Hi,
I am not at home at the mo, and will not be home for several more days, BUT ..... I have NSW forebears who were road contractors back then, ERR .... from around 1800 to say 1920s ! I am on e reader, so I cannot do live links, and I cannot even check out my suggestion BUT ....
Try TROVE with key words "road contractors" I think you should find the Advertising in the early newspapers, perhaps as early as Gov Macquarie circa 1810 looking for people to repair the roads in and around Sydney Town. If so, I think you should also be able to establish that road contractors not only built roads, but also maintained the roads (sometimes failing to maintain the roads too !) .... Some of my rellies were road contractors for several generations in the Western Division of NSW, repairing potholes, grading the roads after heavy rains, etc, re-routing after river courses altered especially on Anabranches of the river, or with heavy flooding altering Distributaries of the rivers .... especially during with during Cobb & Co era. So Road Contractors also needed good understanding of bridge constructions as well as the actual building of the roads in various locations.
Hope this helps.
Cheers, JM