Roadworks outside a remote village could force residents to take a 60-mile detour to reach their homes.
Business owners in Killin fear that the resurfacing of the A827 near Dochart Bridge could also hit trade as the tourist season begins.
Stirling Council plans to shut a stretch of Gray Street between 9am and 6pm for five days, from Monday June 17.
The alternative route to Killin will take drivers via Crieff and Aberfeldy, before they double back along Loch Tay to the Stirlingshire village.
A council spokeswoman said the road scheduled for repairs is “in poor condition” and “requires attention”.
Dougie Petrie, who runs News First on Main Street, said: “It’s going to close off the whole village at the height of tourist season. It’s absolutely ridiculous.
“People won’t be able to get in at all. A lot of businesses are up in arms about it. It will be catastrophic for trade.
“The more I think about it, the angrier I get. Whoever thinks it’s acceptable to isolate an entire village for a week is an absolute idiot. It’s atrocious.”
Myra Patterson’s Capercaillie Restaurant attracts dozens of diners every day, but she’s worried coach parties will bypass Killin because the road is closed.
“It will affect my business pretty dramatically,” she said. “I’ll probably lose about £5,000. I’ll probably have to half my staffing levels. Our delivery guys won’t get in, either, unless they do a 60-mile detour.”
Bridge of Lochay Hotel owner Bob Stevenson expects bookings to be cancelled.
He explained: “We have guests who will arrive during the day, so they won’t be able to get to us. We will have to contact all of our guests to inform them and I would expect some of them to cancel rooms.
“We also get passing trade and that will stop.”
Danni Grant runs four shops in the village, including a florist and pet shop. Her husband is also the local plumber.
“It’s absolutely ridiculous and will be detrimental to every business in the village,” she said. “But it’s not just about money it could put lives at risk. How will doctors, nurses and carers get in?
“What if my husband is called out to an emergency? How will he get there?”
Many business owners claim Stirling Council failed to consult them before scheduling the work, though the local authority insists that it informed the village community council in April.
Danni Grant said: “The council say it can’t be done at night because it’s too noisy, but I think if we were asked we would have put up with the noise for a few days in order to keep the village open but there was no consultation about this.”
Dougie Petrie added: “They never gave us much of a warning. We only found out when they stuck up signs. We have emailed all our councillors and the MSPs and MP. We’ve asked them to postpone this.”
A Stirling Council spokeswoman said the resurfacing will go ahead as planned and the road must close because the equipment to be used by contractors is too wide.
She also insisted that the work can’t be done at night “because of the close proximity of residential properties”.
She added: “Resurfacing works are programmed throughout the late spring, summer and early autumn period, as this is the most suitable time of the year for laying bituminous materials.
“Because this, unfortunately, coincides with the busiest tourist season, the service seeks to carry out the majority of resurfacing schemes at the beginning or end of the tourist season May, June and September.”