Expressway to the South West

Highways England have long-term plans to create a continuous expressway route to South West England from London along the A303 and A358, incorporating existing dual carriageway sections and building new ones to link them. The finished route will run from the M3 at junction 8 south-west of Basingstoke to the M5 at Taunton.

The existing sections of dual carriageway on the A303, most of which are already at a very high standard, are evidence that this is not the first time there have been aspirations to create a continuous high speed road on this corridor. Plans existed in the 1970s, in which era discussions in Parliament allude to a planned completion by the 1980s. In the late 1980s and early 1990s there was renewed interest, with new sections being built, but again the route went unfinished and progress came to a halt. There are two factors behind this.

The first is the traffic on the road, both current and projected: the A303 in particular is a very rural road, passing few towns of any significant size, and carries a lot of seasonal holiday traffic which isn't always easy to account for in official figures. If the Government of the day is not predisposed to roadbuilding this makes it one of the easiest places to cancel road schemes as its improvement schemes typically end up with a lower Benefit Cost Ratio than others elsewhere.

The second reason progress has kept stalling for the last 40 years is Stonehenge, which sits right alongside the A303 near Amesbury in the midst of a unique landscape of prehistoric monuments and Army firing ranges. Any improvement here has to be sensitive to the World Heritage Site it passes through.

For the last fifteen years or so, the preferred solution has been to bury the A303 in a long tunnel that will keep traffic out of sight of the stones and avoid damaging the ancient landscape, but the expense of such a project can barely be justified for the traffic on the route and so it has bobbed in and out of the list of trunk road schemes like a rubber duck in a storm. Without a solution at Stonehenge, the argument goes, there is little point improving the rest of the road, and so all other improvements hang upon it.

Highways England now think they finally have a way to build a tunnel long enough to appease English Heritage and their partners while keeping the costs low enough that the scheme will finally happen, and on that basis they are now promoting some other schemes elsewhere on the route.

These include dualling the A358 from the A303 to the M5, which is being done to complete the expressway at its western end instead of the original plan (and perhaps the more obvious choice from looking at a map) to dual the next section of A303 from there to the existing expressway A30 at Honiton. The A303 passes through the Blackdown Hills, an Area of Outstanding Natural Beauty, and the A358 is much busier, so the current plan is more pragmatic even if it is not guaranteed to provide the fastest route to Exeter. If it does at least deliver a dual carriageway all the way from the M3 to the M5 the pragmatism will at least pay off, because until now finishing the job has proven remarkably difficult.