The A465 Heads of the Valleys Road is shut between Glynneath and Hirwaun after what authorities are describing as a “serious collision.”
The incident has led to significant travel disruption across the region, with the route serving as a key corridor between south Wales, mid Wales, and the Midlands.
Traffic Wales has advised drivers to avoid the area and seek alternative routes, stating that the road is likely to remain closed for some time.
Gwent drivers, whose westbound journeys frequently rely on the A465, are among those most affected.
The closure impacts a busy section of the road that connects the Vale of Neath to Hirwaun and feeds into the dual carriageway leading towards Dowlais Top and Merthyr Tydfil.
From there, the A465 continues through Blaenau Gwent and on towards Abergavenny, forming the main east–west link between the heads of multiple south Wales valleys.
For Ebbw Vale, Brynmawr, and Abergavenny residents, the route offers a direct, toll-free alternative to the M4 when travelling to Neath, Swansea, and further west.
A full closure in this area means all westbound traffic from Gwent is currently being diverted, with the risk of heavy congestion on surrounding roads as drivers seek alternative routes.
The incident is also impacting drivers in areas such as the Vale of Glamorgan, particularly those who access the A470 and A465 via Merthyr Tydfil for regular journeys to mid Wales, the Midlands, or Swansea.
Traffic Wales South said: “Road closed due to collision.
“Emergency services at scene. Please find alternative route.”
The road is expected to be closed for some time. Drivers should find alternative routes.
For longer-distance travel from Gwent to Swansea or the west, the M4 remains a more reliable option during the closure, even though it adds to the journey distance.
Near the incident, possible diversions include using the A4059 around Hirwaun and Llwydcoed or looping from Neath via the B4242 and other connecting roads.
However, these routes are narrower and slower, and authorities recommend them only for local traffic or those already in the immediate area.
Longer-distance travellers are advised to avoid the area until the A465 has fully reopened.
Traffic Wales South have been contacted for details.
