The contractor starts work this week on the Cornish Gateway Services near Bodmin.
It will form the first phase of a proposed mixed-use development on the site including renewable energy generation through two new state of the art wind turbines, a new hotel and commercial development and BP service station.
Construction is due for completion in spring 2014.
The replacement B3193 scheme starts in July to build a new 2.7km route which is due for completion by autumn 2014.
Dawnus Regional Director Rob Williams said: “Regionally we have a very strong civil engineering team, several of whom live within the local community, and they are excited at the prospect of getting the site up and running in the next few weeks.”