What is the mysterious blue line on motorway exit in south-east France?

Motorists in the south-east of France may have recently spotted a strange new feature running along the hard shoulder of the A57 motorway near Toulon (Var): a thin, bright blue line.

Though it may appear to be either decorative or like a new kind of road marking for drivers it is neither: The blue line simply marks the presence of fibre optic cables running beneath the tarmac.

It is there to prevent the cables being damaged accidentally in case of roadworks. It is not there to affect drivers’ behavior in any way.

No driving fines are associated with the blue line. It does not mark a restricted zone or suggest a rule to follow. Drivers are free to cross over or even drive on it, where appropriate.

Its purpose is purely functional, making life easier for those who need to know what lies beneath the road surface. That it catches the attention of drivers is just a side effect rather than its purpose.

This kind of colour coding is not unique to France - Spain also uses these blue lines, along with a wide range of different colours for road markings.