Bear Scotland is facing a storm of protest over proposals for multiple closures on the A828 road.
Motorists would face a 90-mile diversion, via Tyndrum and Glencoe, and critics say the plan would spell disaster for businesses in the villages between the two towns, which rely on passing trade.
Jimmy Hanlin, who runs Ben Lora café in Benderloch, said the closures, scheduled for next month, would ruin trade.
He said: “They want to close the road from 8:30am in the morning till 7pm at night.It is madness, a disaster for businesses, who is going to come along here? People will just stay clear.”
Lewis Morrison, who runs Ledaig Motors and Ledaig Leisure, in Benderloch, added: “Daytime road closures are unheard of and lots of businesses will be tremendously affected, there are so many delivery vehicles and wood lorries going past here and there are all the hotels, it’s just insane and ill-advised.
“They are going to spend £700,000 on road improvements but it could cost the West Highland economy millions.”
Workers who commute to different parts of the area would also be hit by the planned road closures.
Les Hazelgrave, who lives in Oban but works in Port Appin, said: “I think it’s a ridiculous situation, how am I going to get to work? It’s probably an 80 mile detour if that road is closed, which is unacceptable.
“I think this is somebody sitting in an office somewhere that hasn’t got any comprehension about what the West Highlands is like and what tourism means in this area.
“It will affect all the small businesses at one of the peak times and I doubt this would happen in Glasgow or Edinburgh.”
Argyll Nationalist MSP Michael Russell agreed with the critics of the plan and said: “It’s a ridiculous proposal which will be very damaging to the whole area, for all the businesses but especially tourist ones.”
The company, announcing the proposed closures, said that 14 different improvement schemes would be carried out on the A828 between North Connel and South Ballachulish.
A Bear Scotland spokesman said: “The programme will allow multiple schemes to be completed at the same time minimising the overall impact on local residents and commuters over the year.”