Emergency crews were at the A5 Dobbies Roundabout at Meole Brace after the collision happened at around 10am.
The road was clear again by lunchtime but traffic was heavily congested on all approaches to the island, which is where the A5 meets the A49 and A5112 Hereford Road.
West Mercia Police spokeswoman Eleanor Harris said: "There appears to have been a collision between a lorry and a car. We have no further details at this stage."
The AA Traffic News website added: "Partially blocked, accident, very slow traffic, on the roundabout.
"Partially blocked and very slow traffic due to accident on A5 both ways at A49 Hereford Road (Dobbies Island). Police confirm an accident on the island. On the roundabout."
It came as repairs continued on the A49 at nearby Bayston Hill after a manhole collapsed on Tuesday, leading to four-way traffic lights being installed on the junction of Hereford Road and Lyth Hill Road.
Traffic was held up as far back as Emstrey Island on the A5 on Wednesday, while Dobbies Roundabout was also gridlocked.
Motorists have been taking alternatives routes via narrow country lanes which has led to further congestion on nearby roads.
Severn Trent has not yet said when the emergency repairs are likely to be completed.
A spokeswoman said on Wednesday: "The council reported a collapsing/dangerous manhole to us yesterday and it is in close proximity to a BT cover.
"We have had to put the lights up as a safety measure for our crews and members of the public. I'm sorry for any inconvenience caused."