Costain’s new M5 junction 22A: access, capacity and design notes for engineers
Reviewed by Joe Ashwell

First reported on The Construction Index
30 Second Briefing
Costain has secured a £100m, five-year contract under National Highways’ Regional Delivery Partnership to design and build a new M5 junction 22A in Somerset between Burnham-On-Sea and Bridgwater. The junction, with north-facing slip roads, will connect directly to the planned Gravity Smart Campus and Agratas’ £4bn EV battery gigafactory, expected to be the UK’s largest. WSP will act as design partner, with the scheme intended to relieve congestion on the M5 south of the Huntspill river and upgrade strategic access for heavy industrial traffic.
Technical Brief
- Contract value to Costain is approximately £100m over the five-year delivery period.
- Costain acts as delivery integration partner and main works contractor, responsible through to handover.
Our Take
Costain’s £100M role on the new M5 junction in Somerset sits alongside its current heavy civil commitments on HS2 with the Skanska Costain Strabag JV, signalling that the company is maintaining a sizeable exposure to complex UK transport nodes rather than pivoting away from major infrastructure risk.
Linking the M5 directly to Agratas’s £4bn gigafactory at the Gravity Smart Campus effectively turns a private industrial investment into a strategic road scheme, which is likely to strengthen National Highways’ case for future junction upgrades tied to battery and EV supply‑chain hubs elsewhere in the UK.
Within our 549 Infrastructure stories, Costain appears frequently in both highways and rail megaprojects, so this junction 22A award reinforces its positioning as a go‑to contractor for long-duration (five‑year plus) design-and-build frameworks with National Highways and other state-backed clients.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
Related Articles
Related Industries & Products
Construction
Quality control software for construction companies with material testing, batch tracking, and compliance management.
CMRR-io
Streamline coal mine roof stability assessments with our cloud-based CMRR software featuring automated calculations, multi-scenario analysis, and collaborative workflows.
HYDROGEO-io
Comprehensive hydrogeological testing platform for managing, analysing, and reporting on packer tests, lugeon values, and hydraulic conductivity assessments.
GEODB-io
Centralised geotechnical data management solution for storing, accessing, and analysing all your site investigation and material testing data.


