The busy A10 was closed for two hours this morning after a van collided with a lamp post and brought down power cables. Drivers will face delays throughout today, as engineers carry out repairs.
Traffic was diverted via the A134, A1122 and A47 - leaving some drivers facing a 20-mile detour.
Police said the accident happened at 6.20am, at the junction with Mill Lane, just south of the Hardwick Roundabout.
Long queues quickly formed, with thousands heading into Lynn for work.
Emergency services had to wait for engineers to arrive before the road could be cleared.
Police said the driver of the van suffered 'non life-threatening injuries' and was taken to the Queen Elizabeth Hospital.
UK Power Networks said: 'We received a request from the police at 6.49am today to attend the A10 after a vehicle damaged an electricity pole and cables. 'Engineers were on site by 7.16am and worked to make the damaged equipment safe, which involved isolating power to 30 customers from 7.25am to 8.20am.
'Now that all power supplies have been restored, we will return to complete repairs after peak traffic hours today, as the remaining work will require the use of temporary traffic lights for safety reasons and we want to minimise any inconvenience for motorists.'
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