Drivers are being advised to avoid Watton Road and the A47 near Little Melton after a tractor flipped on to its side.
Police were called to the incident at 10.27am, at the top of the A47 sliproad approaching Little Melton.
The incident is believed to have been caused by the tractor colliding with another vehicle.
No injuries have been reported.
The tractor was righted and removed at 12.15pm and the road has reopened, with traffic moving normally.
Bus services have been affected, with the Konect 3 and 6, as well as the Park and Ride 510 and 511 being severely disrupted.
More to come.
For up-to-date information about the county's roads, visit our LIVE Norfolk traffic map.
Join our Norfolk Travel Information group on Facebook for all the latest traffic news in Norfolk.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here