A History of Inland Transport and Communication in England. Edwin A. Pratt
Cheshire and Derby, rendering an 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 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 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.
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 1½ 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 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