The carriageway will be reduced to a single lane at times
Ecologists have begun moving rare reptiles away from a major road which is due to be dug up and re-laid.
Dorset County Council is planning six months of repair works on the A338 dual carriageway, which runs from Bournemouth to the A31 near Ringwood.
Protected snakes and lizards are being relocated from verges between Ashley Heath and Cooper Dean junctions.
The reconstruction of the carriageway and drainage systems is due to begin in autumn 2010.
Work began on Monday to survey the area. Vegetation will be cleared to discourage birds from nesting there and a barrier will be erected during the winter to stop the reptiles returning.
The protected species include sand lizards and smooth snakes.
The reptile rescue operation will continue in the spring. While the rescue is going on, parts of the carriageway will be reduced to single lane traffic.
About 6.5 miles (10.5 km) of road will be completely replaced in the works at a cost of £26m.