Jones Bros has begun an 11-week contract at the National Sailing Academy in Pwllheli.
The £450,000 contract involves relocating an access road to make way for the building of a new world-class £8.3m sailing academy at the marina.
The 250 metres of new highway are being constructed on behalf of client Gwynedd Council, as part of the NWTRA (North Wales Trunk Road Agency) Framework.
The project has secured around £4m of funding from the Welsh Government, matched by European funds, with £250,000 being provided by Gwynedd Council.
The academy is being developed to accommodate an increasing number of competitions being held at the marina and to create a top facility for local residents and visitors to the area.
The innovative designs for the main building are currently on show at Pwllheli Sailing Club.