|maint = National Highways

|counties = Hampshire, Wiltshire, Dorset, Somerset, Devon

| terminus_a= Basingstoke

| destinations= Andover<br>Salisbury<br>Warminster<br>Yeovil

| terminus_b= Honiton

| junction=

|

The A303 is a trunk road in southern England, running between Basingstoke in Hampshire and Honiton in Devon via Stonehenge. Connecting the M3 and the A30, it is part of one of the main routes from London to Devon and Cornwall. It is a primary A road throughout its length, passing through five counties.

The road has evolved from historical routes, some of which are thousands of years old, including the Harrow Way and the Fosse Way. The modern route was first laid out in the early 19th century as the New Direct Road, a faster coaching route from London to Exeter. It was initially in demand but fell into disuse as railways became popular from the 1840s onwards. It was not thought of as a significant through route when roads were initially numbered, but was revived as a major road in 1933, eventually becoming a trunk road in 1958. Since then, the A303 has gradually been upgraded to modern standards, though there are still several unimproved parts with longstanding plans to fix them.

As a primary route to southwestern England, the A303 is frequently congested on its single carriageway sections. It passes through the Stonehenge World Heritage Site and the Blackdown Hills Area of Outstanding Natural Beauty, and attempts to upgrade the road in those areas have been controversial. In particular, the Stonehenge tunnel, which would see the A303 rerouted underground, has been proposed and delayed several times. Nevertheless, the road remains a popular alternative to motorway driving.

Route

thumb|left|Part of [[Stonehenge, with the A303 in the background]]

The A303 is about long. The presence of the road through a World Heritage Site has been controversial for decades. As part of a long-term strategy to restore a natural landscape around Stonehenge, the A344 road which once joined the A303 at Stonehenge has been removed, following the removal of other features over the last century including the Stonehenge Aerodrome which used to span the A303 around west of the henge.

After Winterbourne Stoke the route once again becomes dual carriageway from Yarnbury Castle and across the Wylye valley, meeting the A36 at Deptford. There is then another section of single carriageway road, coming out of the valley and up to the crest of the Great Ridge, before a further section of dual down from the hill crest near Berwick St Leonard. On reaching the valley, it reverts again to single carriageway through the village of Chicklade, before following the terrain over to Mere, where it runs north of the town as another dual carriageway bypass. Continuing west, it passes south of Wincanton, then north of Sparkford before bypassing Ilchester and RNAS Yeovilton. Between Ilchester and Shores Bridge (over the River Parrett, east of South Petherton) the road follows the course of the Roman Fosse Way. At Yeovilton the road connects with the A37 which joins it until it reaches the end of the bypass. The dual carriageway ends at South Petherton. It runs north of Ilminster as a three-lane single carriageway where it meets the A358, providing access to the M5 motorway. The road ends joining the A30 at the Devonshire Inn junction. Devon County Council has stated the road is about 60% of a modern standard, while the remainder is unimproved.

The A303 roughly parallels the route of the West of England line, a railway line also connecting London with Honiton. Although the A303 as a whole is designed to be part of a route from London to Exeter, a popular alternative is to take the M4 motorway to Bristol, followed by the M5. This is a high-quality motorway route throughout, but a considerably longer distance.

History

Early history

Parts of the A303, such as the section past Stonehenge, have been a right of way for people, wagons, and later motor vehicles for millennia. Portions of it follow the Harrow Way, an ancient trackway across Wessex that is one of Britain's oldest roads, reportedly being used as long ago as 3,000 BC. Other sections run on part of the Fosse Way, a Roman road between Exeter and Lincoln constructed around 49 AD.

A section of the A303 around Weyhill, west of Andover, runs alongside a ditch thought to be constructed during the Bronze Age. Several historic roads converged at Weyhill, which is believed to have hosted a popular market since the Middle Ages, eventually becoming one of the most important in England by the 19th century. The market closed in the 1950s.

19th century

The modern course of the A303 was designed in the early 19th century as the "New Direct Road" by William Hanning, chief engineer of the Ilminster Turnpike Trust, in order to improve coaching traffic to southwest England. Russells of Exeter began a coach service along it, though they quickly reverted to the older coaching route further south (now part of the A30). Along with engineer Goldsworthy Gurney, Hanning attempted to design a steam-powered coach that could be run along the New Direct Road. After an experimental round trip to Bath, he invested £10,000 in steam carriages. Sir Charles Dance bought three carriages for trips between Cheltenham and Gloucester, but traditional horse-operated stagecoach operators sabotaged the route and Hanning's carriages did not gain widespread adoption. Nevertheless, the New Direct Road became increasingly used as a coaching route between London and Exeter in the 1820s. Ann Nelson's "Exeter Telegraph", a coach from London to Devon via the New Direct Road, could travel from Piccadilly to Devonport in a little over 21 hours. It remained a popular coaching route until the arrival of railways in the 1840s.

The widespread adoption of railways during railway mania caused coaching services to dry up. Along with many other turnpike routes, the New Direct Road fell into disrepair during the 19th century owing to a lack of funds and available staff. By the turn of the 20th century, it had become little more than a rough track in places, making it difficult to drive on.

20th century

thumb|left|The A303 near Stonehenge c.1930. Sign reads "Fork left for Exeter". The houses and [[The Automobile Association#History|AA phone box have since been demolished. The road to the right was the A344. ]]

Road designations were first allocated by the Ministry of Transport in the early 1920s, but the New Direct Road was not initially considered a major through route. Instead, the older coaching road further south via Salisbury and Yeovil was determined to be the main road.

In 1958, the Ministry of Transport upgraded the A303 to trunk road status. It believed it was easier to upgrade than the parallel A30 as it passed through fewer towns. Initial improvements to the road in the 1960s included widening small sections to three lanes (forming the so-called suicide lane) or to dual carriageway; but none were longer than . Andover and Amesbury were bypassed in 1969, while general improvements to the road, including additional dualling, took place throughout the 1970s.

thumb|right|Parts of the A303 were upgraded to [[dual carriageway throughout the late 20th century.]]

In 1971, the Environment Secretary, Peter Walker announced the entire length of the A303 would be upgraded as part of a new roads programme that would deliver 1,000 new miles of motorway by 1980. Bypasses were built, such as the one at Wylye in July 1975. A bypass of Marsh, Devon was opened in 1976; it was (and remains) the only dual carriageway upgrade of the A303 through the Blackdown Hills. The section between Wincanton and Holton opened in stages throughout 1977, costing £3m.

By the mid-1980s, the A303 had been extended from its original fork by Micheldever Station, next to the A30, eastwards to meet the M3 motorway, and was an uninterrupted dual carriageway westwards as far as Amesbury. A bypass of Ilminster had been planned since 1976, but by 1982 the Transport Secretary David Howell had rejected the original dual carriageway plans, calling them "'a waste of money". The new road was built as single carriageway with three lanes, which caused a serious safety hazard leading to several fatal accidents. A bypass of Sparkford was opened on 25 October 1989 by Robert Atkins (politician), while an upgrade to the South Petherton to Ilchester section was opened by Christopher Chope on 13 December 1990.

21st century

<!-- This is the 'History' section. For proposals that have not yet happened, or in active construction, see the 'Future' section below. -->

In 2013, after decades of debate, the A303's junction with the A344, just east of Stonehenge, was closed as part of improvements to visitor facilities. During this work, a roadside monument was moved to the visitor centre; the stone monument is to Captain Eustace Loraine and Staff-Sergeant Richard Wilson, killed in July 1912 in the first fatal accident of the recently formed Royal Flying Corps.

Plans to improve the A303 between Sparkford and Ilchester by upgrading three miles of single carriageway to high-quality dual carriageway were approved by the government in February 2021. Work began on this section that October, and the scheme opened in November 2024.

<!-- This is the 'History' section. For proposals that have not yet happened, or in active construction, see the 'Future' section below. -->

Traffic

thumb|left|220px|Traffic and congestion is a regular problem along the A303, particularly near Stonehenge.

Since the 1950s, the A303 has been criticised for being inadequate for the level of traffic along it. In 1959, it was reported that a typical queue for holiday traffic along the road could be as much as . , over of the road west of Amesbury remains single carriageway, interrupted by various sections of dual carriageway.

In 2017, Devon County Council criticised the section through the Blackdown Hills, as it did not meet modern traffic standards. Particular criticism was directed at steep gradients, narrow lanes and sharp turns, which contribute to lower average traffic speeds, and a lack of lay-bys and verges that cause significant congestion in the event of a vehicle breakdown. The report also noted that a significant proportion of weekday traffic was on business (37%, while the typical figure was 7%), but with a much larger traffic flow on weekends.

The A303 is particularly congested during the Summer solstice (around 21 June) when Stonehenge forms a major part of festivities. On 1 June 1985 (the "Battle of Stonehenge"), a roadblock was placed in the local area. In 1988 a van overturned on the A303 after leaving a clash with police at Stonehenge, killing one passenger and injuring ten others. The A303 is also part of one of the main routes from London to the Glastonbury Festival. During the weekend of the festival in late June, the road is generally gridlocked as people drive towards or away from the festival grounds in Pilton, Somerset.

A Road Investment Strategy published by the UK government in 2014 committed to upgrading all the remaining single-carriageway sections of the A303 as far as Ilminster. Highways England have made numerous proposals to improve the road, and in 2016 it was identified under several Nationally Significant Infrastructure Projects.

Future

Stonehenge area

thumb|After years of deliberation, the [[A344 road (England)|A344 junction with the A303 by Stonehenge was closed and returned to nature.]]

The most controversial upgrade of the A303 has been improvement to the road through the Stonehenge World Heritage Site, where it remains a congested single carriageway road. There were minor changes in the 1960s, including closing the road for a month in 1967 for levelling and resurfacing. A proposal to fully dual the A303 past Stonehenge was announced in the mid-1970s, but was criticised as being "an environmental disaster" and comparable to driving a dual carriageway through Westminster Abbey. A more comprehensive solution was discussed in 1989's Roads for Prosperity programme, which included upgrading the road to dual carriageway and bypassing Winterborne Stoke. In 1993, the Minister for Roads, Kenneth Carlisle, announced plans for either a tunnel or a diversion of the A303 a mile from Stonehenge, costing £44 million and £22 million respectively. Although the new Labour government cancelled many road schemes after coming to power in 1997, there was still general support for a tunnel at Stonehenge.