A ‘corridor’ of improvements: upgrading the A303, A358 and the A30

We’re improving the A303, A358 and the A30 as part of a wider plan to improve connections between the south-east and the south-west of England.

Why we're making these improvements

The A303/A358 is a main route, running across the country.    It’s one of two strategic routes into the South West (the other being the M4/M5) and links the M3 in Hampshire and the M5 in Somerset, passing the world-famous Stonehenge monument through the surrounding World Heritage site. Around 26,500 vehicles use it on an average day - and many, many more during the summer months. It’s well known for being an unpredictable route, with accidents and congestion causing delays. To address this, we’re dualling the road in certain places to make it safer and better able to cope with the traffic that uses it. We have one scheme in construction, two in development, and a further project being looked at as part of some early work to potentially feed into the fourth road investment period (2030-2035)

The A358 connects the A303 to the M5 at Taunton. It’s an important part of the jigsaw in improving links between the south-east and south-west, because improvements here will reduce traffic through the Blackdown Hills Area of Outstanding Natural Beauty and make the route between the M5 at Taunton and the A303 more reliable and resilient.

We're also improving the A30 between Chiverton and Carland Cross. This is really important for Cornwall’s future. We’re currently dualling the only remaining stretch of single carriageway on the A30 between Camborne and the M5 at Exeter. It’s designed to fix the problems with congestion that have delayed journeys for decades, leaving traffic at a standstill and hampering the Cornish economy.

Schemes in construction

A303 between Sparkford and Ilchester in Somerset

Features of the scheme:

  • Upgrading to dual carriageway
  • In construction
  • Ongoing until 2024

We’re building a new 3-mile section of dual carriageway. This will start east of Podimore Roundabout and once finished the new route will bypass the existing Hazlegrove Roundabout. The new road is being built away from the existing A303 but it will cross and tie into the existing road in certain places.

Our aim is to keep one lane of traffic on the A303 open in each direction during the works - which is the same as before work started. When it's finished, there will be two lanes in both directions.

During the works, there will be times when we’ll need to close the road overnight, such as when we lift new bridges into place. Some local road arrangements will also change, so it’s important to check how this might affect journeys to tourist destinations.

A303 Sparkford to Ilchester scheme page - latest updates

A30 between Chiverton and Carland Cross in Cornwall

Features of the scheme:

  • Upgrading to dual carriageway
  • In construction
  • Ongoing until 2023-24

We’re building a new 8.7-mile section of dual carriageway. It’s being built away from the existing road, but will tie into the current A30 at Chiverton Cross and Carland Cross roundabouts. These roundabouts are being rebuilt as part of the work. Once finished, they’ll be split level junctions, which means that only traffic leaving or joining the A30 will need to use them.

You’ll probably see some road building activity if you drive along the A30 in Cornwall. We’re doing what we can to keep traffic moving along the route during the works. Our aim is to keep at least one lane of traffic open in each direction during the works – which is the same as before the work started.

Some local road arrangements will change over time, so it’s important to check how journeys you might have made in the past might be affected.

A30 Chiverton to Carland Cross scheme page

Schemes in development

We’re continuing to work on the A358 Taunton to Southfields scheme and the A303 Stonehenge scheme. They’re not in construction yet but you can find out more about what’s happening with them on the links below.

A358 Taunton to Southfields scheme page A303 Stonehenge scheme pages

Pipeline schemes

At the Government’s request we’ve started some early work to look at the section of the A303 between South Petherton and Southfields (in Somerset) to understand what could be done to improve the flow of traffic. 

We’re doing this as part of a pipeline of potential future schemes, which might feed into the fourth road investment period (RIS4), which runs from 2030 to 2035. Between now and 2023, we'll develop options for all the pipeline schemes, engaging with our stakeholders and carrying out more research. This information will help the Department for Transport decide which of these schemes may be selected for delivery as part of RIS4 or future Road Investment Strategies.

All the schemes in the RIS4 Pipeline programme remain uncommitted, with no guarantee they will be taken forward into construction. We won't know which schemes are committed until the RIS4 is published.

Why is it important to improve these roads?

Local councils and business leaders agree that upgrading these roads to dual carriageway will connect the South West better to neighbouring regions, helping the region to grow and supporting plans for more homes and jobs. Watch the videos below to find out why these schemes are important to them.

Visit Somerset 

Peninsula Transport 

Heart of the South West Local Enterprise Partnership 

When will the whole corridor be improved?

In 2014, the government set out its goal to improve the connections between the south east and south west, but delivering it will take some time. Several other points along the A303 / A358 have been highlighted for possible future development. 

Ultimately, the Department for Transport will decide if and when it wishes to progress the remaining schemes and the timelines for these.

These decisions are taken through the Road Investment Strategy, which is the government’s rolling five-year investment strategy for the strategic road network.

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Find out more about each scheme below: