Drivers are being warned of possible delays on the A470 southbound between Pontypridd and Coryton this morning.
Traffic Wales has reported congestion on the busy stretch of road, which is a key commuter route into Cardiff.
Motorists travelling towards the Coryton interchange are advised to allow extra time for their journeys and consider alternative routes where possible.
The A470 is one of the main arterial roads linking the South Wales Valleys with the capital, and even minor disruption can lead to knock on delays during peak travel times.
