The importance of proper lighting
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Tim Blakemore assesses the dangers of faulty vehicle lights and looks at a number of ways that better use of lights could improve road safety
AB SVENSK Bilprovning, the Swedish Motor Vehicle Inspection Company, includes all of a vehicle's lighting system in the category of its "communication system". That is an apt way of describing the function of vehicle lights for they do indeed either communicate a driver's intentions to other road users, enable him to receive information better, or simply warn of a vehicle's presence.
If, before they passed their driving tests, more drivers were taught to think of lights in this way and reminded of it periodically after the test, perhaps there would be less of the dangerous, arbitrary use of lights which occurs so often on our roads.
I'm sure you know the kind of thing I mean. There are the "historical signal givers" (i.e. the ones who pull out to overtake parked vehicles, then signal, then look in the mirror) or the drivers who refuse to use — or perhaps are genuinely unaware of — the correct signalling procedure at roundabouts.
Then there are the two notorious related species of driver who give misleading signals — the drivers who remain blissfully unaware that they have been signalling right or left for the past five miles, and the ones who like to flash their headlamps as often as possible.
But you can never be sure if they mean "I'm coming through" or "I'm not coming through" or maybe just "I'm flashing my headlamps".
Of course we mustn't forget "the dazzlers" who seem to delight in aiming to blind every other driver on the road by leaving their headlamps on main beam regardless of oncoming traffic and leaving their high intensity rear lamps on regardless of the weather conditions. This latter practice, particularly prevalent at this time of year, must surely now be the most common abuse of lights in Britain today.
Last, but by no means least dangerous, there are the "one eyed monsters" — the vehicles with only one headlight or one tail light which can convince you up until the last breathtaking moment that you are approaching or following a motorcycle.
Hgv drivers are far from being blameless of all these dangerous practices but in general they are much better disciplined in the use of lights than car drivers. Indeed it is quite remarkable to what extent experienced lorry drivers can communicate simply by using various lights. The messages can vary from "Thank you" to 'you've passed me now" to "Watch out there is a ministry check (or radar speed trap or accident) ahead" — each message with its own particular sig nal, to "That was a silly thing to do".
CB radio hardly seems necessary when such non-verbal conversation is possible.
However, as far as the development of the hardware of vehi;le lighting is concerned (especially headlights) commercial vehicles have tended to be the poor relations of the industry.
The reason is based on simple economics. Tooling up for a new design of headlamp can cost a manufacturer hundreds of thousands of pounds. If that headlamp is going to befitted to a top selling car like the Cortina, for example, then the headlamp manufacturer can be fairly confident of sufficient turnover to justify his capital investment.
On the other hand if the lamp is only going to be fitted to a heavyweight commercial vehicle then the number sold is bound to be drastically smaller.
Over the past two years though, cv lighting has improved dramatically. Scania, for example, has responded positively to criticism of poor headlights on its earlier models by fitting much improved lamps to the new GPR range. Rectang ular in shape to give better light distribution, the lamps are claimed to be 30 per cent more effective than their predecessors. !n anticipation of forthcoming EEC international type approval regulations, Scania, like IVECO with its latest tractive units, has fitted a manually controlled levelling system to the lamps to allow beam height to be set according to the loading condition.
Volvo has always considered it to be important that its commercial vehicles should have efficient lighting.
The Swedish manufacturer argues that it is no use fitting powerful lamps if dirty, wet or snow covered lenses partially block the beams, so headlamp washers/wipers are fitted as standard. Also the headlamps are mounted as high as possible to give the best possible forward throw of dipped beam.
Weight reduction and the improvement of vehicles' drag coefficients are two problems currently exercising the minds of many lighting engineers at the leading lighting equipment manufacturers. Once again this is in response to demand from car makers.
For commercial vehicles these considerations for lights are relatively unimportant, but there could be spin-off benefits for cv operators. Lucas, for example, has introduced its Homofocal system which involves the use of a patented DMC (dough moulding compound) plastic to mould a complex reflector cap able of "squeezing" maximum light from a compact and shallow unit.
Lucas says that the intricate, precise reflector shapes made from the non-shrink, corrosion resistant DMC would have been impossible to achieve using traditional metal pressing techniques.
The weight of a headlight's diffusing lens could be reduced by about two thirds if the lei were made of plastic instead glass. But Gerhard Lindae, chi development engineer,Autom tive Equipment 2(Headlights ar Lamps) Robert Bosch GmbH, b lieves that "the introduction plastic lenses can only take pla when it has been proven that ti lighting effect of the headlarni can be maintained over a lor period".
The problem is that plastic ju cannot match glass as a lei material in the areas ( weathering resistance, chemic resistance and resistance abrasion.
Many tests have been card( out including coating the out surface of plastic lenses with hard laquer to resist th weathering and abrasive we According to Gerhard Linde "These influences are so great practice that existing technoloc is not sufficiently advanced • satisfactorily solve the pro lem."
It is reassuring to know th lamp manufacturers are at lea aware of practical operation difficulties. While the unit cost replacing a single bulb, or even headlamp may be relatively Ia.% when the number of vehicles a fleet and/or the fiequency repair increases, the total cost lighting maintenance can b come very significant. In the ii terest of road safety it is impo tant that these means communication are maintainE and used properly.