The discussion over the routes has rumbled on for almost a decade

The Transport Secretary is due to decide whether that route or the A358 which joins the M5 at Taunton will be the second main route into the region.

Devon County Council and most businesses in the county back the A303 plan. However, there have been fears that neither route will be upgraded.

A decision is not now expected until after Parliament's summer break.

The discussion over which of the two routes should be duelled has rumbled on for almost a decade.

Business and tourism interests in Devon and Cornwall want the A30, because it brings tourist traffic down to Exeter.

In Somerset, they want the A358 chosen because it would favour Taunton.

There have been numerous public consultations, and even a public inquiry.

The A30/A303 dualling scheme through the Blackdown Hills Area of Outstanding Natural Beauty (AONB), which would cost �337.9m, is shorter than dualling the A358 and is favoured by Devon County Council and the South West Regional Assembly.

However, environmentalists want the land around the A30 left as it is.

The county council has calculated that vehicles travelling via the A358 and M5 would cover an extra 32.8m miles a year.

But Friends of the Earth say that an increase in carbon dioxide emissions is a price worth paying to protect the ancient landscape of the Blackdown Hills.

The dualling decision is not expected to be made until October.