A 69-year-old local man has been seriously injured in an accident on the Great Western Way this morning.
Police were called to the eastbound carriageway outside B&Q at 9.42am.
A spokesman for Wiltshire Police said: "A 69 year old man has suffered very serious injuries, potentially life threatening, and has been taken to Frenchay Hospital.
"We haven't yet ascertained if the man was on a bike or pushing a bike, as there was a bike near the scene."
Nobody else was injured in the accident, but the van involved was an Iveco Daily 50 white tipper van.
The road has been closed eastbound between Barnfield Road roundabout and Bruce Street Bridges and is set to remain closed for several hours while a police investigation is underway.
Police are advising drivers to seek an alternative route.