Remarks on the Present System of Road Making / With Observations, Deduced from Practice and Experience, With a View to a Revision of the Existing Laws, and the Introduction of Improvement in the Method of Making, Repairing, and Preserving Roads, and Defending the Road Funds from Misapplication. Seventh Edition, Carefully Revised, With an Appendix, and Report from the Select Committee of the House of Commons, June 1823, with Extracts from the Evidence

by John Loudon McAdam

[2]. The increase of the breadth of the wheels, though in a greater proportion than that of the weights, is by no means a compensation for it; because the whole breadth in many instances, from the inequality of the ground, or the wheels, will not be brought to bear whenever it can, the first impression must be made by the nails, where they are prominent, perhaps by a single nail; or the bearing may happen upon single pieces of materials, or upon the edges of materials, incapable of supporting the weights. See Enquiry into the State of the Public Roads, by the Rev. Henry Homer, A. M. Rector of Birdlingbury, Warwickshire. Published in 1767, Page 66.

It must be observed, that these remarks of Mr. Homer, and of every other writer on the subject of roads, are only applicable to such as are loose, rough, and uneven; and that no one seems to have contemplated the idea of a road being made at once strong, smooth, and solid.—Author.

[3]. Broad-wheeled carriages are found to be so unadapted to the purposes of husbandry, the number of horses requisite for their draught so great, and the beneficial effects of them to the road so questionable, that neither the encouragements on the one hand, nor the discouragements on the other, have been sufficient to bring them into general use.

Homer’s Enquiry, Page 25.

It must however be admitted, that the wear of roads is proportioned to the weight and velocity of carriages running upon a given breadth of the tire of the wheels, and therefore, it is of consequence that some regulations should be adopted. The best regulations, as regard the breadth of the tire of wheels, will be found in several Acts of the Session of Parliament 1816, where Carts are required to have wheels of a cylindrical form five inches broad; and Waggon Wheels of the same form six inches broad, with an equal upright bearing. The weights will be best and most easily regulated by the number of horses, or other cattle, drawing the carriages: and this, as a regulation of economy, may be made, by the tolls at present payable on the cattle being levied in a larger ratio as the number increases.

Waggons and carts with wheels of a cylindrical form and upright bearing, running on a breadth of tire of five and six inches, cannot injure a well made road, at the slow pace with which such carriages travel; at least, in any proportion beyond the toll they pay. On the contrary, it is certain, that Stage Coaches, with their present system of loading, and velocity of travelling upon very narrow wheels, damage the roads in a much greater proportion than the compensation derived from the toll.

Every wheel, propelled by a force applied to its centre of motion, as the axis of a carriage wheel, is disposed by its specific gravity, to be dragged forwards, instead of turning round; and the rotative motion is occasioned by the resistance presented by the surface over which it passes; yet this resistance does not entirely prevent dragging; for every wheel running upon a road drags in some degree. This degree will be proportioned to the weight of the carriage, and the velocity of the wheel upon its axis, and will be opposed by the breadth of the tire coming in contact with the road.

Stage Coaches, therefore, carrying heavy weights, moving with great velocity, and presenting to the road a narrow tire of wheel, must of necessity drag in a greater degree than any other carriage, as combining in themselves every cause by which dragging is produced.[^[4]]

[4]. Above fifty Stage Coach journies are made daily between Bristol and Bath: the Author’s observation leads him to the conclusion, that the toll-duty paid by them, does not indemnify the funds for the wearing of the road.

When the Legislature shall have provided the means of putting all the roads in the United Kingdom into the best and fittest state for the accommodation of the agriculture and commerce of the country, they will naturally consider of the most proper modes of protecting them from injury, or for indemnifying the funds for the effects of use which are unavoidable, by imposing toll duties in a just and equitable proportion on the carriages occasioning such injury.