A concrete extension could be built around Beaminster tunnel in an effort to reopen a main route into the town.
Rosemary Snell of Misterton and Michael Rolfe of Fivehead died when their car was buried under a landslip at the tunnel in July.
They were entombed for more than a week before their bodies were found.
The tunnel has been closed since the landslide as engineers at Dorset County Council draw up schemes to reopen the route.
Traders in Beaminster say the tunnel's closure has wiped out passing trade in the town.
This month engineers put forward five possible solutions including stabilising nearby slopes, permanently extending the tunnel, removing soil from the hillside above the tunnel, removing the tunnel completely and building a cutting, or bypassing around the tunnel.
A meeting was held last week to explain the ideas to local people.
More details have emerged on the option of a permanent concrete extension to the tunnel.
The structure would span the existing tunnel opening and side walls on the approaches, preserving the historic tunnel.
A council spokesman said: "From our point of view, it was a really useful meeting. It was good to hear feedback from local people and to be able to present the possible solutions."
Councillors have asked engineers to develop in more detail plans to stabilise the slope.
The route will remain closed off until 2013, no matter which option is chosen.
A report on tests around the tunnel is due next month.
The spokesman said: "Early results, using typical sand properties, indicate that the retaining walls are unacceptably weak. This is unlikely to change when the full test results are available.
"Engineers need the full test results before they can decide whether stabilising the slopes is feasible and how far that stabilisation would need to extend.
"Either option will take an estimated six months to build. Detailed design, identifying and appointing sub-contractors and gaining consents will add to the time.
"The formal road closure notice will therefore be extended until the end of June 2013."
