The Road Conference.
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Precis oi Proceedings.
The impression left upon one's mind, after attendance at the three days' conference for which the County Councils Association was responsible, is the reverse of satisfactory. The meetings were, professedly, representative of road-maker and road-user, but the tone and views of the makers predominated. The ideas of the organisers, in regard to motors and motoring institutions, appeared to be of the haziest description; for example, when, on Saturday last, Mr. Sturmey suggested that the Society of Motor Manufacturers and Traders should be represented at a further meeting for the purpose of drawing up a scheme of procedure, he was vouchsafed the illuminating reply that they were already represented— by the Motor Union. Our readers can form their own views of the promoters' ideas of fairness, when we add that, in spite of the devotion of much space in the papers to attacks upon heavy motors, the abovenamed delegation does not include the C.M.U.A.
It will be a sorry time for the road surveyor and engineer if he permits himself to be led along these lines by ill-advised officials. If motor interests are persuaded that fairplay is to be withheld, they can take measures of other than a conciliatory nature to forward the provishm of better roads, and the use of available money to the best advantage. Many owners of motor vehicles consider that they have endured bad and wasteful methods long enough, but they are still willing to co-operate with the road authorities to the common end of good roads, if they are met halfway. If, on the other hand, their faith in the intentions and purposes of those who convene so-called "Congresses " be shaken, progress will be set back five or more years. We decline to believe that any but a small minority of lazy and incompetent road surveyors desires to see this.
The Papers.
We gave a complete list of the papers, in our issue of last week, and it is out of the question that we should make any considerable extracts therefrom. We shall content ourselves, therefore, by making our own summary of those points which are likely to interest owners and users of commercial motors, but we shall be happy, on application, to lend to any reader of this journal any particular paper in the list.
All papers were taken as read, which course had the advantage of economising time, though it did not aid the progress of business in every case. A fair proportion of those who attended the meetings had evidently never studied the advance copies of the papers, and their remarks, consequently, and much too frequently, were inchoate and disjointed. Those authors who, in some of the sections, briefly explained the contents of their papers, by permission of the respective chairmen, did not suffer the annoyance indicated, and this coarse appears to us as one which might be generally adopted in parallel cases.
Construction and Maintenance of Roads.
We were delighted to observe the advice, in the paper (No. 0) by Mr. W. Nisbet Blair, borough engineer of St. Pancras, that the cross-fall on an asphalt-paved road should be much flatter than is now often found in the metropolis. Mr. Blair recommended 1 in 45, or 1 in 50, and we would urge this view upon the borough engineers and surveyors who have side-falls as steep as 1 in 25, or even 1 in 20, at numerous points where motorbuses have to run. As the writer has many times pointed out, and more particularly on the occasion of his paper before the Road Conference of 1908, at Olympia, the limit of adhesion for a robber-tired motorbus, under surface conditions which are often experienced, is reached on an incline of 1 in 30, and upon any steeper section of cross-fall a driver has to perform a series of balancing feats.
Mr. John A. Brodie, the city engineer of Liverpool, brought forward some valuable and informative suggestions (paper No. 10) in regard to the necessity for a standard of traffic and wear, and appealed for some uniformity of statement in this connection. He adduced convincing arguments to show that this might be expressed in terms of the tonnage-life per yard of width for a given thickness of coating. He had found. in Liverpool, that granite setts, accurately dressed and laid six inches deep by six inches to eight inches long, by four inches wide, on a sound concrete foundation of it least eight inches deep, with a small sand bed between the underside of the sett and the concrete, the joints being thoroughly racked with hard. shingle, and afterwards grouted with a permanent pitch mixture, gave a life equal to at least 7million tons per yard width. Ordinary macadam, water-bound, gave a life of about 100,000 tons only, or about 75 times less, but this was increased to at least 730,000 tons per yard width, or by 71 times, when laid as in the following manner :—A portion of a macadam road surface, to a depth of 41 inches, is removed and replaced by an equal depth of ordinary macadam stone, laid in two layers spread in the ordinary way, and, after dry rolling, the interstices are completely grouted or poured up with a permanent pitch and sand mixture, so that each stone is embedded in or surrounded by the mixture, the whole being again rolled while still hot, with a ten-ton roller, until consolidated and rendered thoroughly impervious.
Mr. Brodie also directed attention to the valuable results he had obtained with macadam concrete blocks, the wearing surface consisting of selected macadam, placed by hand on a true surface in a mould, the wearing surface downwards, and strong Portland concrete material being subsequently filled in to a uniform depth of about inches. These blocks, which are finally subjected to hydraulic pressure, gave excellent results, as regards wear and quietness, when properly matured.
Tarred Roads.
A variety of opinions on the matter of tar-spraying were expressed, but the surveyors who evidently possess some experience are agreed that it is important to undertake the tarring of any macadamised surface when the weather is dry. It amused us, even if the lines made one feel rather sad, to read in the paper (No. 11) by Mr. G. Carpenter, the West Riding Surveyor, that: " The outcry against the use of road scrapings as a binding wouh, without doubt, be reduced, if it were not that madmen had it easier to produce a. finished appearance with the aid of a liberal supply of scrapings than without." We can hardly follow why it should be hard, with proper supervision, to prevent this practice, which Mr. Carpenter proceeded to explain was quickly stopped—whenever detected. He is of opinion that the ultimate cost of a macadam roadway, made with a bituminous binder, will in all probability be found to he as cheap, if not cheaper, than the ordinary water bind.
liar ing regard to the satisfactory wear of a number of roads with tarred surfaces, where the action of heavy motor traffic is withstood, we have no hesitation in replying to a remark (paper No. 12) by Mr. A. I). Greatorex, the Borough Engineer and Surveyor of West Bromwich. He writes : " It is unwise to continue to make expensive roads by the same methods, when it is known that they will be torn up again almost immediately." Every ratepayer will agree.
Mr. Henry E. Stilgoe, the City Engineer and Surveyor of Birmingham, expressed the following opinion (paper No. 151: " Taking into consideration the items of utility and eost and the facilities for construction and repair, the author is of opinion that, of macadamised roads. one constructed with good stone (water-bound) on a proper foundation, and the surface properly coated with hot coal-gas tar, is the best. The system of tar-spraying roads by machinery has greatly facilitated and reduced in cost what the author considers one of the greatest boons conferred upon the users of macadamised roads. It lessens wear and tear, prevents damage by suction of pneumatic tires, reduces dust to a. minimum, reduces mud, and generally increases the life of the road."
Heavy Motor Traffic.
The most direct attack upon iron-tired motor wagons was made, in paper No. 12, by Mr. Greatorex. He stated, in more than one place, that our highways are being illegally used by these vehicles," and expressed the view that the damage was caused by the heavy weight carried per axle, and the speed at which the vehicles ran. He asserted that 75 per cent. of the " heavy motorcars or tractors " are run on steel tires, which is only approximately correct if his statement be confined to steam lorries and tractors, as any commercial motor is classed as a • ' heavy motorcar " if its unladen weight is in excess of two tons. He complained that, with a load of five tons, as ordinarily placed upon the platform, the hind axleweight fully loaded is above the legal limit of eight tons. He also stated, in support of his view that it is the practice of owners of heavy motors to break the law, that : • ' You will see advertisements in the technical papers of a motor tractor drawing a load weighing 13 tons, and these advertisements are constantly repeated as evidence of the capabilities of these neavy motorcars." Further, he proeeeded to argue that the speed limit is habitually overreached. One of the speakers corrected Mr. Greatorex, in regard to the matter of the advertisement with respect to a, tractor, and pointed out that not a few owners chose to haul two trailers, but that they registered the tractors. in such cases, under the provisions of both the Locomotive Act of 1898 and the Heavy Motor Car Order.
Mr. Creatorex urged that the provisions of Article XII and XIII of the Heavy Motor Car Order, in regard to illegal weights, should be enforced, but a brother engineer. in contributing to the discussion, remarked that this was of no avail, as no penalties were enacted. Another speaker, from the users' side, pointed out that any breach of the Heavy Motor Car Order, in regard to excessive speed, excessive axle-weight, or other matters therein prescribed, rendered the driver and/or owner liable to a fine of £10, which is the case. The same speaker protested against the suggestion that owners of commercial motors habitually broke the law, and added that those who used their machines properly and fairly would be most happy to see others who wrongfully used the highway fined. The unfair action of men who did overload rendered it very hard for the contractor who always endeavoured to comply with the requirements of the law.
Larger-diameter Wheels.
'We refrain from reproducing the numerous arguments and appeals for larger diameters of road wheels. Colonel Crompton led the way, as he has done on many occasions, and about ten others urged the same development in wheel construction. It is evident that manufacturers and users of steam lorries will have to take steps gradually to increase the bearing surface upon the driving wheels of their machines, and we are satisfied that the sooner this is done the better will it be for them in all respects. For example, the user of a highway who has wheels of such dimensions that the load per inch of tire width on any wheel does not exceed 600Ib., compared with another user who has as much as 800lb. per inch, will have a very much better answer to any claim for alleged extraordinary-traffic damage. The crux of the matter is this : evidence is now available that a large number of macadamised roads are damaged by the weights which are permitted under the Heavy Motor Car Order of 1904, and it behoves manufacturers to take steps in the direction we have indicated, at once, and not to wait until such increases are forced upon them by law.
"Patching" Macadamised Roads.
Mr. J. S. Pickering, Borough Engineer of Cheltenham, drew attention (paper No. 14) to the great economies he had been able to effect by a system of "patching." He condemned the practice, now prevailing in towns and in county districts, of allowing the roads to get into a general state of disrepair, and then to re-surface them. One alternative, he stated, was to fill in depressions with loose stones, which were ground to dust by heavy traffic, or scattered by fast-moving traffic. He proceeded: " If a newly-macadamised road is kept under observation during wet weather, it will be seen that inequalities of the surface, which at first appear to be small and unimportant, gradually develop with the action of the traffic and the rain water, until depressions occur which allow the water to be retained and the structure of the road to be weakened. Instead of allowing these depressions to remain, and to become worse year after year, they should be systematically repaired as they appear." A self-contained steam roller, constructed by Mann's Patent Steam Cart and Wagon Company, Limited, of Leeds, is used, the gross loaded weight being 9.1 tons. This machine, Mr. Pickering finds, " does its work quicker and better than an ordinary steam roller, and its cost has already been more than saved in economy over the old system of carrying out repairs." He finds that the roller can be made to pass over a patch 18 inches long no less than thirty times in a minute. Briefly, Mr. Pickering's belief is in the proverbial " Stitch in time," which materially reduces the cost of maintenance.
We have other evidence before us to show that such a system of patching is capable of saving many thousands of pounds a year for any authority which is responsible for the upkeep of macadamised roads. Such a machine, of course, can also be used for the cartage of materials, or as a tractor.
"Cubette" Paving.
There were a few references to this system of paving, interest and belief in which grows each year. The writer first examined roads so " armoured," in company with Mr. John A. Brodie, at the end of 1904, on the occasion of a visit to Cologne and other German cities. The cubes are now largely supplied from English quarries, where they are broken by a special machine, and they are, roughly, 21-in. along all faces. When laid on sand without any coherent grouting, they do not stand the dispersive action of heavy motors, but they form an admirable and cheap paving when laid in pitch mixture or other bituminous matrix. The same weight of stone, compared with ordinary granite setts, will cover twice the surface, and the cost per ton is about one-third that of the standard dressed setts.
Mr. Brodie, in his paper, estimated the life of this " cubette " paving, under country road traffic, at 30 years. Mr. Stilgoe calculates the cost, " on a bed of bituminous binder, with the cubes well rammed into it, and grouted up with a mixture of pitch and oil, at 7s. 9d. pee square yard.
The Cost of Main Roads.
There is a cry—almost a parrot cry—from road surveyors about the increase in the cost of maintenance of the main roads of this country. They appear to ignore the fact that so little was spent, upon many an old coaching road, between the inauguration of the railway era and the considerable advent of motor traffic some seven years ago. It is no astonishing thing to find some increase in cost, for a large number of so-called main roads were never called upon to bear much traffic until the motorcar drew attention to their neglected condition, but it has to be admitted that the popularity of cycling had, prior to the passing of the 1896 Motor Car Act, brought about a considerable improvement in road surfaces, and that all roads in the country were not devoid of good " crusts." The fact remains, none the less, that much of to-day's expenditure is clue to the absence of adequate outlay during several decades between the year 1831 and the year 1891. Mr. W. J. Taylor, the County Surveyor of Hampshire, gave the following comparative figures of the annual outlay on maintenance and repair of the main roads in England and Wales during the past nine years, for the 12 months ended each 31st March :— 1901—miles 26,598, cost £2,024,711, rate p. mile £76.1; 1901—miles 27,223, cost £2,366,163, rate p. mile £86.9; 1905-miles 27,367, cost £2,406,754, rate p. mile £87.9; 1996 • miles 27,380, cost £2,478,481, rate p. mile £90.7; 1907• • miles 27,556, cost £2,529,137, rate p. mile £91.8; 1908-miles 27,600, cost £2,644,718, rate p. mile, £95.4; 1909—miles 27,600, cost £2,766,003, rate p. mile £100.2.
He proceeded to point out that the heaviest burden has fallen on the south-eastern half of England, where motorcar traffic is more general, and he divided the blame between the studded tire, the leaping or galloping motion acquired by cars at high speeds, and the use of small-diameter wheels upon heavy vehicles. He proceeded : " Most of the road authorities have for many years set themselves the task of abolishing the use of soft road materials, such as limestone, flint, and gravel, and of using in their place hard stones, such as granite and basalt, and they have made and compared innumerable experiments to ascertain the stones most suitable to the varying local conditions of climate and subsoil. This work, which must be accelerated under new conditions, will, however, take a long time to accomplish, as the cost of laying down a 3M. consolidated coat of granite, on those 4,500 miles of main roads alone, in the south-eastern half of England, which are yet repaired with local stone, will be about £5,000,000. . . It is hopeless to think that substantial foundations can he built into our roads—except in special cases—as the initial outlay is so great and the improvement so local; the work will almost entirely be effected by dealing with the whole area of surface at once—that is, by gradually thickening the road crust, by laying down over the whole area of the roads a little more material each time they are repaired than has been worn out, and so accumulat ing a more substantial road crust. . If, in addition, we can use bituminous coats and matrix, we may hope to resist undue wear and satisfactorily provide for—as far as that is possible—the demands of all forms of traffic, but it is very difficult to see how the funds necessary to accomplish this work are to be raised."
The foregoing remarks are of much interest, and the present proposals of the Chancellor of the Excequer may tend to help Mr. Taylor and other surveyors in the directions of the more-rapid improvement and strengthening of roads, although it cannot be imagined that any money will be voted without supervision. It appears to us, so far as the cost and maintenance of highways go, that a great deal of present-day expenditure is wasteful and misapplied, but that the lack of information, of standards, and of any true bases of comparison, renders it difficult for those counties which are least ettivient in this department to be penalised as they deserve. Until such discrimination is possible, motorists will have to put up with the injustice of the accusation that they are wholly responsible for the increases noted.
Is there Suction?
Colonel Crompton (paper 18), after strongly advocating the use of bigger wheels, and pointing out that their weight increases only as the diameter, and not as the square of the diameter, made some passing references to " suction." We quote from his paper : " It is necessary here, therefore, to point out that what is called the • sucking action ' of pneumatic tires has never been proved to exist. The action which undoubtedly does remove the small particles of the road, leaving the large particles to be crushed into finer particles by the rigid wheels of other vehicles, and which crushed material is either blown away by the wind or raised as dust by succeeding pneumatic-tired vehicles, is due to an entirely different action, which is not suction. It is that which arises from the deformation of the tire as it approaches a road surface, which makes it scour or scrub that surface with a comparatively light force, equivalent to brushing it, and which has only effect on a water-bound road when the latter is either muddy or perfectly dry. The feeble binding power of the water as the road approaches dryness is insufficient to resist this brushing action of the pneumatic tire, but a very thin coating of bituminous or tar binding entirely prevents it."
Sir J. H. A. Macdonald, on the other band (paper 19), after dealing fully with the bad effects of horses' hoofs upon the roads, especially when drawing heavy loads, was responsible for the following paragraph: " Every horse in pulling a load uses his toe as a gripping power to prevent slipping when he sets his weight forward to move Lire load, and this is, of course, done with more force when ascending a gradient. Now, as the stones in a road bound with mud cannot be tightly held, the horse's toe slightly moves a stone in its seat, a wheel going over that stone moves it again, and the wearing of the sharp surfaces has begun. Whenever by repeated movements the stone has got slightly rounded, the next kicking action of the toe of the shoe tends to pull it out. Then comes the action of the wheel. The dimple left by the horse's toe is crushed down on both sides by the wheels, and, if the stone is loose in its hole and the edge of the wheel conies on the side of it, the wheel turns it over and prises it out, or, if the stone is out of the hole, the crushing down widens the space left empty. Then comes the rain, and small puddles form. Another toe deepens the hole, another wheel widens it, and so a large puddle is formed, from which water works its destructive way down to the bottoming, exposing the whole to the bursting effects of frost. While this process is going on the motorcar comes along. The pneumatic tire sinks into the hole, and with a sucking action pulls out the loose mud or loose detritus, and so adds very seriously to the damage." We would suggest that the proper word to be used for " suction " is " dispersion." There is no question that the rapid passage of a plain or studded pneumatic tire causes the water and loose particles to be dislodged from any depression in the road, which depressions have first of all to be started, as Sir John Macdonald points out, by the horse. The perfection of the surface of many tarred roads, over which such motor traffic freely passes without harm, proves the correctness of this contention. There is probably something to be gained by a correct apprehension of the action which takes place, and which we maintain to be merely a tangential thrust on the surface of the road. When one combines the motion of rotation and translation which simultaneously affect any point in a road-wheel tire, one realises that the change from compression to tension takes place upon the road at a point in a rigid tire, and during a very short period of contact in any resilient tire. We adhere to our view, often expressed, that there is no suction, as properly understood, and that the action is merely dispersive.