The Rest and Be Thankful Campaign has won cross-party support from local MSPs and councillors for its call to transport minister Jenny Gilruth ahead of the Scottish Government-led A83 Task Force’s next meeting on Thursday.
The main route between Glasgow and Kintyre has been frequently blocked by rock and debris falls despite millions of pounds being spent on fencing and “catch pits” in an attempt to prevent landslips reaching the road.
Some of the landslides have also forced the closure of a parallel diversion route below the A83 in Glen Croe, known as the Old Military Road, which is also single track so traffic has to use it in convoys.
Vehicles are also switched to that route during heavy rain, while at other times the most at-risk section of the A83 is narrowed to a single lane controlled by traffic lights, which has caused delays.
Campaigners said an interim route on the opposite side of the glen, labelled as green, was the best option and should be approved.
A permanent bypass could involve viaducts and tunnels, and take around ten years to complete.
John Gurr, who chairs the campaign, which represents 1,500 Argyll businesses, told The Scotsman: “It’s been two years since the landslides closed the road for 200 days and we still do not have a fully functioning two-way road which stays open when it rains.
“We have 60,000 lorry journeys over the Rest and Be Thankful each year and delays [caused by remedial work] are costing an extra £2 million to get goods in and out of the county.
"We have for the first time I can remember asked our elected representatives at all levels of government to send a message with one voice to the transport minister in advance of the task force meeting, asking for a decision.
"Our MP, MSPs and councillors across Argyll and all parties have written to the minister: Make a decision on the route this Thursday and set up a funded project to deliver it rather than wasting any more time.
"The green route is the cheapest, quickest to build and least disruptive."
Gurr argued that it should have been approved at the task force’s last meeting in March.
The Scottish Government’s Transport Scotland agency said it would announce plans for an interim diversion route by December, and a permanent bypass in the spring.
A spokesperson said: “We are committed to a long-term solution to landslip risks at the A83 Rest and Be Thankful and the transport minister will update the A83 Task Force this week on the work taking place.
“Potential route designs are being progressed and these range from traditional roads and localised structural protection to full tunnel options.
“We are also progressing work to develop a medium-term resilient route through Glen Coe while the long-term solution is developed.
"We will bring forward proposals for this by the end of this year.
"This work includes considering using the existing forestry road, improvements to the Old Military Road and other options.
“We expect to announce a preferred route option for a long-term solution by spring 2023.”