Page images
PDF
EPUB

off any

a

as an under drain to carry

any

water that may pass through the surface of the road. The component stones of the pavement, having broader bases to stand upon than those that are broken small, are not so liable to be pressed into the earth below, particularly where the soil is soft. The expense of setting this pavement is less than one fourth of that of breaking an equal depth of stones to the size generally used for upper coating; and therefore, in point of economy, it has also a material advantage.

“ Mr. Telford, in all cases recommends this paving; and the opinion of a

of a man of such experience cannot be treated slightly. He has made more miles of new road than any engineer in the kingdom ; and having myself studied for nearly fifteen years in his school, and made a considerable extent of road under his direction, I may venture to say that his practice is not unsupported by experience.

" I should not have said so much on this subject, but from the circumstance of other road improvers having asserted that paving was useless ; and I think that assertions on one side should be met with firmness on the other, whenever an important principle is attacked, the correctness of which can be established by reasoning and by facts.

for four years;

“Whenever any new piece of road has been made, I have taken care that a good bottoming should first be put under the broken stones, because I am satisfied that it makes the road more substantial, and is also less expensive. Some of the new road made on this principle by the Commissioners under the Act of 55 Geo. III. has now been travelled

upon

and its present perfect state, I have no doubt, is owing to the firm foundation which was laid under the broken stones. I must refer to my last Report for further particulars of its advantage ; but as I did not then notice the comparative expense of the two modes of road-making, it is proper to state it here, in order to justify the course I have adopted.

Supposing the materials are stone, to be quarried, and carted, say, a quarter of a mile on an average; that the stoning shall be in both cases sixteen feet wide; that, by Mr. Telford's mode, the bottoming shall be seven inches thick in the middle, and five inches at the sides, and the broken stones six inches in uniform thickness; and that by the other mode there shall be no bottoming, but ten inches in depth of broken stones.

“ The expense of a lineal yard on Mr. Telford's principle will be as follows:

S. d.

Quarrying 14 cubic yards of stone (measured on the road) at 1s. 8d.

2 11 Carrying 19 ditto — 1 mile on an average at 6d.

0 103 Setting the bottom

. 0 2 Breaking the top 6 inches $ cube yard at ls. 6d.

1 4

5 3}

The expense of a lineal yard without bottoming would be

[ocr errors][ocr errors]

Quarrying and carrying & of the above

quantity of 1 cubic yards of stone Breaking 10 inches in depth 1} yards

at 18. 6d.

2 3

5 5

“ But if there were plenty of loose stones to be had without quarrying, which is very often the case, the expense per yard, with bottoming, would be,

[blocks in formation]

Carriage of 1 cubic yards
Setting the bottom and breaking the top

as before

1 6

2 41

“ Without the bottoming it would be —

S. d.

Carriage of 5, the last-mentioned quan

tity Breaking 10 inches as before

0 81 2 3

2 113

“ The first of these cases shows a saving of 1ļd., and the latter of 7d. per lineal yard in favour of the bottomed road, a saving which of itself would not weigh much ; but, as the bottomed road is the most substantial and durable, it adds one more to its other advantages.” *

. The following are extracts from Mr. Telford's first Annual Report on the Holyhead Road, May 1824 ; and from his sixth Annual Report, May 23. 1826:

“ Besides the advantages of easy inclinations, ample

We shall conclude our remarks on the necessity of providing a proper foundation for a road by giving a description of the new Highgate

breadth, perfect drainings, and complete protection, the forming of a smooth hard surface is one of the distinguishing characteristics of this new road. In summer it is not dusty, and in winter it is very seldom dirty ; frosts and rains produce but trifling and superficial effects upon it. During the unusually severe frosts of the winter 1822–1823, and the subsequent thaws and heavy rains, the new road was not cut up or rutted in a single instance, though in several parts of the old road, even where it had been put into decent repair, it was too weak to stand such hard tests: it broke up and became as bad as a bog. This breaking-up was not confined to parts of the Holyhead road, but was the case, and to a much greater extent on many, and perhaps all the roads of the neighbourhood. In fact it seemed to be almost universally the case on all roads not constructed with strong foundations, and particularly where the substratum was clayey and retentive of water.

“ The great superiority which the Holyhead new road evinced at that trying time, was doubtless owing to the substantial foundation which had been prepared for it, previous to the upper stratum of broken stones being laid on it. This foundation is a regular close pavement of stones, carefully set by hand, and varying in height from eight to six inches, to suit the curvature of the road ; these stones are all set on edge, but with the flat one lowest, so that each shall rest perfectly firm. The interstices are then pinned with small stones;

and care is taken that no stone shall be broader than four or five inches, as the upper stratum does not bind upon them so well when they much exceed that breadth. The pavement thus constructed is quite firm and immovable, and forms a complete separation between the top stratum of

« PreviousContinue »