Wichelstowe southern access scheme
Wichelstowe southern access questions and answers
Find out why the access road and underpass were built, how we chose the design and how the project protects local wildlife.
Why the access road was needed
The new access road was required as part of the planning permission for the wider Wichelstowe site. It was needed to complete the development.
The development includes 4,500 new homes. The access road will divert some additional traffic away from Junction 16.
This will help reduce congestion at the junction and in other parts of the town.
How we chose the design
We considered several factors when choosing the preferred design, including:
- construction costs and risks
- effects on transport
- effects on the environment
- visual impact
- the construction programme
- value for money
Why we built an underpass
At this location, the M4 is higher than the surrounding fields.
Building an underpass caused less disruption than raising the approach road and building a bridge over the motorway.
We built the underpass in phases to keep disruption to motorway traffic to a minimum.
Where the construction materials came from
We reused soil removed from the site during construction of the haul road.
We also brought in soil from other Griffiths projects in the South West. Stone came from the Tarmac quarry at Stancombe, near Bristol.
Griffiths is part of the Tarmac Group. Stancombe is the group’s regional headquarters.
Protecting the environment and wildlife
We created and improved habitats around the site to protect wildlife and support future growth.
We planted trees and seeded the noise bunds. These are small mounds that help reduce noise. We also planted new hedges.
The tree and hedgerow planting will:
- improve important wildlife corridors
- support the natural regeneration of scrub and woodland
- create groups of oak trees around the road
We broke up old roads that were no longer in use so the land could rewild naturally.
Western wildlife receptor site
We created the Western receptor site before construction started. It provides a new habitat for wildlife moved from the construction area.
The new habitat includes:
- tussocky grassland
- new woodland
- hedgerows
- three new ecology ponds
We moved the following wildlife to the site:
- 40 great crested newts
- 670 slowworms
- 13 grass snakes
- 559 toads
Ponds and wildlife underpasses
We aligned two existing ponds and four new ecology ponds on both sides of the road.
This helps wildlife move between habitats using the ecology underpasses.
Measures that help wildlife move around the site safely include:
- wildlife-sensitive lighting for nocturnal animals, including bats, badgers and otters
- tree canopy ‘hop-overs’ that encourage bats to cross the road in line with the hedgerows
- two ecology underpasses for badgers, amphibians, reptiles, water voles and otters
- wildlife kerbs and swales that reduce the risk of amphibians becoming trapped in the drainage system or on the road
- new bat roost boxes in trees
Throughout the project, we compared wildlife surveys completed before and during construction.
This helped us check the success of the rewilding work and the protection of local wildlife.
Walking and cycling through the underpass
The new access road will include a route for people walking and cycling.
It will connect Wharf Road and Hay Lane through the underpass below the M4.
A canal culvert will be built under the realigned section of Wharf Road.
The Wiltshire and Berkshire Canal Trust will complete and connect it at a later date.