The Modern Highway

Hawke's Bay Tribune, Volume XI, Issue 243, 18 October 1921, Page 1 (Supplement)

The Modern Highway

[We are indebted to the propriotoSTftteNew Zealand and Station Journal for the illustrations accompanying this article.] TTPON no one factor in the economics of a country does its social life and business prosperity depend than upon its U system of rdads, whereby intercourse is maintained between its various parts From the social standpoint, the importance of a good road system is very great, permitting the conduct of those functions such as mail con munication, interchange of ideas, educational intercourse, etc., which have become more than a luxury, and, indeed, an essential to the conduct of human affairs- On the other hand, looked at from the commercial standpoint, roads are an absolute necessity, whereby business traffic may be carried on, and without them the commercial life of a con inumtv would come to a standstill. To permit the fullest enjoyment of this intercourse, good roads are indispensable, and to anyone it is obvious that, where these are in existence, such intercourse may be conducted with the maximum of comfort and convenience, and at the minimum of expense, and business and commercial traffic carried on cheaply and easily. On the contrary, where communications are impeded by bad roads, heavy expense is incurred in conducting transport, with unnecessarily severe and expensive waste in draught. These conditions, as regards the roads in new countries are exemplified generally m the state of the roads m the cities and towns, as contrasted with those which may be termed country roads- In the former case the roads are usually in very good order, whilst in the latter, although numerous country roads are also in a fair state of repair, many more are not so, and especially is this the case where the traffic is heavy—W. M. Stevens, Government Engineer of Roads and Bridges, South Australia.

The question of good roads is ono which concerns tho town dwel’er equally with tho man on tho land. To the former thay mean added business; to the latter, comfort and life made bearable for man, woman and child. Nothing speaks better for a community than well-kept roads, and tho reasons why they are of such paramount importance are concisely stated by Mr. Stevens in the quotation heading this article. The modern highway is a live question in New Zealand to-day. Tt was one of the principle subjects discussed at the recent counties and municipal conferences he’d in Wellington. At the counties conference the Hon. J. G. Coates’ Main Highways Bill, which is

to be dealt with by Parliament this session, did not meet with general approval, while the Municipal Conference, though generally approving the measure, was at variance with the Minister in regard to the exclusion from its operations in respect of those portion of main roads traversing cities and boroughs. These differences of opinion it is not our intention to discuss now*. Our purpose is to endeavour to associate, in a good roads movement, all classes of road users to make a united demand for the permanent improvement of pub’ic roads and streets, and to secure better results for the money now exoended on public roads. The cry to-day is for efficiency and the reduction of waste and the first step to both is the provision of better roads; The economic loss to the country of operating motor traffic on roads unsuited to it is far greater than the average man has any conception of. We do not say that it is financially possible to lay down concrete roads even on all the main arterial highways, much less so on the country roads which serve as feeders, but we do assert that a different surface to loose gravel should be provided. A prominent road engineer was recently heard to state that the abundance of gravel available was the greatest drawback to the provision of good roads in Hawke’s Bay. If metal was less plentiful the local bodies would have to conserve their smaller supplies by using bitumen or tar for binding purposes and the users of the roads would be given a good smooth surface to travel over.

ASTOUNDING FACTS FOR MOTORISTS. It is a well known fact that it costs a great deal less to operate an automobile over a smooth concrete road than over a rough road. The difference in power required to move a ton load over a smooth concrete road and over a rough road is enormous. As an illustration, comparatively few’ realise that it takes ten times as much horse-power to move a motor-car over a road covet ed with loose gravel not packed down than it does to move the same load over a level, unsurfaced concrete paved road. A study of road conditions shows that unsurfaced concrete requires 2/.6 pounds pull per ton of weight. Covering that concrete with asphaltic oil and screening it then requires 49.2 pounds pull per ton. On water-bound macadam, level road and good condition, the pounds pull per ton increases to 64.3. That again increases to 68.9 w here the concrete is covered with Topeka top. Another increase is noted when the road is a good gravel road, where the pull is up to 70.2 pounds. An ordinary country dirt road requires 92 pounds and the same road in stormj weather, when there is a stiff mud on top, but firm underneath, this immediately jumps to 218 pounds. The maximum test was conducted on loose gravel, not packed down, and on a new road. That required 263 pounds, or nearly ten times as much power as was exerted on the level, unsurfaced concrete road. We leave it to motor car owners to work out what their saving in fuel, repairs, and tyres would amount to annually if hard surface roads were suddenly substituted for those they have to use at present. I ndoubtedly the aggregate saving in the running and upkeep of cars locally registered, together with the money’

wasted by local bodies on road maintenance would provide interest and sinking fund on loans sufficient to provide suitable roads for motor traffic. In Ontario, where the roads were particularly bad, the owners of motor vehicles met and decided to Tate themselves an amount equal to about two thirds of the money they would save by having good roads, interviewed tho local bodies and persuaded them to add to the self-imposed rate the amount annually' spent in road maintenance, approached the Government and secured a liberal subsidy, capitalised the total and provided the country with good roads which by means of th? sinking fund will bd free of debt in a

very short time. Is there anything to prevent the progressive and practical people of Hawke’s Bay following in the footsteps of their equally practical and progressive cousins in Canada ? CONCRETE ROADS IN AMERICA. A writer in “The New Zealand Farmer Stock and Station Journal, to the proprietors of which paper we are also deeply indebted to for the illustrations accompanying this article, says that tho next naif century has every indication of being the age of the highway. In this there is the example of the people of the United States 'of America. There are many limitations in these people no doubt? but absence of enterprise is very certainly not to be attributed to them. Wo find in that country that the mileage of the railways is immense, that there is almost a cessation of railway' building, and that what may he described as a feverish energy to construct hard surfaced roads, that is the concrete modern highway, is occupying the minds of the men who were foremost in the building of the railways. It is claimed that for the first time in tho history of that country, roads are being constructed up to the limit of the economic capacity of the nation. Tho programme of road construction is so large that it is doubtful if more than fifty per cent, of tho approved work can be completed, although the actual contracts are underway. Some idea, of the extent of these appropriations will be realised when it is known that in June, 1919. road projects had

been approved of which tho estimated cost was nearly eighty million pounds. Tlie mileage is described as a distance that would reach between New York and San Francisco, across tho continent nine times, or something over twentyfive thousand miles. Not all of this mileage is under construction, but it is definitely provided for by contract and agreement, and the actual construction is being undertaken as fast as economic limitations can be overcome. At tho end of that year, 1919, there were actually under construction, approximately, nearly sixteen thousand miles and over live thousand five hundred miles have been completed. "'lt is true that the whole of appropriation is not immediately devoted to tho construction of the concrete road ; tiiero are certain ’hies that at the moment do not warrant this form of construction, but upwards of seventyfour per cent, of this huge sum will be expended on the hard surfaced road. It is found by the engineers that where the roads have been built lor some years, where the foundation is dried-out and consolidated with traffic, that over these old metalled roads, after the surface has been broken, the concrete can be very easily laid. It is largely under similar conditions that this construction is replacing the oldei system of using metal as shingle or crushed stone in road construction. Di the formation of a road on a new line complete drainage and the thorough compacting of the foundation are the outstanding features of the practice of road making in the United States. To those who have travelled on these modern highways, there is nothing startling in the statement that the modern highway is in America claimed to be the saviour of rural life.

Wo may then come to tho question■ What is this concrete road? It is a road formed Of clean hard well-graded sand, shingle or pebbles or crushed stone inlaid in proper proportion with Portland cement and water, so laid on a well drained firm foundation, that slabs of about fifteen feet wide? twenty five feet long and about six inches in thickness are formed. These slabs provide a durable hardsurfaced road that makes possible higher speed and larger loads with less tractive power than any other form of highway. It. is a road available for traffic tftree hundred and sixty-five days of the year; it is without dust in jummer or mud in the winter.

The first requirement in the formation of the concrete road is:— Successful concrete road construction demands: Proper preparation of the foundation. This usually •means the thorough drainage of the road-line, to provide that water will not remain under the concreted surface and that the foundation will be so rolled and compacted that there will be no displacement of that surface under the stress of traffic. What does a concrete road cost? America is the only country from which data to include many' miles of concreted highway can be'quoted. Tho average pre-war cost a mile of upwards of eight thousand miles of this form of road is given as two thousand four hundred pounds. The average width of these roads is fifteen feet. What does it cost to maintain these concrete highways? The expenses of keeping a well constructed concrete highway in repair is estimated to range from six pounds to ten pounds a mile, a year. Concrete makes the only road where first cost considered, permanence of construction is closely approached. The cost of maintenance is so small, that after tho interest on the cost of the construction has been provided for, a fund, based on the usual cost of maintaining a metalled road, could bo well established to pftjvide the means to pay off the cost of the first construction. It is fully recognised that no extensive road improvement can be carried out without more money than can be

raised on rates, therefore loans are neqessary to finance these undertakings.* It is fair that this should be so, for the benefits of the concrete highway extend beyond one generation. The benefits of the concrete road:— It reduces the cost of road haulage, by permitting the increase of the load, tlie reduction of the tractive power, and it reduces the time that is required toi transport along the earthen or i>ietslk a road. Tho concrete road benefits the people of a district by making travelling quick, safe, easy and comfortable. It extends tho limits of a neighbourhood. 31 ore people come into personal touch with each other. Social opportunities are increased. The monotony of the isolation of rural life is removed. They bring greater contentment to the young people on the farm. Citjy and country are nearer neighbours. School attendance is increased. A broaded knowledge of life and a higher standard of living developed. it brings greater freedom of movement. It permanently increases land values. All of its benefits are lasting.

Cost of Concrete and Tarred Heads.

Th tho spring of this year tho Otago Motor Club sent Mr. B. B. Coulston, C.E., to the North Island to report on what was being done by tho various County, City. and Borough Councils in respect to modern road construction, and that gentleman presented tho local bodies in Southland and Invercargill with a very comprehensive report, which will bo invaluable to the Government and local authori ties, in the formation of a scheme for

the improvement of the Dominion’s arterial roads under modern methods of construction. In the concluding section of his report, Mr. Coulston, dealing with the cost of concrete and tarred roads, said that there is undoubtedly a considerable range in the price of what appears to be similar methods of construction, and this is partly due to the difference in cost of material and partly to the condition of the road before treatment. A If, however, we take for illustration a road 15ft. m width tho following prices may lie said to represent tho average cost of typical methods:— (a) For tar-painting a well-consoli-dated macadam road in good condition, £3OO to £4OO per mile. (b) For tar-sealing a macadam road that has been brought to good condition not less than six months previous, £6OO to £IOOO per mile. (c) For reconstructing a macadam road with, say. 4in. new metal on old macadam foundation with single or multiple penetration method of tar grouting, £ISOO to £2OOO per mile. , (d) For constructing a tar macadam road of standard thickness with 3in. to 4|in. of tar macadam wearing surfhee, £I6OO to £2400 per mile. (e) For a concrete road Gin. in thickness. £3500 per mile. (f) Carpeting a concrete road Tin. to l|in, of tarred screening, £ffoo per mile.

(g) Annual cost of resealing any of the above roads, £IOO to £l5O per mile.. RELATIVE ECONOMY. z Theoretically the relative economy of the different constructions can only bo expressed by the sum of the first cost and the capitalised cost of maintenance and renewal. But tho general method adopted for comparison is to compute the annual cost per mile, allowing for interest and sinking fund over the number of years which the road is estimated to have life and for maintenance.. Unfortunately, the life of a road and its cost of maintenance can only be approximated because of the unknown factor of fluctuation in amount and class of traffic that inevitably follow the improvement of a road, and because wo are at present in tho transition period from horse-drawn io motor vehicles. Moreover, although theoretically the road giving the lowest annual cost is the most economical one to build, financial considerations more often than otherwise make it necessary to select some other type. It may bo taken for granted that the country highway of the future will vary exceedingly in type, depending on the intensity of the traffic, and will range from the highest form of construction down to the earth road and the gravel and water-bound macadam of the present day. These latter must necessarily contain the largest mileage for many years to come, and the importance of giving greater care and attention to the maintenance of such roads cannot be overstated. Results of observations of different types of road surface have shown that

a good gravel road will wear well with 50 to 70 light teams, 25 to 30 heavy teams with one horse, 10 to 15 heavy teams two or more horses, and 50 to 75 automobiles per day. The waterbound macadam will stand 175 to 200 light, 175 to 200 heavy one horse, 60 to 80 heavy two horse, but not over 50 automobiles at high s|>eed per day, and a good grav?! road will wear well with 50 to 70 light teams. 25 to 30 heavy that water-bound macadam with a good surface coating of tar renewed annually will stand with 1(X) to 150 light, 50 to 75 heavy one horse. 25 to 30 heavy two horse, and 1500 or more automobiles per day. The limiting carrying capacity of gravel roads was repeatedly exceeded iff pre-motor day.', and those roads W'ere then metalled, hut the limit fixed for the macadam road was rarely exceeded. except in cities, until the advent of the motor, and it was for that reason that they so lung served their purpose. On these roads where the limit of 50 cars travelling at high speed is exceeded, we have overwhelm ing evidence that some new form of wearing surface is necessary, and at the present time the choice is practktiby limited to some form of bituminous material and concrete. On many sections of macadam roads where it has become impossible to maintain the wearing surface from gravelling, it has been shown concitlsivcly that a first expenditure of £3OO or £4OO, and an annual maintenance cupt of £lOO to £l5O per mile per annum, or say. taking an average* and giving the road only a life oi five years, an expenditure of less thon£2oo per year will not only give an cxcelleat surface, but entirely save the wear of the macadam foundation. On other sections wh< re tin* traffic is more considerable, or when*. m view of future requirements, a more permanent form of roadway ha* been

thought desirable, a first cost of £6OO to £lOOO in tar-scaling and an annual maintenance cost as before has given a macadam road ar life of 10 to 15 years, and the average, as before, is about £2OO per mile per annum. Setting nside altogether the great advantages derived from the improved surface there can he no question that such a method is more economical than spending £lOO to £l5O on a water-bound macadam road and at that figure being unable to annually replace the worn mete I. When it comes, however, to consideration of a road where nothing short of rebuilding will serve, and where traffic considerations require a more permanent type of pavement, from the point of economy, there is little to choose between the tar macadam and the , t concrete road, as practically the annual costs of combineci interest, sinking fund, and maintenance over a period of years may be assuming different ultimate lives, be shown to be the same. I have purposely qualified the statement. as 1 do not propose in this report to maJce comparison between the two types of construction. The advocates for the concrete roads claim that ut the end of the term the concrete remains as good as ever, whereas the bituminous macadam would require rebuilding. The advocates fcr the bituminous road argue that by annually re sealing the life of the road is indefinite, and even if the road required rebuilding old macadam could be used fur foundation. % My mission was to collect data. not< to point the moral. Both types of construction represent so marked an improvement on tnenner methods that H is invidious to draw comparisons.

ROAD TRAFFIC CONTROL. My report is incomplete without soinu reference to the* question oi toad traffic control. One of the resolutions passed at the* International Roads Congress was:--"That all regulations lor the control of road traffic should la* bused on the* principle «:f allowing the speed practicable to each different kind of vehicle, consistent with pul In sale ty and general uonveuicucc. and the normal wear of the road." In New Zealand local bodies are empowered to regulate what might be termed light traffic* on the first named principle only, that is. consistent with public safety and general convenience, and they may, if thought advisable lor the safely <d the public , prohibit the use of a road or portions oi it tor motor traffic jiltogeth *r. W ilh regard to heavy traffic, they are given greater powers, and although it is not so expressed in the statute, the underlying principle is regulating such traffic to ‘*tho normal wear oi the* road. but the jxiwcr of uontrui is practical ly limited to the winter months oi the year. 1 bold that all traffic, whither heavy or light, should Im* subject to regulation. The question of the extent to which and under what conditions, roads are damaged by motors, has A>c-

copied a: prominent place in all recent discussions on road problems, and where it has been established that substantial damage has been occasioned, by these vehicles, fjie reasons for the damage arc* well understood, and it is. ''generally agreed that the effect of self propelled vehicles is only more damaging than those drawn by horse when the road is unsuitable for the use ofc' such vehicles. Light motor cars do little damage to. roads when the surface is smooth and. sealed with some waterproof coating, such ns tar. Neither do they appreciably damage a well-formed day or closegravel road. On well made water-bound macadam roads with smooth and even surface there is little damage, with one important stipulation — namely, that the cars are driven at a moderate speed. But very considerable damage takes place on this class of road when subjected to a considerable amount of motor traffic driven at high speed. The damage is caused by the removal of the' small, gritty particles of stone forming the binding. which serves to keep the surface stones in place, and takes place more particularly in summer, when the roads are dry. There small particles arc* not, as is popularly supposed, icmoved by the suction of th<* pneumatic tyre, but by the shearing action caused by the driving w heels of the car. The shearing or tractive force tends to tear the tsuiface, thus looseninig the gritty particles forming the bond between the stones. The damage is greater if the road is out of repair and the surface uneven, the force* of the impact of the whorls in the hollows causing depressions to beaome deeper, especially during wot weather, when these depressions contain water.

Heavy motor vehicles, especially those shoti with metal tyres, are « great source’of damage, not only to weak macadamised, hut. unlike the light motor car. also to gravelled roads. I his damage is caused by shearing and impact. Hie effect of shearing is due to the tractive force of the driving "heels. and the damage is proportionate to the weight and speed of the vehicle, while the force of impact, or the pounding force, increases with the square oi the velocity. For example, it one vehicle carrying a load of five tons travels at a speed of four miles an hour, and another similarly constructed and loaded, travels at the rate of 12 miles an hour, the force of the wheel impact, and consequent I v the damaging effect upon the road, will bp in the ratio of 1 to 9. Damage from impact does not occur to any appreciable extent with pfieumatic tyres. The fact L* now conceded that ordinary macadam roads are not suitable to withstand the continuous traffic* that may be expected in the vicinity of populous centres of either light high speed traffic or heavy motor vehicles fur commercial purposes. But when it is considered that ordinary macadam will, for reasons of economy and force of circumstances, Ik? the material upon which reliance will have to be placed for the construction of many of our country roads, it is more desirable to regulate the traffic which use these reads before they suffer serins damage than to legislate after the damage has taken place. Only on certain main thoroughfarefl radiating from the city and carrying a considerable motor traffic, it is rea-

sonable to expect that any special provision will he made in the near future to render them suitable for and less loablc to damage by motor traffic. In outlying districts it would not onl\ be wastehil to construct roads to a standard above present traffic requirements. but an injustice to tho many backblock settlers who would welcome a metalled road of any description as a luxury. 'Huse t» are not made with a view to discouraging or undulv rest! h ting t| h; use o| motor vehicles. .inn these* days have liecome a neccssit.v tor pleasure as well as for business IHiiinsi's. but to advocate that all rea--•"imble means be employed which have the etfe-1 ot reducing the damage to roads by excessive speed in the case "I light motor cars, or by excessive loading or defective design of heavv commercial vehicles.