Works is expected to start on Monday to install average speed cameras on the A149 in West Norfolk.
Cameras will be installed between the Knights Hill and Snettisham roundabouts as part of the Norfolk Safety Camera Partnership scheme, being implemented with Norfolk County Council.
The work is expected to take around three weeks to complete and will take place between 8pm and 6am.
The road will remain open at all times with traffic lights directing people through overnight lane closures, a county council spokesman said.
Chairman of the safety camera partnership, assistant chief constable Simon Megicks, said: “We have continuously been in support of road safety improvements on the A149 between Castle Rising and Snettisham.
“Speeding is one of the fatal four offences which makes you more likely to be killed or seriously injured in a collision alongside drink/drug driving, driving while using a mobile phone and not wearing a seatbelt.
“Average speed cameras have been proven to reduce speeding and help to reinforce understanding around speed limits, set at the maximum safe speed to travel on a particular stretch of road.
“In 2016, the decision to fund and proceed with this scheme was agreed by the Safety Camera Partnership Board and it is pleasing to see this finally coming to fruition.”
Martin Wilby, county council cabinet member for highways, infrastructure and transport, said: “This scheme is expected to improve safety on the stretch of the A149 where there have been 50 personal injury accidents over the past six years, of which three were fatalities and 13 involved serious injuries.”
Police and Crime Commissioner Lorne Green said he had “long held the view” that action was needed on the road.
County councillor Andrew Jamieson, member for the North Coast division, said: “Local residents are clear that a range of safety improvements are needed so we have been looking closely at a number of schemes in addition to the safety cameras.
“This work will soon see improvements to signs and road markings at the Lamsey Lane junction, and we would like to see a lower speed limit which is why we’re currently consulting on a reduction from 60 to 50mph on two stretches of the road.
“Through this consultation we have also heard loud and clear that some proposed junction closures aren’t the right thing to do, so we won’t be going forward with those measures, but we will continue to look for future improvements on this vital route.”