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well-made pavement, quite horizontal, it appears, from the experiments made with Mr. Macneill's machine, that the resistance to draught is not more than the 100th part of the weight of the carriage and its load, when the carriage is properly constructed, and mounted on straight and cylindrical axles.* According to this, a horse of great power would be able to draw on such a road, if horizontal, six tons and three quarters; and if with no greater inclination than 1 in 50, two tons and a quarter.
The same experiments show that the tractive force on a good pavement is 33 lbs., while that on a broken stone road is 65 lbs., and that on a gravel road 147 lbs.
The following statement on pavements is taken from the evidence of Mr. Walker, given before a select committee of the House of Commons, upon the Commercial Road from London to the West India Docks :
“It is not, I am sure, overstating the advan. tages of paving, but rather otherwise, to say, taking the year through, two horses will do as much or more work with the same labour to themselves upon a paved road than three upon a gravelled road, if the traffic on the gravelled road is considerable ; and if the effect of this is brought into figures, the saving of the expense of carriage will be found to be very great when compared with the cost of paving. If the annual tonnage upon the Commercial Road be taken at 250,000 tons, and at the
* See Mr. Telford's Seventh Report on the Holyhead Road.
rate of only three shillings per ton from the Docks, it could not, on a gravel road, be done under four shillings and six-pence; say, however, four shillings, or one third per ton difference, which makes a saving of 12,5001. in one year.
“I think I am under the mark in all these figures; and I am convinced, therefore, that the introduction of paving would, in many cases, be productive of great advantages."
Mr. Walker further says, that “ during thirteen years that the East India Docks' branch has been paved, the paving has not cost twenty pounds in repairs, although the waggons, each weighing about five tons, with the whole of the East India produce, which is brought from the Docks by land, have passed all that time in one track upon it; and a great deal of heavy country traffic for the last eight years, when a communication was formed with the county of Essex.”*
This road has been referred to, not by way of showing a perfect specimen of pavement, but generally to point out the advantages of paved roads; for this road, in consequence of the plan of Mr. Walker not having been strictly attended to, was by no means originally constructed in so perfect a manner as it might have been.
Still, however, it was by far the best specimen of pavement that had been executed; and it has fully established, by experience, the great advan
• See Report of the Committee of the House of Commons on Turnpike Roads in 1819.
tages which the public may obtain by making a paved road for transporting merchandise, when it is not possible to make a canal or railway.
A common opinion prevails, that because paved streets have almost every where been suffered to be rough and imperfect, all pavements must necessarily be rough and bad ; but a slight degree of consideration will show that this opinion is without foundation, and that, in point of fact, the cause of rough and bad pavements is bad management, arising from the ignorance of those employed to make them, or the want of sufficient funds for executing good work.
The chief defects of all pavements arise from neglecting to give the stones a proper shape, and to construct a substantial foundation to support them.
The foundation for the London pavements has commonly been formed with all sorts of old rotten materials, without having uniformity in texture or solidity.
This makes the bottoming of unequal strength, and the consequence is, that after the pavement has been laid upon it, the weaker parts give way, while the stronger remain firm, so that the surface of the street becomes low in some places, and high in others, and very soon rough and out of order.
But the effect of this bottoming is visible in another way; for in consequence of the defective shape of the stones, and also of the defective manner in which they are set, there is a quantity of soft earth between them, which serves to conduct the water which falls on the pavement through the joints of the stones into the body of earth that lies under them. But when the water gets into this earth, it forms a bed of mud, and the heavy weights passing over the paving-stones press them into it, and then the mud, not being able to resist the pressure, rises upwards between the joints to the surface of the pavement.
In making some of the new pavements in London, more attention has been paid to the foundation than formerly, but still not so much as there should have been. Fleet Street, for instance, was paved with considerable care; the stones were properly shaped and dressed, and evenly laid: the ground was dug out twelve or eighteen inches deep, and a body of broken stones was put into the space thus cleared out for a foundation, and the joints of the paving-stones, when set, were grouted with liquid lime. Yet, notwithstanding all this, the pavement soon got out of order, and became uneven and extremely defective in a few months after it was. made. The cause of this failure was that the stones for the foundation were thrown in loosely, by cartloads at a time, and merely levelled before the paving-stones were laid on.
The great defects in the London pavement, with respect to the shape of the paving-stones, and to proper bottoming, are, in a great measure, to be attributed to the errors committed by the persons who have had the management of making contracts for it. They have acted too much on the principle of
getting cheap work, and to accomplish this have neglected the main point of securing good work. In this way they have promoted a system of inconsiderate competition, and thereby reduced the price of paving work so unreasonably as to make it impossible for contractors to provide the best materials, and to bestow the necessary portion of labour on dressing and setting them, without loss.
Besides this, the managers of the pavements have sometimes committed another error, in requiring the contractors to execute their work by the superficial square yard, of a certain depth, without adding conditions respecting the weight of the stones to be put into a square yard, and without requiring the close joining of the stones. As contractors purchase the stones by weight, the less square (that is, the more imperfect) they are, the more profit they will have on each superficial yard; so also in proportion as the joints between the stones are wide, fewer stones will be used, and the work will be proportionably profitable to them, and defective for the use of the public.
Having thus shortly explained the principal defects of the London practice of paving, the mode that seems fit to be adopted in its stead shall now be described.
The first object to be secured is a good foundation. In those streets where there is a constant passing of carriages, both night and day, such as the Strand, Fleet Street, Holborn, Cheapside, Piccadilly, and Oxford Street, the foundation for the pavement should be a sub-pavement made of old