Drivers in Monmouthshire face significant overnight disruption this March as Welsh Ministers prepare to close Dixton Roundabout overnight for essential works on the A40. The major trunk-road scheme, announced in a forthcoming traffic order, will temporarily shut the entire circulatory carriageway of one of Monmouth’s busiest junctions.

The planned order invokes Section 14 of the Road Traffic Regulation Act 1984 to legally enforce the closure. Officials say the shutdown is required to allow crews to carry out essential works “on or near the A40 trunk road” at the roundabout, though the nature of the upgrade has not yet been detailed. What is clear, however, is that the closure will affect all vehicles—except those being used by emergency services or by contractors working on the site.

The order is scheduled to come into force on March 11, 2026. Once active, the restrictions will operate overnight only, between 8pm and 6am, for approximately one week. The works may finish sooner if progress allows, but the order will remain valid for up to 18 months as a contingency should weather, safety issues or follow‑on works require the closures to be reinstated at a later date.

To keep traffic flowing, an extensive set of diversion routes has been mapped out. For non‑HGV traffic travelling eastbound, the official diversion will send drivers from Raglan Interchange down the A449 to the M4 at Coldra, continuing east to Junction 23, then joining the M48 before routing vehicles north via the A466 at Chepstow, towards Highbeech Roundabout, and onto the A48. From there, motorists will loop to Highnam and rejoin the A40 towards Ross‑on‑Wye before heading back toward Monmouth. The same route applies in reverse for westbound travellers.

A separate diversion is in place for non‑motorway users, taking them south on the A449 to the M4 junction but diverting them onto the A48 before rejoining the main diversion route. Heavy goods vehicles face an even longer detour, being routed along the M4, M5 and M50 before rejoining the A40 near Ross-on-Wye.

Officials warn that, when necessary, the closure will also suspend the right turn from the eastbound A40 onto the A466.

Residents and commuters are being advised to plan ahead, expect longer night‑time journey times, and check for updates, as any changes to the schedule will be announced before work continues.