An £11m road upgrade will reduce congestion on a road connecting the central belt and the Highlands.
The A82 road starts in the west end of Glasgow and ends in Inverness where it links to the A9.
The major works at Pulpit Rock will remove a notorious bottleneck at Loch Lomond, getting rid of traffic lights which have been there for 30 years.
Transport Minister Keith Brown said the upgrade will enable the free-flow of traffic in the area.
He said: "The Scottish Government is committed to upgrading the A82, as set out in the infrastructure investment plan.
"The route sits in one of the most unique and challenging landscapes in Scotland.
"It is important that we carefully plan a solution that fits well with the geographical challenges of this route and better connects the businesses and communities in the Highlands and Islands with those in the central belt, while maintaining the renowned beauty of the area."
The improvements include a new 0.4km section of two-lane carriageway, a viaduct running parallel to the loch shore for 180 metres and the widening of the existing carriageway.
Construction is expected to last a year and its anticipated cost is £11m.
As the road is wedged between Loch Lomond and steep hillside, the works provide "real engineering challenges".
Mr Brown added: "This is an important milestone and signals a step forward with this long-awaited scheme. However, infrastructure projects such as this are huge undertakings and simply do not, cannot, happen overnight.
"The work involves considerable design and development work which is absolutely essential to get the right scheme at the right price and keeping impacts on communities and businesses to the absolute minimum.
"Meaningful engagement with directly affected communities is at the heart of all our major infrastructure projects and we will seek public feedback on this scheme at key stages of the project.
"Scottish ministers remain committed to improving the traffic flow situation at Pulpit Rock and will continue to progress the scheme with a view to completing it at the earliest possible opportunity."
Water-based environmental surveys will be carried out next week on the west bank of the loch between Tarbet and Inverarnan as part of a programme of engineering and environmental surveys on this stretch of the route, which Transport Scotland says will help inform the next stage of design work on the A82.