MOTORING

Gisborne Times, Volume LXXXIV, Issue 12905, 4 July 1936, Page 11

MOTORING

THINKING IN SECONDS SAFETY MARGIN IN MOTORING *' * i When motorists drive an the higli-[wny-s and byways', other and wider ’considerations than their own pleasure- or business enter, for they immediately become. responsible in a large measure for the safety and convenience of the i-oadfi and all who rise •them, in the first place- it should be: accepted that no reliance can ho placed' on what tlio other person, animal or fowl wil do, -although in these days the fowl lias acquired rat-bo:’ more road sense, <yr Common-Sense than appears to be pose-:scs by a- number of pedestrans- and others. In an a.ddix’iS wiich Mr. F. .T. Field, chief engineer-, Forod-o Lmited, gave iin London in June of th s year, ho said that there- could he no doubt that disregard of certain elementary precautions on the part of the nonmotoring public and even of many motorists who were temporarily afoot, was alone responsible for many casualties. On the other hand motorists could not always be relieved of the onus of • contributory negligence which., in general, might be attributed to carelessness, inexperience, dullness of perception and mental, inc-rt a, which indicated that they were not aware, did not realise, and wire incapable of reacting instantaneously to a stimulons such as the imminence of an accident. In other words, they failed to appreciate the s toat-ion and did-not apply the brakes in time.

FACTOR OF TIME

Now time, even a bare fraction of

a second, meant so- much in an emergency. Here the art and skill of the engineer wav of little avail. He may have provided the most admirable braking facilities, but nothing he could do could off at the effect of wear and neglect, or make a drive.' al-irt so that lie; would apply the brakes with the utmost promptitude when their use was unexpectedly, but mo«i urgently, required.

Tinfortunacly. Hie occurrence of -something cf an unexpected chnrac ter temporarily deprived many d ivers cf muscular activity—a lapse of perhaps not- more than two seconds. He then dealt with tho purely inherent personal factor, namely the lag, or lapse, that wad inevitable between observation and the action of .applying the brakes, but no attempt was made to describe the cause or suggest a remedy, as the phenomenon was outside the scope of the engineer, being in fact a retarded muscular function, a subject which the physician alone could deal. From nve.stigations made, it was found that the lag varied considerably between car drivers selected at random, from 3 oil’s of a second in the case of a number of taxi drivers up to seconds for another class; others failed to respond to the expected signal even after trials. The general outcome cf the tests fad I c-arr-d that a lag of 3-5 of a second was the minimum, and 1 1-5- -iconds a fair a vet age for a number of keen and experienced mc-n. What is the. significance of those short intervals of time? As an example, assume- that th dliver cf a car running at 111 milc-s per hour were required to apply the- brakes with the maximum force when a selected spot was ’.cached, and not before. Hl'.s lag. Is 3-sih second, braking efficiency 75 per cent. The ear would cover ISO feet from the selected spot before it stopp- d. Another diiver with 1 l-sth -second lag repeated the performance with the same car, hut this time itwould travel through 141 feet and would he travelling at 28 miks an hour when it passed the spot at which the first man stopped. If the car weighed one ton it would have astriking force of -about 29 tons at that point, that was if it collided with it very substantia] obstacle. REDUCED EFFICIENCY

Tn result, instead of an actual braking efficiency, of 76 per cent., the corresponding efficiencies would be reduced to 60 per cent, in tho firstease and. to :3? per cent, in the second. Speaking generally, a motor car can be stopped on a good dry road in 4071. from 30 m les an hour without any appreciable skidding, and that performance co: responds with 75 per cent, hrak'ng efficiency and a loss of speed of nearly 167 m.p.b. a second, the distance of -Oft. being covered in 1 1 —sth seconds, or in the time required to count, one—two—three. The simple facts given here .serve to show how many facets there arc to the problem of safety on the loads co New Zealand as of other lauds; how, in addition to the stupid introduction of discourtesy and Intolerance to motoring, .there is behind every driving wheel that, inherent, almost ineradicable time lag whW: stands between safety and something else for .someone with -so mo velrele in some place.