A solution to secure the slopes above the stricken Beaminster Tunnel at a cost of £2.1 million has been agreed by Dorset County Council.
The tunnel has been closed since July when heavy rainfall loosened soil above the tunnel and a mudslide trapped and killed two people.
Rosemary Snell, 67, of Misterton and Michael Rolfe, 72, of Fivehead, died when their car was buried by the landslide that left the slopes around the tunnel prone to further disasters.
Engineers have since been working on finding a solution to stabilise the land.
Following their suggestions, the county council’s cabinet decided last week that “soil nailing” would be the best solution for preventing future landslides.
The soil nails would work to pin the slopes together and act as anchors for a mesh that covers the surface.
The masonry headwalls above the tunnel will also be strengthened with new reinforced concrete walls behind them, and new drainage will be installed to redirect rainwater and drain the slopes.
Councillor Rebecca Knox, county council division member for Beaminster, said: “I’m pleased that plans are now moving on with Beaminster Tunnel.
“In recent days it has become clear that securing the soil above the site is the best and safest option.
“The issue now is getting the tunnel opened as quickly as possible.
“The effects of the tunnel being closed have been felt not only in Beaminster but also in surrounding areas.”
Groundwork will now take place to prepare the site – although planning permission will need to be sought before work to stabilise the land can start. If the proposals go ahead it is estimated work will start in the new year and take around five months to complete – costing around £2.1million.
The county council has agreed to fund the work, but will continue to press for exceptional funding from central government. The Department for Transport has refused to provide specific funding for the tunnel repairs.
Councillor Peter Finney, cabinet member for highways and transportation, said: “I’m pleased that we have now got a plan for works to allow Beaminster Tunnel to be reopened.
“This has been an extremely complicated problem for engineers and a lot of work has gone into assessing the land and suitable solutions. We are keen to get the road open as soon as possible, but safety is our overall concern.
“This solution is the best in terms of keeping people safe and keeping the original features of the tunnel and has the least detrimental impact on the visual landscape.”