Work on a bypass to ease the Inverness gridlock could cause six weeks of jams for commuters, from Tuesday.
The first phase of the West Link, connecting Dores Road to the A82, will run into next year.
By 2020, people should be able to travel from the so-called southern distributor road to the A82 via a new bridge over the River Ness, avoiding the city centre.
It will eventually link the A82 Fort William road to the A9 Perth route and A96 Aberdeen road with a swing bridge over the Caledonian Canal and a low-level bridge over the River Ness.
The first stage, at the Glenurquhart Road-Bught Drive junction, is expected to take six weeks. Lights will operate and motorists are warned there may be “some delays”.
Council leader Margaret Davidson said: “This will deliver significant economic benefits to the city and surrounding area, reduce congestion and enable construction jobs and housing development.”
The council reckons £4 will be generated for the city economy for each £1 spent on building the road.
A £3.75million “developer contribution” has been pledged by housebuilders constructing homes on nearby land.
Planning officials say the West Link will “reduce traffic congestion, improve journey times and support active travel through cycling and walking.”
It was approved two years ago despite a concerted campaign of opposition that still lingers.
Objectors say it will destroy precious green space. New rugby pitches will be created and the Torvean golf course will have to be moved.
Local Liberal Democrat councillor Alec Graham said: “I would have preferred a tunnel. This will mean a lot of pain. But, at the end of it, there will be gain for many residents.”
Based on December 2014 prices, the West Link is expected to cost £36.6million compared with a figure of £34.3million stated in September 2013.
However, due to an extended construction programme and taking inflation into account, the council approved a capital allocation of £43.6million.
