CHAPTER XII SCIENTIFIC ROAD-MAKING
发布时间:2020-07-06 作者: 奈特英语
One question which naturally arises in connection with the turnpike roads is, "Why was it, when there was so widespread an organisation of turnpike trusts, and when so much money was being spent on the repair of the roads, that the roads themselves were still so defective, and only relatively better than they had been before?"—this being the real position, notwithstanding the praises bestowed on the turnpike system by those who were gratified with the stimulus given to trade, travel and commerce by the improvements actually made.
The answer is that although a vast amount of road-making or road-repairing was going on, at the very considerable expense of the road users, and to the advantage of a small army of attorneys, officials and labourers, it was not road-making of a scientific kind, but merely amateur work, done at excessive cost, either with unintelligent zeal or in slovenly style, and yielding results which mostly failed to give the country the type of road it required for the ever-increasing traffic to which expanding trade, greater travel, and heavier and more numerous waggons and coaches were leading.
Before the adoption of scientific road-making, the usual way of forming a new road was, first to lay along it a collection of large stones, and then to heap up thereon small stones and road dirt in such a way that the road assumed the shape of the upper half of an orange, the convexity often being so pronounced that vehicles kept along the summit of the eminence because it was dangerous for them, especially in rainy weather, to go along the slope on either side.
This form of road was adopted in order to ensure good drainage for rain-water; and in this connection the writer on "Roads" in Postlethwayt's "Dictionary" (1745) says:—
"The chief and almost the only cause of the deepness and {99}foulness of the roads is occasioned by the standing water which, for want of due care to draw it off by scouring and opening ditches and drains and other water courses, and clearing of passages, soaks into the earth, and softens it to such a degree that it cannot bear the weight of horses and carriages."
But the result of making roads in the shape of a semicircle was that the central ridge was speedily crushed down, and ruts were formed along the line of traffic passing over the loose materials used. These ruts, again, defeated the purpose of the original high convexity by becoming troughs for the retention of rain and mud, the latter being rendered worse with each fresh churning up it received from the wheels of waggon or stage-coach.
The road-maker thus required to be speedily followed by the road-repairer; and his method of procedure has been already indicated in Arthur Young's description of the road to Wigan, where he says, "The only mending it receives is the tumbling in some loose stones, which serve no other purpose but jolting a carriage in the most intolerable manner."
The mending of hundreds of miles even of turnpike roads had never gone any further than this. There was no cohesion in collections of loose stones, mainly in their natural and more or less rounded form, and the expectation that they would be crushed and consolidated into a solid mass by extra-broad waggon wheels, in accordance with Acts of Parliament in that case made and provided, remained unfulfilled. The stones were simply displaced and thrown aside by the traffic, the inevitable ruts reappearing in due course; while, as the rainwater passed readily through them, the roads became elongated reservoirs of water in rainy weather, and were most effectively broken up by frost in winter.
It was from conditions such as these that Thomas Telford and John Loudon McAdam came to rescue the country.
There had been one road-reformer before them, in John Metcalf, a native of Knaresboro', where he was born in 1717. Though totally blind from the age of six, he developed abundant resources, and became successively fiddler, soldier, chapman, fish-dealer, horse-dealer and waggoner. Taking at last to road-making, he constructed about 180 miles of road in Yorkshire, Lancashire, Cheshire and Derby, rendering an {100}important service to the two first-mentioned counties, more especially by improving their means of communication at a time when they were greatly in need of better roads on account of their then rapidly increasing trade and industry. But though Metcalf did good work in these directions, and achieved some noteworthy successes in carrying solid roads across difficult bogs, he introduced no really new system, and the chief progress made did not come until after his death, in 1810.
Son of a shepherd at Eskdale, Dumfriesshire, where he was born in 1757, Telford started life as a stonemason's apprentice, but became an engineer, and undertook many important works, including canals, bridges, harbours and docks. Here, however, we are concerned with him only as a builder of roads—a department in which he showed great skill and activity.
On the appointment, in 1803, of a body of Commissioners who were to improve the system of communications in Scotland (one half of the expense being defrayed by Parliamentary grants, and one half by local contributions), Telford was selected to carry out the work, and he constructed 920 miles of road and 1,117 bridges in the Highlands, and 150 miles of road between Glasgow, Cumbernauld (Dumbarton) and Carlisle. Then, in 1815, money having been voted by Parliament for the improvement of the Holyhead road, with a view to the betterment of communications with Ireland, Telford was entrusted with the task, which involved the making or improvement of, altogether, 123 miles of road.
Telford's own opinion of the roads of England and Scotland was thus expressed in the evidence he gave before the select Committee of the House of Commons in 1819:—
"They are in general very defective both as to their direction and inclination; they are frequently carried over hills, which might be avoided by passing along the adjacent valleys ... there has been no attention paid to constructing good and solid foundations; the materials, whether consisting of gravel or stones, have seldom been sufficiently selected and arranged; and they lie so promiscuously upon the roads as to render it inconvenient to travel upon them.... The shape of the roads, or cross section of the surface, is frequently hollow in the middle; the sides incumbered with great banks of road dirt, which have accumulated in some places to the height {101}of six, seven, or eight feet; these prevent the water from falling into the side drains; they also throw a considerable shade upon the road, and are gross and unpardonable nuisances. The materials, instead of being cleaned of the mud and soil with which they are mixed in their native state, are laid promiscuously upon the road."
In planning new roads Telford cut right through the hills, wherever possible, in order to avoid unduly steep gradients. In making the roads he first arranged a solid foundation of pieces of durable stone, from 4 in. to 7 in. in size, these being carefully put into position by hand, with the broadest side downward, and packed with small stones in between. On the rough pavement thus formed he laid an upper course of small broken stones, with a binding of one inch of gravel. Between the two courses a drain was set across the road every hundred yards, Telford attaching great importance to the carrying off of all water that might percolate through the upper course on to the lower. He gave a uniform and only moderately convex shape to the surface of the road, abandoning, in this respect, the ideas of his more amateur predecessors. But his system was one that called for much labour and care, as well as for an abundant supply of the needful materials, and the cost of carrying it out was proportionately high, if not, in some situations, prohibitive.
McAdam preferred to be considered a road-repairer rather than a road-builder, and his methods differed materially from those of Telford. He became, also, much more of a propagandist in the work of road-improvement, enforcing his theories with such success that he brought a new word into the English language, roads made or mended according to the main principles he laid down having been known ever since his day as "macadamised."
Born in Ayrshire in 1756—one year before Telford—McAdam went to America at the age of 14 to start life in the counting-house of his uncle in New York. Subsequently he became a successful merchant, and returned in 1783 to Scotland, where he bought the estate of Sauchrie, and then, in 1785, began to devote his attention to road-making, which was to occupy his thoughts and absorb his energies for the rest of his days. Roads he came to regard as, in his own words, "perhaps the most important branch of our domestic {102}economy." Many new roads were then being constructed in Scotland, and he himself became a commissioner of roads in that country. He also began a systematic course of travel over the roads of England and Scotland, covering, by 1814, no fewer than 30,000 miles.
In 1810 McAdam commenced a series of experiments in the construction of roads, and he published the following year some "Observations on the Highways of the Kingdom," recording the opinions he had formed as the result of his twenty-seven years' inquiries.
By this time the question had, indeed, become acute. The prosperity of the country had undergone much expansion, but the improvement of the roads, notwithstanding the extension of the turnpike system, had in no way kept pace with the general progress and the growing needs of the nation. Parliamentary Committees were still devoting close attention to that good old stock subject, the width of cart-wheels. In 1806 there was a select Committee appointed "to take into consideration the Acts now in force regarding the use of Broad Wheels, and to examine what shape is best calculated for ease of draught and the Preservation of the roads." This Committee presented two reports, and like Committees were appointed in the Sessions of 1808 and 1809, each of these Committees making three reports. What Parliament itself was doing at this period in the way of cart-wheel legislation has already been told.
So there was abundant scope for the activities of someone who could offer new ideas, and when, in 1811, a select Committee was appointed "to take into consideration the Acts in force regarding the Highways and Turnpike Roads in England and Wales, and the expediency of additional regulations as to the better repair and preservation thereof,"[16] McAdam came forward with his proposals, as contained in the aforesaid "Observations" presented by him to the Committee in question.
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McAdam began by saying that "In all three reports of Committees of the House of Commons on the subject of roads, they seem to have principally in view the construction of wheeled carriages, the weights they were to draw, and the breadth and form of their wheels; the nature of the roads on which these carriages were to travel had not been so well attended to." Proceeding to give the results of his own investigations, he expressed the view that the bad condition of the roads of the kingdom was owing to the injudicious application of the materials with which they were repaired, and to the defective form of the roads; and he assured the Committee that the introduction of a better system of making the surface of the roads, and the application of scientific principles which had hitherto never been thought of, would remedy the evil.
The basis of his system, as defined on this and subsequent occasions, was the covering of the surface of roads with an impermeable crust, cover or coating, so that the water would not penetrate to the soil beneath, which soil, whatever its nature, and provided it was kept dry, would, he argued, then bear any weight likely to be put upon it.
His method of securing the said impermeable crust was by the use of an 8 in. or 10 in. covering of broken stones, these being not more than about 1? inches each in size, or more than about six ounces each in weight. Such broken stones, if properly prepared and properly laid on a road, would, he showed, consolidate by reason of their angles, and, under the pressure of the traffic, be transformed into a "firm, compact, impenetrable body," which "could not be affected by vicissitudes of weather or displaced by the action of wheels." The broken stones, with their angular edges, would, in effect, dovetail together into a solid crust under a pressure which, applied to pebbles or flints, would merely cause them to roll aside, in the same way as shingle on the seashore when passed over by a cart or a bathing van.
The difference between his broken stones and the more or less rounded stones with which the roads were then being repaired was, McAdam declared, the difference between the stones that were thrown down in a stream to form a ford and the shaped stones used to construct the bridge that went over the stream; while inasmuch as the road-arch, or crust, he {104}formed would rest on the ground, and be impermeable to rain-water, there would be no need to have underneath it either a stone foundation or a system of drainage; though he held it as essential that the subsoil should be perfectly dry when the "metal," or covering of broken stone, was laid in position. Keeping the water out of the road by this means, he would prevent the road itself from being broken up by the action of frost, and he would have a more elastic surface than if there were a solid stone foundation under the metal. The thickness of his consolidated cover of broken stones would, he further argued, be immaterial to its weight-carrying capacity.
In 1816 McAdam became surveyor of roads in the Bristol district, and the object lessons in road-mending which he provided there were so convincing that his system began to be generally approved in 1818. In 1827 he was appointed Surveyor-General of Roads, and in the same year he issued a ninth edition of his "Remarks on the Present System of Road-Making."
In this publication he states, among other things, that very considerable sums were being raised annually in the kingdom, principally from tolls, on account of turnpike roads, and these funds were expended, nominally under the protection of Commissioners, but practically under the surveyors. Every Session there were numerous applications to Parliament by turnpike trusts for powers to increase their tolls in order to pay off their debts and to keep the roads in repair. In the Session of 1815 there were 34 such petitions; in 1816 there were 32, and "all passed as a matter of course." The condition of the turnpike roads was, nevertheless, most defective, and that of the parish roads was "more deplorable than that of the turnpike roads." Legislative enactments for the maintenance and repair of the parish roads were so inadequate that these roads "might be considered as being placed almost out of the protection of the law." In the result "The defective state of the roads, independent of the unnecessary expense, is oppressive on agriculture, commerce and manufactures by the increase of the price of transport, by waste of the labour of cattle, and wear of carriages, as well as by causing much delay of time."
As for Scotland, he declared that "The roads in Scotland are worse than those in England, although materials are more {105}abundant, of better quality, and labour at least as cheap, and the toll duties are nearly double; this is because road-making, that is the surface, is even worse understood in Scotland than in England." He mentions that the Postmaster-General had been obliged to give up the mail-coach from Glasgow to Ayr on account partly of the bad roads and partly of the expense, there being ten turnpike gates in 34 miles of road.
The roads were, in fact, McAdam continued, "universally in want of repair." Ample funds were already provided; but the surveyors employed by the turnpike trusts were "mostly persons ignorant of the nature of the duties they are called on to discharge,"[17] and the money brought in by a continual and apparently unlimited increase of the tolls was "misapplied in almost every part of the Kingdom." In some new roads made in Scotland the thickness of the materials used exceeded three feet;[18] but, said McAdam, "the road is as open as a sieve to receive water"; and what this meant he was able to show by pointing to the results of weather conditions on bad roads in the month of January, 1820. A severe frost was succeeded by a sudden thaw, accompanied by the melting of much snow, and the roads of the kingdom broke up in an alarming manner, causing great loss, much delay of the mails, and endless inconvenience. The cause of the trouble was explained by McAdam thus:—
"Previous to the severe frost the roads were filled with water which had penetrated through the ill-prepared and unskilfully-laid material; this caused immediate expansion of the whole mass during the frost, and, upon a sudden thaw, the roads became quite loose, and the wheels of the carriages penetrated to the original soil, which was also saturated with water, from the open state of the road. By this means many roads became altogether impassable."
On the 1000 miles of road to which his own system had {106}been applied there had, he further said, been no breaking up at all by reason of frost.
The figure here given suggests the extensive adoption of McAdam's system which was then proceeding. It was not only that old roads were being repaired according to his plan, but there was much construction of "macadamised" roads, the deficiencies of the existing roads having discouraged and checked the provision of new ones. Between 1818 and 1829, as told by Porter, in his "Progress of the Nation," the length of turnpike roads in England and Wales was increased by more than 1000 miles. In proportion, also, as the turnpike roads increased alike in number and in quality, through the wider adoption of McAdam's system, there was a corresponding impetus given to coaching in respect both to number of vehicles and to increase of speed, leading up to those "palmy days" of coaching which were only to close with the spread of the railway.
It is true that McAdam's plans were not adhered to exactly as he first laid them down. Greater experience led later authorities to attach more importance to a foundation than McAdam had been disposed to do; though they did not necessarily have foundations laid by hand, after the manner of Telford's buried pavements. Later, the introduction, also, of the steam-roller was to revolutionise the art of making macadamised roads.
Nor can it be disputed that McAdam and Telford had both, to a certain extent, been anticipated. In an article on roads published in the "Quarterly Review," in 1820, the observation is made in respect to them that "Many of the practices of each of these gentlemen had been previously adopted in a variety of instances; but it required zeal and perseverance like theirs to recommend the entire system to the attention of the public."
Other persons might have recommended the use of broken stones, and these are said to have been already employed in Switzerland before McAdam came on the scene; but it was his lucid explanation of the scientific bearing of angular as opposed to round stones; his untiring zeal in travelling thousands of miles over English and Scottish roads in order to see and study everything for himself; and his advocacy of scientific road-making with such indefatigable energy, though {107}to his own impoverishment (until Parliament voted him recompense), that led to the conspicuous and world-wide success his system eventually attained.
Writing in 1826, "Nimrod" said: "Roads may be called the veins and arteries of a country, through which channels every improvement circulates. I really consider Mr McAdam as being, next to Dr Jenner, the greatest contributor to the welfare of mankind that this country has ever produced."
This may seem, to-day, to be exaggerated praise; but if the reader looks at the matter from the point of view from which "Nimrod" himself must have regarded it, and tries to realise how greatly the deplorable state of the roads—before McAdam began to repair them—was hampering social life, travel, trade, commerce and national industries, he will probably conclude that such praise, at such a period, and in such circumstances, was far from being undeserved.
The turnpike system lasted well into the railway period, and the story of its gradual decline and the causes that led thereto has still to be told. Before, however, dealing further with these aspects of the general question I propose to revert to the subject of rivers and river navigation; to show, next, how canals and canal transport were developed; and then to give an account of the rise of that railway system which was so materially to affect alike rivers, canals and turnpike roads as well.
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