A360 Closure – Community Q&A

Why is the A360 being partially closed?

The road is being closed to allow electricity and fibre optic cables to be laid for the A303 Stonehenge project, which needs an electricity supply for construction, and for the tunnel once built.

Who is undertaking the work?

Scottish and Southern Electricity Networks (SSEN), operating under their own statutory powers, will be undertaking the work on behalf of Highways England along with their contractor Instalcom. 

Can the fibre optics being laid by SSEN be used by the residents and businesses to boost their broadband speeds?

The fibre optics that SSEN are laying will be used to control the networks systems and security infrastructure. It will only be connected to their internal systems and so can’t be used for commercial broadband connections.

What do the works consist of?

Two high voltage cables and a fibre optic cable are being laid from the Salisbury Grid substation (close to Quidhampton Quarry between Wilton and Salisbury) and the Longbarrow junction between the A360 and A303. The work will be starting from the south and progressing north. 


The Salisbury grid substation is the only local substation with sufficient capacity without requiring a significant upgrade to be able to meet the required power requirements. 


A temporary new substation will be built next to the construction compound to supply the power during construction works. 


When the tunnel and new A303 is built, this temporary substation will be removed along with the construction compound, and the cable rerouted to the tunnel entrance to provide permanent power for the tunnel.

Why does the project require a completely new electricity supply?

The project needs a large power supply for the tunnelling equipment and to run safety equipment for the tunnel when it is open. There is not a large enough supply in the area, so a new high voltage supply is needed. 

Why does the road need to be shut completely?

A single lane closure was also considered, but the narrow width and nature of the road with minimal verges on the A360 raised significant safety concerns for drivers and those working on the site. As safety of the travelling public and its workforce is a key priority for SSEN, Highways England and Wiltshire Council, this solution was deemed unacceptable. Following consultation with Wiltshire Council and Highways England SSEN determined that a full road closure would provide the safest and quickest solution.

When will the road be closed?

The A360 will be closed for approximately 3 months between the beginning of September and December, they are aiming to finish before the 3 months

What section of the A360 is being closed?

The A360 will be temporarily closed to the south of the A303 between Longbarrow roundabout (A360/A303 junction) and the Avenue roundabout – a distance of approximately 5.3 miles

A360 road closure map

What is the diversion route?

Traffic will be diverted via the A345, and part of the A303 and A36. Diversion routes will be marked by road signs. 


In addition to the diversion route signs, they are putting up signs that will inform drivers of the closure further afield (including Devizes, Shaftesbury and the routes around to Salisbury) to encourage people to divert earlier while there are other route options.

What measures are being taken to stop people ignoring the diversion route and going through my village (B3083 and Woodfords)?

Weight limits for minor roads will be brought in for the duration of the works to ensure HGVs do not rat-run through inappropriate alternatives. Wiltshire Council is introducing temporary weight restrictions including a 7.5 tonne weight limit on the C42 between Stratford Sub Castle and Stonehenge Road, Amesbury, and the C294 between Stratford Sub Castle and Great Durnford.  These restrictions will have exemptions for either loading or access. Please see the map included for further details on diversion routes and weight restrictions. 


They will actively encourage people not to use the B3083, which includes difficult right hand turns onto the A303, and to use diversion routes.  They will monitor these routes alongside Wiltshire Council and introduce additional measures if needed.

Where will there be increased traffic?

They are expecting additional traffic on the diversion route, and on some local roads - but will be continuously monitoring traffic levels in conjunction with Wiltshire Council and will introduce additional measures if required. 

Will the A360 be open for emergency traffic e.g. ambulances etc?

Emergency access will be maintained for properties along the A360. SSEN will share details of access routes as work progresses with the emergency services.

Why can’t the cables be laid over fields instead of along the road?

SSEN investigated several options as an alternative to the temporary closure of a section of the A360.

Along with feasibility studies, environmental impact studies were undertaken on two options to work on land adjacent to the carriageway. The findings of these studies revealed a considerable impact on the environment which would significantly increase to the cost of the programme. The damage to the environment was unacceptable to both partners and SSEN, who acts as a considerate constructor. 


In addition to this, the off-carriageway option was explored with landowners who were unhappy with this proposal.  As such this option would have required separate Statutory Powers to be obtained and this delivery was unachievable to meet the timescale of the overall A303 project and, as such, had to be discounted.

Will residents have access?

The closed section of the A360 will remain accessible to residents and affected businesses located on or near the A360. This includes deliveries and access for emergency services.

Depending on the progress of the work, and where the cable is being laid, access may need to be restricted to a particular direction or route. Residents will be kept up to date on what’s happening by the contractors. (NB they will be given a special number to ring if any issues, and progress will be posted online).  SSE will liaise regularly with farmers who require access to identify routes and to ensure we can accommodate their movements while progressing the works

Will the businesses located on or near the A360 be affected?

Businesses will remain open. SSE will work with affected businesses to accommodate their needs, access and provide “Business open as usual” signage.

Is this going to disturb local electricity/ broadband/ energy supply?

They don’t anticipate any disturbance because the cables being laid are separate from normal electricity supplies to properties, but if there is a need to interrupt supplies, SSE has a set process in place which goes above the regulatory requirements. They provide written notice to impacted customers giving 7 days’ notice for domestic customers and 30 days for business, where possible (some works may require the statutory minimum of 2 days’ notice.

Will the work be noisy for local residents?

SSEN has a duty of care under construction regulations to manage noise pollution levels and will minimise disruption for residents.

What is Highways England doing to help local residents?

They are already in conversation with Wiltshire Council and will do so with the Police to explore what enforcement measures can be undertaken. They will also discuss what options there are for “local access” signs. 

They have undertaken to monitor traffic behaviour on local roads and the diversion route during the closure and to work with Wiltshire Council to see what additional measures can be taken to resolve issues where possible. 

They say they would like to work with the community to identify issues, and they will hold a special community forum meeting a couple of weeks after the start of these works where they can take on board feedback from residents. 

In addition to this, they are also looking at other ways in which disruption could be minimised, for example reducing the closure duration by working longer hours when it is safe to do so
without endangering the workforce or inconveniencing residents through noise or light pollution.