Glencoe ski resort. Photo: Flossiesheep CC-BY-SA-3.0

A planned 14-week closure of the main road alongside Loch Lomond to the Highlands could sound the death knell for the recovering Scottish winter sports industry.

The Scottish Government has approved the building of a viaduct to carry the A82 trunk road at Pulpit Rock, between Tarbet and Crianlarich.

The narrow section of the busy road to many Highland walking, climbing and skiing venues is a notorious bottleneck with traffic lights allowing only alternate one-way traffic, with resulting long queues at peak tourist times.

The road carries a large amount of traffic between Glasgow and Fort William, from large goods vehicles and tourist coaches to numerous cars carrying outdoors enthusiasts to the mountains of the western Highlands.

But the work will mean a total closure of the route for three months, with a diversion via Rest and Be Thankful and Inveraray before returning to Tyndrum via Dalmally and the A85. The alternative route will add 30 miles (48km) to the journey. It is estimated the journey will take at least an hour longer.

Skiing experts have urged planners to put the works back to the late autumn. The road closure is currently scheduled to begin in January 2012 and to be in force until April – covering the peak period for skiing and winter climbing and hillwalking.

With daylight hours at a premium for those venturing on to the hills in winter, a delay of an extra 60 minutes could be crucial in making a trip viable or not.

Snowsport Scotland, the national governing body for skiing and snowboarding said: “It will be near enough equidistant from Glasgow to Glenshee, Cairngorm and Glencoe and further to Nevis Range: so a very early start to all day trips and potentially a devastating outcome for the financial viability of Glencoe Mountain Resort.”

A consultation by Transport Scotland ended yesterday, and the results are awaited before a final decision on the timing of the closure is made. One reason for the winter closure is to minimise wildlife disruption, particularly to otters and bats in the area. The road planners intend to install artificial otter holts and bat roosting locations.

In addition to the 14-week closure, the roadworks necessary for the improvement, which will see a 180m viaduct constructed to carry traffic over the waters at the northern end of Loch Lomond will need a realignment of the road over 400m and a speed limit of 20mph or 30mph will be imposed during this work. Delays are inevitable, and the whole project is likely to run to 12 months.

In February this year, the Glencoe ski resort, on the northern slopes of Meall a’ Bhùiridh, was the snowiest in the world, with a 24-hour snowfall of 80cm – more than any other ski slopes worldwide at the time.

Scottish ski resorts had their best season in decades last winter, with some reporting skiing right into June. But poor snowfalls in previous years had left many resorts in a parlous financial state, with new owners taking over the Glencoe ski centre last winter.

• The ‘temporary’ traffic lights at Pulpit Rock, on the most winding section of the lochside road, celebrated their 30th birthday recently and gained a brief unofficial adornment of balloons to celebrate the occasion.

Nearby Pulpit Rock was excavated under the direction of the Rev Peter Proudfoot in the mid 19th century and was a meeting place for Free Church congregations until a church was built at Ardlui. It is protected as a scheduled ancient monument.