absolutely hate having to use)