Businesses in Argyll are demanding the Scottish Government rethink plans that could see traffic restricted to a single-lane convoy system at the Rest and Be Thankful mountain road for up to four years.
Hauliers, farmers and other businesses staged a protest on the A83 on Saturday, with around 20 large vehicles including tractors and haulage trucks taking part.
Campaigners fear prolonged restrictions during construction of a permanent solution to the landslip-prone route could damage businesses, tourism and communities across Argyll and Bute.
The protest comes ahead of a meeting between campaigners and Transport Secretary Stephen Flynn on Thursday, 29 October.
The Rest and Be Thankful Campaign Group wants ministers to consider alternatives which would allow two-way traffic to continue throughout the work.
Calum MacRae, managing director of civil engineering company A&L MacRae, said the economic consequences for Argyll and Bute could run into hundreds of millions of pounds.
The A83 is a vital route between Argyll and the Central Belt but has repeatedly been closed by landslides and debris flows.
Transport Scotland’s preferred permanent solution involves around 1,370 metres of debris-flow shelter and a catch pit along the existing road, with construction expected to take between three and four years.
During parts of the work, traffic would be diverted on to the Old Military Road below the main carriageway.
Campaigners have instead proposed alternatives including upgrading a forestry track, known as the Green Route, to carry two-way traffic, widening the Old Military Road further or using both routes as part of a one-way system.
Minutes from an A83 Taskforce meeting in March show officials were asked to reconsider alternatives to prolonged convoy working because of concerns over the economic impact.
Argyll, Bute and South Lochaber MP Brendan O’Hara has also launched a petition calling on the Scottish Government to reject a four-year convoy system.
Haulage firms have warned that delays could have a particular impact on trucks trying to reach booked ferry sailings, while farmers and tourism businesses have raised concerns over increased costs and disruption.
Transport Scotland says no final decision has been made on the traffic arrangements during construction.
The Scottish Government has said it remains committed to delivering a permanent and resilient solution to the Rest and Be Thankful as quickly as possible.
Flynn is due to meet campaigners and local politicians on Thursday before a final approach is agreed