Megatons on the Motorway
By OLIVER STEWART
OVERWEIGHT vehicles are the trouble. Ever since motoring began certain groups of vehicles have been getting bulkier and heavier. But, unlike overweight men and Women, they have not been getting slower. On the contrary, technical progress has made them faster, so that they now assemble in themselves extremes of bulk, heaviness and speed. Just as overweight people are said to be a poor surgical risk, so these overweight road transporters are a poor traffic risk. It is upon them that attention should turn if road safety is the objective. Look at the differentials.
The pedestrian is at once the lightest, the slowest, the smallest and the softest road user. Everything else on the road is harder than he, bigger than he and weighs far more and goes faster. A small blow from a vehicle will suffice to 'break within the bloody house of life.' If he runs at full tilt into the back of a bus, he, and not the occupants of the bus, will get hurt. He is, in short, the most vulnerable and the least destructive. At the other extreme is the driver of the fast, heavy vehicle. He is the least vul- nerable and the most destructive.
The pedal-cyclist, straddling his frangible frame of wires and slender tubes, is but one stage less. vulnerable than the pedestrian and his destructive potential is but one stage greater. Next comes the motor-scooter. If a motor-scooter and a motor-bus, each doing 4Q m.p.h., meet in a head-on collision, the closing speed will be, 80 m.p.h. and the consequences predictable. The scooter rider will be killed and his machine written off; the bus driver will be uninjured and his vehicle slightly damaged.
So there are the different fates of the soft and the hard, the big and the small, the active and the passive. Our existing control systems almost ignore them. On our roads today he who cannot hurt, gets hurt; he who hurts, does not get hurt. And this arises not from vehicle speed or from vehicle weight, but from their product, Mom the 'ponderomotive' force, if I may borrow this Wonderful word from a scientific paper. Or, if we are not fussy about the definition of mass by velocity, we may, for our present purpose, loosely call it momentum. Momentum is the key to rational safety measures.
Destructive potential is at its peak in the vehicles which are both fast and heavy; the large, high-performance coaches, lorries, tankers and buses. Technically they are very beautiful, but, so far as I know, they are no better or worse maintained than other vehicles and' their drivers are no more or less likely to make mistakes. When a mistake is made the consequences are apt to be frightful.
It is strange that our legislators and regulation- makers should have been so forbearing, indeed tender, with these giants. Instead of holding them down to ever lower speeds as the products of their Weights and speeds have increased, authority— en the recommendation, ironically enough, of the Departmental Committee on Road Safety— has actually liberated them for higher speeds,-en- couraging them to charge along the lanes and Motorways like demented tanks, pounding the road surfaces to pieces and frightening the lives Out of other road-users. If the power to do damage were the criterion, these big vehicles, in order to be classed with ordinary cars, would have to be subjected to a speed limit of three or four miles an hour.
That may be unpractical; but it is my view that vehicular speed limits below any now applying are practical and desirable. The bad mistake of allowing vehicle weights and dimensions to rise too much for our roads has been made and, although there ought to be attempts to correct that mistake in the future, the only immediate way of mitigating destructiveness is to limit speed in relation to weight.
The order of permissible speeds is automati- cally given by a list of ascending all-up weights and speeds. No speed limit is required for the vehicle types at the bottom of the list: the cyclists, scooterists, mopedalists and motor- cyclists. Nor is there a case for a limit for small or medium cars. Sports cars may do over 130 m.p.h., but their weight is low, the weight-speed product is modest and there is still no case for a limit. But at about two tons and 100 m.p.h. limits might begin to apply and the maximum speed allowed would go down with the big vans, which are slower but much heavier, and attain its most restrictive with the massive and fast commercial and public service vehicles.
For these machines I do not think that speed limits of 20 to 25 m.p.h. would be unrealistic if we are genuinely concerned with reducing death and destruction, though commercially and perhaps politically they might be inexpedient.
Vehicular speed limits have long been common, but they have usually been mingled inextricably with carriageway speed limits or generalised seasonal limits. Moreover, no effort has been made properly to enforce them. The legend '30 M.P.H.' carried on the sides of London Transport buses showed that, in someone's mind, there was once a realisation that a vehicle so big, clumsy, heavy and fast should carry a re- minder of its destructive potential. But the re-
minder was lost upon the drivers and those who used to make out their schedules. To the weight- conscious passenger the speeds to which London buses are sometimes wound up by enterprising drivers on stretches in built-up areas (Whitehall, for instance) are positively hair-raising.
My proposals are for the abolition of all existing speed limits and the substitution of graded, 'ponderomotive,' vehicular speed limits based upon measurements. By curbing the big, high-performance coaches and buses and the fast, heavy goods vehicles, they would take the thunder, the crunch and the seismic shudder out of our motorways as well as some of the danger. These proposals, however, go against much of the exhortation in Parliament and the press.
For example, the drivers chiefly affected are the very ones praised for their skill and courtesy. The drivers unaffected are the very ones fiercely criticised : young riders of high-speed motor- cycles and drivers of sports cars. But whipping up detestation of these people is as purposeless as goading the courts to impose heavier sentences for motoring offences. Road safety measures really must be lifted out of the nauseating at- mosphere of moral posturing now prevalent there and placed on physical foundations.
Speed controls have always been unpopular. The 20 m.p,h. limit imposed in 1903 was re- moved in 1930 because it was ignored. The 1934 Act imposing a 30 m.p.h. limit in built-up areas was no better respected. Most road-users would gain if, in place of unenforced carriageway and seasonal limits, graded vehicular speed limits were imposed, based upon the dual concept of the' destructive potential of the vehicle and the vulnerability of its occupants. If properly en- forced, such limits might contribute to road safety as they would certainly contribute to road life without appreciably slowing the traffic that does not need to be slowed.
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