Highways England has said it will install a sensor on the M40’s “fog alley” in reaction to a fatal crash involving 30 cars two years ago.
The accident happened between junctions 9 and 10 in Oxfordshire on Valentine’s day 2015.
Highways England says the move would improve driver safety in the area, though the sensor is not expected to be installed until after April 2017.
Edmund King from the AA told the BBC he was “disappointed” it was taking “so long” and that the stretch of the M40 was described by many as “Fog Alley”, and was an area “prone to pretty heavy fog”.
Robert Pilott, 65, of Woking, Surrey, died in the accident in which six other people were seriously injured and 55 had minor injuries.