Nearly half of drivers admit to flashing their lights to warn other drivers of a speed check, according to an IAM poll of over 4800 motorists. The main reason for doing this is to save another motorist from being caught or fined.

This poll followed the prosecution of a driver last month, who was fined £175 and ordered to pay £250 costs after warning several approaching cars of a speed check. Nearly 70 per cent of respondents to the poll said that a driver should not be prosecuted for warning others – only 21 per cent believe they should.

IAM chief examiner Peter Rodger said: “The biggest reason for not flashing to warn of a speed check is safety, with ‘drivers who speed deserve to be caught and fined’ and ‘the meaning of the flash could be misinterpreted’, each polling a third of the votes from those who don’t flash.
“However, safety was also used as a major justification for those who do flash to warn of speed checks, with nearly 20 per cent saying they ‘wanted to avoid a possible collision when drivers see the speed check late and brake harshly in response’. The driver who was prosecuted for using his lights justified his behaviour by stating he used his lights to warn of a hazard.”
Flashing appears to be an accepted form of communication between drivers. Nearly 35 per cent of respondents say they ‘use their lights to tell other drivers they are giving way to them’, and 30 per cent ‘use them to thank another driver for giving way to them’. Less than 10 per cent of drivers said that they don’t flash at all.

Nearly 45 per cent of drivers feel that the Highway Code should contain a standardised code of what flashes mean. The fact that nearly as many people use their lights to thank another driver, as those who use them to invite another driver to come through, suggests there could be confusion as to what message people are trying to get across.

Rodger said: “Reassuringly, fewer than 10 per cent of respondents admit to using their lights aggressively to signal annoyance at what they consider bad behaviour on the other drivers’ part. So while the meaning of flashes is fuzzy, at least people don’t seem to feel it is an acceptable way to take out anger on other road users.”