Options for a new route to replace a landslip-prone section of the A83 include building up to three bridges or tunnels.
Transport Scotland published details of the 11 “corridor options” on Wednesday as the Rest and Be Thankful in Argyll reopened under traffic light control after being blocked by two major landslides within six weeks.
Building new fixed link crossings at Loch Long, Gare Loch and the Firth of Clyde are among the options, which also include building a new road in the glen behind the current route.
Others include new crossings from near West Kilbride, North Ayrshire, to Bute via Little Cumbrae, and further crossings either over the Firth of Clyde from Rothesay to Toward, or from Rhubodach to Colintraive.
The public are being asked to give their views on the various routes in a consultation which ends on October 30.
Transport Secretary Michael Matheson said: “Following the recent landslips at the A83 Rest and Be Thankful, I understand the frustration and disruption that these bring for local communities and road users.
“While our previous and ongoing investment in catch pits has helped keep the road open for an estimated 48 days when it would otherwise have closed, I realise people are looking for a long-term solution to dealing with landslips at the site and we are committed to delivering one.
“Transport Scotland is now taking forward the project development and assessment work required to deliver an alternative infrastructure solution to the existing A83, in parallel with the second Strategic Transport Projects Review.
“We are committed to placing public engagement and meaningful dialogue with directly affected communities and other stakeholders at the heart of the development and delivery of our plans for improving the route. We want to ensure that communities have the opportunity to comment on the proposals for the scheme at every stage in the process.
“From today we are launching a new website for the design work and the 11 corridor options under consideration can be viewed there. Please visit the site and give us your input by October 30.”
The preferred route corridor is expected to be chosen by spring 2021.
Mr Matheson added: “We recognise that the timescales for an alternative to the current route are frustrating for the local community but in recognition of the pressures the current situation brings, we remain committed to progressing substantial shorter term investment in the existing A83 in tandem with the work to identify a permanent solution as part of a two-phased approach.”
One lane of the road opened at around 7.35am on Wednesday after repairs required when heavy rain on September 13 brought down around 7,000 tonnes of debris.
Prior to this closure it had been open for under a week having been blocked since a major landslide on August 4.
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