The total payments made since 2016 to the owner of the Old Military Road, which runs below and parallel to the A83 in Glen Croe in Argyll, are revealed in answer to a Freedom of Information request to Transport Scotland by Catriona Renfrew, who described herself as a “concerned resident”.
They showed payments made to Glen Croe Farm under a “minute of agreement” with the headings of “stock movement”, “readiness”, “use” and “reinstatement”.
Ms Renfrew said the figures were not provided until she appealed to the Information Commissioner after Transport Scotland told her the payments were a “private arrangement” with the landowner.
She claimed the Scottish Government agency “wanted to conceal embarrassing misuse of public money”.
Ms Renfrew said: "I am concerned about the costs associated with the continuing failure to make and deliver a proper plan to address the Rest and Be Thankful disruption, which so badly affects communities and businesses in Argyll.
“This information illustrates a shocking waste of taxpayers’ money, which Transport Scotland attempted to cover up, and further underlines questions about its competence.
"It is very difficult to understand why, given the levels of payments already made, there has been no process to consider the compulsory purchase of the land.”
John Gurr, chairperson of the Rest and Be Thankful Campaign, said: “Whilst shocking, we are in no way surprised Transport Scotland continues to waste taxpayers' money on temporary measures rather than focusing on a permanent fix.
“If there was a proper plan in place, Transport Scotland could have purchased the land twice over and begun building a permanent solution.”
A Scottish Government spokesperson said: “We remain absolutely committed to ensuring continued road access in and out of Argyll and Bute for the benefit of everyone.
"We are working hard to find the right short, medium and long-term solutions.
“Reaching agreement for the use of the Old Military Road provides a suitable short-term solution.
"It means we can reduce the use of the alternative longer diversion, via Crianlarach.”