Authorities are not quite sure who has put up a set of temporary traffic lights which are causing traffic chaos.
Drivers are facing up to an hour of delays on the A47 Acle Straight due to a set of temporary signals which were put up on Friday morning.
Highways England, which operate the trunk route, said they had not planned roadworks or maintenance on the route, and they also had not been informed of any other agencies carrying out works.
A spokesman said they should be informed ahead of any works on a route like the Acle Straight, even if emergency work had to be carried out.
He added: 'Drivers are facing 45 minutes to an hour extra on their normal journey times.
'Traffic is moving but it is very slow, about 10mph heading in and out of Great Yarmouth.'
The planned roadworks at Fullers Hill are compounding the issue, as drivers are funnelled into one lane heading into town from the Vauxhall roundabout.
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