A little understanding...
I'm unsure about the origins of flashing headlights but they have been widely used a courtesy signal amongst lorry drivers for many many years.
It might be argued that this is legitimate use because it forms part of the truck drivers common shared communication language and as such, all truckers have a full understanding of the meaning of each other's signals.
Understanding, however, is a strange thing - can you remember a time when you thought you fully understood something but then later realised that you'd got it totally wrong?
The ultimate meaning of any communication lies in the message that is received - this is not always the same as the message that was meant by the sender - in the case of flashing headlights this can cause confusion.
For example, some continental drivers use headlights to mean "I'm coming through" - imagine the chaos if this was interpreted as "I'm giving way". It doesn't matter what you are trying to convey with your message, the outcome of your communication will be based upon the way it is interpreted.
The starting point?
The 1969 copy of 'Advanced Motoring' neatly summed up the question of understanding as follows:
'The fact that a driver considers his own particular version of a signal superior to those which are authorised would not absolve him from blame, if his version were misunderstood and resulted in an accident'.
Similar information can be tracked back further - much further.
When discussing arm-signals the cigarette card series 'Safety-First' (dated around the mid 1930's) advised drivers that '...an incorrect or delayed signal is as dangerous as none at all'
This message is a maxim that could equally be applied to flashing headlights today.
Know the code?
The current Highway Code is clear and unambiguous about the use of flashing headlights; Rule 110 states:
'Flashing headlights. Only flash your headlights to let other road users know that you are there. Do not flash your headlights to convey any other message or intimidate other road users.'
Rule 111 adds:
'Never assume that flashing headlights is a signal inviting you to proceed. Use your own judgement and proceed carefully.'
The rules quoted above are a development of a basic principle which has been in the Highway Code from the early days. The 1946 Highway Code (rule 36) stated:
'Do not rely on signals to proceed given by unauthorised persons' (although, ironically, it also contained the 'I am ready to be overtaken' arm signal!).
Too easy to flash?
Flashing headlights seem to have been common practice amongst drivers from around the mid sixties/early seventies. The design of cars changed during that period providing a 'flasher switch' on the steering column. The column mounted switch made it easy to give a quick flash; before that light switches were generally on the dashboard with a foot operated dip switch. With flashing headlights just a fingertip away, the 'rules' started to take a back seat.
Doing as you're told?
Perhaps the most obvious problem is that many drivers interpret flashing headlights as an instruction.
'The emerging driver simply drove out of the side turning when instructed without fully considering the potential danger - if I'd been on a motorcycle I would probably have been killed.
Had the 'flashing' driver given way without a flash, my guess is that the emerging driver would have exercised more caution.'
Test it ...
If you are a flasher, you can test my 'more caution' theory for yourself.
When giving way, simply slow down or stop without flashing.
You will probably notice that the other driver takes a bit longer to make his decision and has a good look around before committing him/herself. You might also find that some drivers just sit there and are reluctant to move without your 'permission' (or instruction!).
I recall a situation when I was assessing a driver who flashed to give way to a van emerging from the right. And then nearly put me through the windscreen as he braked hard to avoid the 'idiot' who emerged from the left slightly further ahead. The 'idiot' had thought (quite reasonably) that the flash was for her!
Another situation I witnessed involved a lucky escape for a pedestrian.
A driver who was obeying the 'Give way to busses' rule flashed his lights to a bus driver - at that point a pedestrian who was standing behind the bus ran across the road and into the path of an approaching truck.
The pedestrian didn't see the truck because she was busy waving to say thank you to driver who flashed his lights to let her cross! The driver thought he was flashing for the truck. The pedestrian thought he was flashing for her.
While on the 'thank you' theme, don't be surprised if, when flashing someone to say thank you to someone, another driver suddenly pulls in front of you or a pedestrian dashes out - the signal could easily be misinterpreted by someone for whom it was not intended.
Don't be so aggressive!
Then there are the 'aggressive flashers' - these guys come up behind you on fast moving motorways and dual-carriageways 'telling' you to get out of the way.
I have even heard advanced driving instructors explaining how this can be done safely to get a slow moving driver to move over. My thoughts on this are that there is nothing 'advanced' about aggressive driving.
Sometimes drivers need a reminder that you are there. For example, big trucks can take ages to build up momentum on even a slight hill - if they are held up behind a slow car in lane two when lane-one is empty a quick flash might be legitimate as a 'Look, I'm here' signal... But not aggressive flashing - this can intimidate drivers to the point of risking an accident; or alternatively, provoke road rage.
But flashing headlights won't always be seen...
'Aggressive flashing' can perhaps be justified when used by emergency vehicles and executed as advised in Roadcraft (The police Drivers Manual); although it doesn't always work. I remember dark evening on the M62 when I was travelling as a passenger in a police car - hurtling along lane-three at about 120 mph we had more flashing lights than Blackpool Illuminations, but there were still drivers ahead who were totally oblivious to our presence! I'm sure this is a common experience for police drivers.
What if someone flashes me?
Perhaps having read the information above, you might be coming to the conclusion that flashing of headlights can cause as many problems as they solve, with potentially lethal consequences. So how should you respond to those who flash you?
The DSA manual 'Driving, the essential skills' offers sound advice. It states that before you act you should make sure that the signal is for you and that you understand its meaning.
It also suggests that you should ask yourself the following questions:
• What's the other driver trying to tell me?
• If I move, will it be safe?
• Is the signal for me or another road user?
• Am I causing a hold-up by staying where I am?
• Is the other driver really signalling or were those headlights flashed accidentally?
I'd also like to suggest some questions of my own, namely.
• Have I forgotten to turn my lights on?
• Have I forgotten to turn my lights off?
• Am I speeding?
With regard to the last one 'Am I speeding? ' Beware. if you warn others of a speed trap you could be prosecuted for obstructing the police in their duties (and of course, you shouldn't be speeding!).
There are legitimate uses for flashing headlights.
For example flashing from dipped to full beam can warn of your presence on bends and at junctions after dark or to warn of hidden danger during daylight hours.
A quick flash before overtaking might attract a two-fingered gesture from the driver ahead, but at least you will know he's seen you. In fact, his attitude might deter you from an otherwise safe overtaking manoeuvre that could be made dangerous by the other driver's actions.
You might not get home quick as a flash. But you'll arrive alive.