Drivers across Wales are bracing for significant disruption as 18 road closures are scheduled on the M4 and major A-roads from Sunday, July 19, 2026. The maintenance work, detailed by Traffic Wales, will affect key routes including the A470 near Pontypridd, the A465 in Neath, and the M4 at Junction 25A, potentially causing delays for summer holiday travellers.
M4 and A470 Closures
The M4 J25A Grove Park eastbound will see a bridge closure for maintenance from July 20 to July 27, operating nightly from 8pm to 6am with a diversion in place. On the A470, multiple closures are set: southbound from Upper Boat to Nantgarw, northbound from Upper Boat to Pontypridd, and southbound from Pontypridd to Upper Boat, all from July 19 to July 20 between 8pm and 6am. Diversions will be clearly signposted.
A465 and A4042 Works
The A465 Resolven to Aberdulais northbound will be closed for resurfacing from July 13 to August 12, nightly 8pm to 6am. Meanwhile, the A4042 sees closures: northbound from Southern End to A4051 interchange and southbound from A4051 interchange to Brynglas, both on July 20 to July 21, with diversions in place.
Extensive A55 Disruptions
The A55 in north Wales faces multiple closures. The J10 Caernarfon Road eastbound onslip is closed for resurfacing from July 3 to July 31, 6.30pm to 6.30am. The eastbound carriageway from J9 Treborth to J11 Llandygai is closed for maintenance from July 5 to July 24. Additionally, the eastbound road at J9 Treborth, J10 Caernarfon Road, and J11 Llandygai are all closed for resurfacing from July 4 to July 31. Diversions are in place for all.
A483 Cyclic Maintenance
The A483 will see a series of overnight closures for cyclic maintenance: at Groesfeol (both directions) on July 19-20 and July 21-22, 7pm to 6am; at Ruthin (both directions) on July 19-20; at Johnstown (both directions) on July 22-23; at Johnstown northbound on July 21-22; and at Ruabon (both directions) on July 22-23. All have diversions in place.
Motorists are advised to plan ahead, allow extra travel time, and follow diversion signs. Traffic Wales urges drivers to stay updated via its website and local travel news.
