The Highways Agency have been testing new infra-red cameras on a stretch of the M25 in Kent and Surrey where the motorway is being widened.
The “smart motorway” widening scheme, from junctions 5 to 7 between Sevenoaks and Redhill, means the hard shoulder will now be used as a permanent traffic lane.
Regularly spaced emergency refuge areas have been provided and CCTV cameras installed so the Highways Agency can spot incidents.
Emergency services were called to Lyon Close in Crawley on Tuesday after a suspected acid attack.
The incident happened at around 7pm when a 22-year-old man was attacked by two men just and had the chemical poured over his face and hands.
The victim was taken to the Royal Sussex County Hospital in Brighton but was discharged early this morning.
The suspects drove off in a white Vauxhall Astra van along Harper Drive.