M25 barrier work begins between Godstone and Sevenoaks
Work to replace barriers on the central reservation of part of the M25 is expected to last several months.
The Highways Agency said new concrete barriers, which are intended to be safer, will replace the current metal ones between Godstone and Sevenoaks.
Work has started between junctions five and six and is scheduled to continue until spring 2013.
When completed construction will begin on a scheme to open up the hard shoulder as a fourth lane.