The A303 must be one of Britain's most important three-digit roads. It forms the central section of the trunk route from London to south-west England, the rest being covered by the M3 and A30. Unusually, the A30 runs parallel to it for almost its entire length as a non-primary route, a legacy of the fact that the A30 was the trunk route until April 1, 1958, when an order made under the 1946 Trunk Road Act transferred this status to the A303. Despite that, primary route status remained on the A30 as well until the 1980s. It must also be a candidate for longest distance between signposted destinations in England: Andover (Hants) to Honiton (Devon) is over 80 miles. Large sections of the road are continuous dual carriageway, but there are still several sections of single carriageway which can regularly create bottlenecks along this popular route for holiday traffic.
Over time the A303 has been gradually upgraded at the expense of the A30, to the extent that some now think that it should bear the A30 number. However, this renumbering is unlikely to take place: the number has become so familiar that it even became the title of a song by Kula Shaker, written after a trip to the Glastonbury Festival.
Popham Interchange - Mere
The initial two miles or so is in fact a renumbered A30, leading directly from the spur of the M3 at junction 8, creating what is sometimes known as a 'useless multiplex'. At the next junction near Micheldever Station, the former A30 (now unclassified) leaves. The next main junction is with the A34 and rerouted A30 at Bullington Cross, which is strangely shaped to avoid the former pub of that name which was situated there, but which has now been demolished. The next section of dual carriageway is the oldest dual stretch on the route, but has been integrated into the modern road. It runs across the River Test and through Harewood Forest to a trumpet junction with the A3093 on the eastern outskirts of Andover, where it joins onto the Andover bypass, opened Sept 11 1969 – the rather old-fashioned junction with the A3057 being an indication of the pedigree of this road. There is then a trumpet junction with the A343 and a dumbbell junction with the A342 – a section of the A342 through Weyhill in fact being part of the original route of the road prior to the construction of the Weyhill bypass in the 1980s.
The dual carriageway continues past the airfield and motor-racing circuit at Thruxton, and on to another older-style junction with the A338 despite this only dating from 1988. It passes Bulford camp, where the A3028 leaves (or rather arrives - it's one-way towards the A303), and then comes to a much older section of dual carriageway – the 1960s Amesbury bypass. Here we meet our first roundabout – the Countess roundabout meeting the A345 , which is notorious for queues. Shortly after this the road narrows to single carriageway, for reasons that will immediately become obvious.
The road bears to the left at Stonehenge Bottom, where the now-closed A344 bore off to the right, and then runs close to Stonehenge itself. The issue of what to do about a major arterial route passing so close to an ancient monument has caused problems for many years. The most recent plans were to build a tunnel bypassing the current route just to the south, which would give uninterrupted pedestrian access to the stones, but various political wrangles mean that little progress has been made. So traffic is slowed down fairly drastically along the next section, which meets the A360 at a roundabout (Longbarrow crossroads), and then passes through the village of Winterbourne Stoke. The Stonehenge tunnel plan also incorporates a bypass of Winterbourne Stoke, and grade-separated junctions with the A345 and A360. After this the road resumes as dual-carriageway through a cutting near Yarnbury Castle, leading to a very odd junction with the A36 at Deptford, on the River Wylye – you'll see that although there's complete access in all directions, the junction layout is messy and even requires a gap in the central reservation of the A36!
This section of dual carriageway doesn't last for long, but nor does the next section of single carriageway past Stockton Wood. Another short section of dual carriageway skirts the Great Ridge, but then the road returns to single carriageway through the village of Chicklade – again, I don't know what the villagers have to say about this. There then follows what must be one of the simplest multi-level junctions in the country: the A350 crosses beneath the A303, and a single two-way 'slip road' turns right off the A303 to join the two! This junction may be the oldest crossroads in the world as it forms the intersection between the ancient Harroway, which the A303 follows, and the ancient Ridgeway which the A350 here follows.
Mere - Upottery
Another long section of dual carriageway starts on the outskirts of Mere. (Mere, Wincanton and Sparkford all originally had separate bypasses, but they were eventually joined together to create another 'sub-motorway' route.) This road also bypasses the villages of Zeals and Bourton, continuing to the Somerset town of Wincanton, where a single trumpet junction gives access to all the local roads as well as the A371 and A357. The road runs close to Cadbury Castle, with the dual-carriageway section ending on a roundabout meeting the A359 west of Sparkford. About a mile past here the original road branches off to the left as the B3151, serving the Royal Naval Air Service station at Yeovilton (which includes the Fleet Air Arm Museum). The road runs for a short distance along the original A372 , then a dual-carriageway section bypasses Podimore to lead to a large roundabout, which appears to have provision for the A303 to run underneath if required. This meets the A372 and a slightly re-routed A37 to Bristol.
The next section is the Ilchester bypass. The old A303/A37 junction at Ilchester was notorious for traffic jams, and I well remember the relief when this road was opened. It curves round through a cutting to cross the River Yeo, after which the southbound A37 to Yeovil leaves at a trumpet junction. The dual carriageway continues after the end of the bypass along a straight Roman road, the Lincoln to Devon Fosse Way, passing close to the gardens at Tintinhull. The flow is interrupted slightly by a roundabout at the junction with the A3088, then the road continues motorway-style to a roundabout near South Petherton.
This is the start of the Ilminster bypass, which was built a single-carriageway without provision for upgrade to dual, so it hasn't been dualled since, making the road rather dangerous in my opinion, although there appear to be plans for an upgrade now. This rather wide single carriageway passes through cuttings and under bridges to a roundabout at Horton Cross where it meets the A358, then bypasses Horton village. The road continues along its original course to the Somerset/Devon border, where there is a very short section of dual carriageway bypassing the village of Marsh, after which there is a remarkably sharp left-hand bend for a trunk road. The final section of single carriageway passes through Newcott, before meeting the A30 at a classic TOTSO junction: the non-primary A30 joins from the left, and the trunk A30 continues on towards Honiton as though it were the same road – which, in an obvious sense, it is. The TOTSO is a legacy of the turnpike age when, in the early 19th century, the route of the A303 west of Andover was rebuilt as the "New Direct Road" to Exeter.
Original Author(s): Guy Barry & Paul Rowntree