Work has started on a £1.8m scheme to reduce speed limits and install speed cameras along a 26-mile (42km) stretch of the A35 in west Dorset.
The section between Charmouth and Yellowham, east of Dorchester, which is mainly single carriageway, has suffered 199 collisions and three deaths over a five-year period, National Highways said.
Average speed cameras will be installed in the villages of Winterbourne Abbas, Morcombelake and Chideock.
Speed limits will be also reduced by at least 10mph (16km/h) in several sections including around Bridport and Dorchester.
The work should be completed by the end of March, the highways authority said.
The body said the changes were based on “collision data, risk assessments, and insights into driver behaviour”.
South West Road Safety Manager Jack Mason said: “The initiative follows a long-term safety review and is part of our ongoing commitment to reduce the number of people harmed on the region’s roads.
“The speed reductions and average speed cameras will reduce the number and severity of collisions between Charmouth and Yellowham, improving safety for motorists and local communities.”
Details of the scheme and the programme of road closures for the work are available on the National Highways website.
