In London alone, more than 50 different utility companies have the power to dig up the highway.
There are a lot of people who need to know exactly what lies beneath the ground, says Stephen Palmer, the chief executive of the Institute of Highways Engineers.
Mistakes are dangerous and costly. To offset such risks, a language has emerged that is spoken in spray paint. Its lexicon is numbers, lines and symbols. Its grammar is most definitely colour.
And once understood, this pavement patois – based entirely on convention rather than law – puts even a basic speaker in touch with a subterranean myriad of pipes and cables powering the ebbs and flows of modern existence.
Used in warning signs the world over, red pavement paint denotes electricity. Thus red lines show where electricity cables run, says Kate Parkin, at UK Power Networks.
The numbers next to these red lines spell out either the distance to the kerb or the depth below ground (usually followed by a “d”) while the letters L/V means “low voltage”, H/V “high voltage” and S/L “street light service”. All of the above are, needless to say, dangerous to anyone inadvertently interfering with them. If there are letters as well – such as UKPN in the image above – that will usually designate which power company the cables belong to (UK Power Network in this instance).
Eagle-eyed pavement watchers may sometimes see the letters SWA written on the road (as in red in the photograph at the top of the page). This shows the cable beneath the ground is steel-wire armoured (SWA). Companies need to “know where the cables or pipes are before they start digging”, says Parkin.