Delays are expected on a rural Somerset road as safety improvement work begins later in January.
Councillor Tony Shire said there had been 22 accidents over the past 33 months on the A361 between Shepton Mallet and Nunney Catch Roundabout.
One had proved fatal and four were serious, he said.
Mr Shire said: "This scheme will help to make the roads safer for all users, and will decrease accidents across the county."
He added: "Detailed analysis of the accidents has indicated that five, including two serious, have occurred due to overtaking manoeuvres."
Work will include the introduction of double white lines where forward visibility is limited, improved warning signs and road markings.