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WEAR AND TEAR ON ROADS.''

29th October 1908
Page 14
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Page 14, 29th October 1908 — WEAR AND TEAR ON ROADS.''
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Which of the following most accurately describes the problem?

With the passing oi the Motor Act of 1896, which legalised the used of the automobile, the roads in this country saw the beginning ot that, great and growing tide ot motor mum: which this Congress has set itself the task of studying and debating in all its phases. 'the following table shows the growth of motors—heavy and light--in the United Kingdom during recent years : And the following statement gives the rise in annual cost of the Main Roads in England and Wales during the past six years, and the estimated cost for the year 1909 :

1907 ••• ... 27,556 2,529,137 91.8

But the excessive wear and tear inflicted by the rapidly growing volume of motor traffic has in very many cases not yet been made good, and the rise in cost will doubtless be accelerated during the next few years, irrespective of any increase in the number of cars. The total number of cars registered in the United Kingdom, is, with the exception of those in the United States of America, greater than in any other country, as the following table (which I have borrowed from Lord Montagu) will show : The wear and tear bv motor traffic is, of course, greatest in those counties near and inimediately surrounding London, and it rapidly diminishes a.s the distance increases from that centre of movement. But English engineers who are responsible for the upkeep of roads in this portion of the country, of which the Metropolis is the centre, have a double burden to bear; not only is the circulation at its maximum here, but it lies in a portion of the country where there are no local supplies of good road material, and which therefore has to be imported and at great cost. If an imaginary line be drawn across England from Scarborough in Ihe northeast, to Weymouth on the south coast, we have to the southeast of that line the part of England to which I have just referred; this suffers more than any other part of the country from the wear and tear of automobilism. It contains no local supply of road metal other than flint, limestone, or gravel, none of which are capable of taking any but the lightest traffic, and that only ii ii h the extremes of mud and dust, and all are certainly inadequate to resist the wear and tear of modern automobilism.

Abandon Limestone.

It will thus be seen that the problem of dealing with the wear and tear of automobile and other traffic is very serious in this port of England, and the road authorities which are necessarily compelled to abandon limestone, gravel, and flint, and on all heavily-trafficked roads have to draw their supplies from the quarries in other parts of the United Kingdom, or from those of France, Germany, Nora% av, and Belgium. The writer is the responsible Engineer for 541 miles of purely rural main roads in the county of Hampshire, which lies in the portion of England now under consideration, and the preceding diagram will show the changes from the weaker to the stronger kinds of materials now taking place, and the increasing cost of this effort to compensate for surface wear and to accelerate a change which has been pressing Si the traction engine was first used. The cost of abandon the flint, gravel and limestone surfaces of the 4,5oo mile main roads now coated with these materials in England Wales, and of providing them with coats of basalt or grant would be about £3,000,00a, and can therefore only be um taken gradually.

One of the chief causes of this unusual damage is a. butable to the defective design of the wheel, the dam. being further increased where the wheel is the mediurr the motive power. The rolling effect of a wheel of la diameter in passing over unevenness in the surface is acci partied by less shock than in the case of a small wheel. %s consequent saving to the road. Roads under the writi control have suffered greatly from small-diameter whe particularly from those of the heavy commercial motor, wit sink into the weaker roads, and corrugate their surfaces pushing or forward effort ; the wave motion thus impartet the road crust badly crushes and reduces the stone un which are thus subjected to great improvement,

In regard to faster moving light cars, the unsatisfact rolling contact between metalled wheels and ordinary I-, surfaces, especially at high speeds, has necessitated the in rubber tire, and, whilst on well-made macadam roads, wh the pieces of granite or basalt are well interkeyed and (Id' into close compact with a minimum of liner particles in interstices, the suction action is not so greatly noticep if the traffic be well distributed, the reverse is the case our flint and gravel roads. Under the combined influen of excessive speed and weight, the finer particles of th latter roads are swept out, and the surface crust is loose] and disintegrated, whilst the unkeyed material is crust and the loss is great. The armoured or steel-studded • has, however, proved to be a potent instrument of x% destruction, and the wear and tear of roads due to this fo of wheel has been widespread. By reason of the leapi

ation acquired by motors running at high speed, the vehicle neceds by a series of impacts, and not only are the heads the steel studs destructive by reason of the shocks or )ws by which their heads are continually brought down on the road surface, but cutting or grooving of the road rfaoe ensue from " slip." When the driving wheels leave ?„ ground, they " race " or revolve at a greatly-accelerated locity, and, when they again come down on the road, at excessive velocity has to be arrested and reduced to the eed of the car by the road surface, portions of which are zked out in its resistance to this tangential effort of a id of circular file.

Keep Off the Crown.

flu financial problem of meeting this wear and tear is

c that is occupying the very anxious attention of all road thorities, and their engineers in this country. So far, n'e is a general consensus of opinion that as rapidly as ads can be obtained we must abolish from all our 11101.1; aviIv-trafficked roads such material as flint, limestone, and avid, ond use in their place the toughest and hardest tterinfs that can be procured, and that they must be sliprted on unyielding foundations: by treating their better rfaees with tar, and by flattening the camber where it is cessive we find that many of the effects of motor traffic very largely met.

In this question of wear and tear, I have more especially all: with the long mileage of trunk road between our cities d towns, as the problem is not so difficult in the latter, tere there are substantial pavements, where the traffic is eat and consequently the wear distributed, and in addin the speed is much reduced. To obtain the roost ceono mical rolling contact between the wheel and the road, the skill of two different people is required, that of the road engineer and that of the designer of the motor, and if, as undoubtedly is the case, the road engineer has many and great improvements to make in the construction of roads, his efforts to obtain success have not perhaps been fully met by the other party, whose active co-operation is so essential to a more perfect state of things. To secure this most economical rolling contact, many millions sterling will have to be spent in this country, and it is idle and illogical to suppose or to expect that the road authorities can bear the whole burden of it, or even that it is desirablethat it should do so; self-propelled traffic must take upon its shoulders some portion of the task.

Some makers appear to believe that by broadening the wheel they compensate for the small diameter, but this is not so : the limit of usefulness in broad cylindrical tires is quickly reached, when it is borne in mind that they roll on cambered roads, where the inner edges only of the tire beat upon the surface, and that only on the unscientific condition that the road surface must be made to yield for it; it is of little use to after the method of cross fail, as the traffic adheres to the centre only.

Is it impossible for motor engineers to go even further than increasing the diameter of wheels, and to save a vast outlay on the wear and tear of roads, as well as on the vehicles itself, by giving us some better method of road contact than that supplied by the unyielding cylindrical wheel of the motor or traction engine? A wheel of this kind is only a satisfactory element when rolling on a true plane and in a straight line, conditions which are unattainable on ordinary roads.

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Organisations: Congress
Locations: London

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