It is using 140 litres of SmartWater solution on cables being laid along a 17-mile stretch of motorway between junction 8 of the M60 near Sale and junction 20 of the M62 near Rochdale as part of the smart motorway scheme.
Nearly 50 miles of cables will run through underground pipes along the route, which will be used to power electronic message boards and signs that display the variable speed limits.
The new equipment, which also includes around 1,000 lighting columns and full CCTV coverage, will be mainly powered using fibre-optic cables, which have no scrap value, but some metal cables are also being used.
SmartWater was created in 1993 by a former police officer and his brother, a chemist, and is now widely used as a theft deterrent. The invisible liquid can only be seen under ultra-violet light and contains a unique, indelible forensic code which can be used to irrefutably prove ownership and link criminals to a crime scene. It is being painted on cables, equipment and machinery being used for the smart motorway project.
Highways England project manager Paul Hampson said: “We’re investing millions of pounds of taxpayers’ money on the smart motorway scheme in Greater Manchester so it makes sense for us to do all we can to protect that investment.
“We’re covering the cables and equipment being installed as part of the project with SmartWater and warning thieves to stay away from the motorway as the police will be able to prove exactly where the metal came from if anyone’s caught trying to sell it on.”