Motorists are to face traffic chaos until Christmas when work begins to reduce congestion and cut congestion times between Scotland’s biggest cities.
The carriageways will be reduced to two lanes in both directions and various slip roads will be closed at times.
The project is designed to cut the commute from Glasgow to Edinburgh by around 20 minutes.
Graeme Reid, project manager, said: “Transport Scotland is working with the contractor to ensure these works are completed as quickly as possible.
“Whilst we’re doing everything we can to minimise the disruption, delays will be inevitable, so we’re asking motorists to check the Transport Scotland and Traffic Scotland websites for updates on these key routes, to plan their journeys in advance and to look at taking an alternative route if possible.”
Work on the M74 will begin on 8 August between junction 2A Fullarton and junction 6 Hamilton and will last around three months.
The project on the M8, which connects Edinburgh and Glasgow, will begin in the middle of August between junction 10 Easterhouse and junction 8 Baillieston and last around four months.
On the M73, work will begin in the middle of September between junction 1 Maryville and junction 2 Baillieston and last around six weeks.