The A436 is closed in both directions due to an accident at the A435 Cirencester Road junction.
Congestion is back to the A417 (Air Balloon Roundabout).
Police hope the road will be open by around 6.30pm.
More top news
Heavy showers overnight, hail and thunder possible, humid
Heavy showers overnight, humid, thunder possible
The Maltings shopping centre was closed to the public after a small amount of the Novichok substance was found in the area.