1842.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



345 



MR. VIGNOLES' LECTURES ON CIVIL ENGINEERING, AT THE 

 LONDON UNIVERSITY COLLEGE. 



SECOND COURSE — LECTURE XII. — R.\1LWAY ESTIMATES. 



Tms lecture had reference to the consideration of estimates, as applied to 

 raihvays — that is, to ascertain lineal dimensions, superficies, and cubic con- 

 tents, and, affixing the proper rateable prices, to work out the monied results. 

 The Professor said, that, probably, the most ready way to give a general idea 

 on this subject would be to go briefly over the several heads to be considered 

 in framing an estimate. It was assumed that proper plans and sections of 

 the work had been prepared in a skilful manner beforehand, Mr. Vignoles 

 strongly insisting on the necessity and importance of having all such docu- 

 ments furnished on a much larger scale, and with vastly more attention to 

 accuracy and detail, than had often hitherto been the case, particularly for 

 Parliamentary estimates, observing, that erroneous data and calculations 

 could not but result from a neglect of this rule : and. he stated, that, al- 

 though many of the standing orders of Parliament were annoying in some 

 respects, yet the principle on which they were framed, went to compel a 

 compliance with forms, in doing which, greater previous investigation and 

 accuracy of plans and sections, became absolutely indispensable. 



The quantiiij of land required formed naturally the first item of an estimate. 

 It was but seldom, indeed, that the very small economy of taking land for 

 one line of railway only was adopted. To a given breadth, therefore, for a 

 double line — say, from eight to ten yards — must be added the necessary 

 allowance for fencing and ditching — say, three yards on each side — making a 

 constant breadth of fourteen to sixteen yards of land throughout, indepen- 

 dent of the necessary slopes in excavations and embankments ; the additional 

 quantity for these, depends, of course, on the depth of the cutting, or height 

 of the bank, in the various places, and on the ratio of the slopes of the 

 earthwork. Suppose, in a cutting or banking of ten feet, this ratio to be one 

 horizontal to one perpendicular, then, such slopes of one to one require ten 

 feet additional breadth of land on each side — together, tw'enty feet — viz., 

 twice the depth or height to be added as a further breadth, beyond the 

 constant one for the railway and fencing. In like manner, for slopes of one 

 and a half, two, two and a half, or three to one respectively, multiply the 

 varying depths or heights of cutting or embanking by three, four, five or six, 

 as the case may be, for the necessary augmented breadth of land due to the 

 slopes, along their several extents; and thus, from the lengths measured, 

 and the heights figured, on the section, the varying quantities of land are 

 obtained, multiplying length by breadth, and reducing the areas to acres and 

 parts for agricultural districts, and to square yards for land in towns and 

 their immediate vicinities. For the prices to be assigned to these superficial 

 quantities, the engineer must depend on the land valuer, who is also to judge 

 of the amount of contingent damages. On an average, the actual quantity 

 of land for a double line of railway, including the slopes of earthwork, may 

 be taken at ten acres to the mile, but the precise areas must be ascertained in 

 detail in the way explained. The cost of land for many of the leading lines 

 of railway had been as much as £5000 per mile for the whole of their 

 length. The cost of land for lines at a greater distance from the metropolis 

 was less— still, from the numerous contingent after-charges, in respect of 

 land, the sums were large, and had often far exceeded the original estimates. 



The fencing of the land comes within the province of the engineer, though 

 it is sometimes comprised in the item of land. The mode of fencing must 

 always be regulated upon the custom and materials of the country. Dry- 

 stone walls, earth mounds with furze hedges, posts and rails, quickset 

 hedges, and broad side-ditches or drains, are the principal kinds of fencing 

 through agricultural lands ; walls of brick or masonry, set in mortar, are 

 generally called for through towns or building land. The several lengths of 

 each of these are ascertained from the plans ; the prices are obtained in the 

 localities. Including farm gates, the cost of fencing varies from Is. tid. to 

 3s. per yard lineal in the country. In the vicinity of towns, for stations. Sec. 

 the price will vary from 5s. up to 10s. per yard, according to circumstances, 

 ■vhich it must be the business of the engineer to ascertain. 



The third item is usually that of Earthwork— thui is, to reduce the undu- 

 lating natural surface of the ground to the railway level or gradient, by 

 cutting through hills, and filling across valleys. Mr. Vignoles having, in 

 the first course, entered at large into the consideration of earthwork, thought 

 It unnecessary to say much here. The price of the earthwork depends ab- 

 stractedly on the average work that an able-bodied man can perform in a 

 day, in various soils— this it should be the study of the engineer to deter- 

 mine. The mere price to the workman, for getting and filling, may be taken 

 at from 2d. to 5d. per cubic yard, for the various kinds of sands, gravels, 

 or clays ; and from 6d. to 2s. for harder materials, rock, &c., but, in addition, 

 various other matters are to be provided — barrows, planks, wagons, tempo- 

 rary railways, &c. — the present modern practice in moving large quantities 

 of earlh is vastly different to what it was in this country thirty years ago. 



or to what it still is on the continent, more particularly in the greater dis- 

 tance to which the material is carried ; these several distances between the 

 excavations and the points of depositing them, either into embank-ment or to 

 spoil, must be ascertained from the longitudinal section, and a careful exami- 

 nation on the ground— these distances are technically called the lead; for 

 distances under a quarter of a mile, the prices are higher, in proportion, 

 than for longer distances. Taking the average description of soils, and the 

 average distances. Is. per cubic yard may be taken as a covering first esti- 

 mate, upon the whole number of cubic yards of excavation or of embank- 

 ment, whichever may be the larger quantity shown upon the section. The 

 quantities of earthwork in a railway, on an average per mile throughout the 

 whole distance, might be taken as a characteristic of its cost, so far as mere 

 construction went, independent of carrying establishments, stations, and 

 land, over which items the engineers seldom had control. Mr. Vignoles 

 said it would be very interesting to have an abstract of the quantities and 

 cost of the earthwork, distances carried, &c., on all the railways, and indeed, 

 of all the other items of the works, as actually executed ; they would be- 

 come valuable precedents for future estimates, particularly if accompanied 

 by explanations of the circumstances under which the operations were car- 

 ried on. The great haste with which many of the railways were executed, 

 while the late powerful excitement lasted, had added greatly to the cost, by 

 raising the price of labour. Mr. Vignoles stated that he had already given 

 some such abstracts of the railways that had been executed by him, or under 

 his directions, and he was prepared to give more, and he hoped that other 

 engineers would follow his example, as it could not but be very satisfactory 

 to the proprietors of the different concerns, as well as a justification to the 

 engineers themselves, and to the directors, that they could go into the mi- 

 nutest detail of expenditure. The Professor then gave abstracts, in round 

 numbers, of the quantities of earthwork on many of the principal lines of 

 railway, as well as could be ascertained from the sections. He mentioned 

 the North Union Railway, twenty-one miles long, with 125,000 cubic yards 

 of earthwork per mile, at an average cost of lOjd. per yard, including all 

 extras and contingencies. The Midland Counties, 57| miles, with 100,000 

 cubic yards of earth per mile, at an average cost of 13d. per yard, including 

 slips and all charges, the soils nearly the same in each, and the average lead 

 nearly alike— viz., one mile— attributing the difference to the great haste and 

 great demand for labour in the latter. The mean of these would be now a 

 fair estimate. 



Having estimated for the cost of obtaining the artificial bed of the rail- 

 way, the next item would be the Bridging and 3/asonry— that is, to restore 

 the previously existing communications of roads, canals, or other railways, 

 the passage of rivers, watercourses, &c., &c., by viaducts, aqueducts, ordinary 

 bridges, culverts, drains, Stc, and often by heavy retaining and breast walls. 

 Under this head came the bridges of brick, timber, or iron ;— in very marshy 

 countries, where the foundations are likely to be bad, and the drainings 

 liable to be affected, timber may be resorted to, and used in the shape of 

 piling, with cross beams to sustain the rails across the openings, avoiding 

 thus the cost of arches, abutments, and wing walls. The ascertainment of 

 the several superficial or cubic quantities in each of these different construc- 

 tions, is a matter of simple mensuration from the working drawings. The 

 attachment of prices to these, in all their various details, with sufficient 

 accuracy, depends on the mature judgment and experience of the engi. 

 neer; and it is by a long course of careful study and observation that the 

 young student, in his employer's office, and on his works, can alone hope to 

 acquire this knowledge. It was but too common, in making estimates, to 

 fall short in this item, particularly in the number of occupation bridges, 

 which, owing to the complicated holdings, improvements, &c., had to be 

 provided for to a vexatious extent, or bought off. The masonry is generally 

 in proportion to the earthw ork, and in many cases has happened to be of 

 nearly the same amount of cost. The average number of bridges on a main 

 line of railway might be taken at five for two miles. Diversions and em- 

 banked approaches of roads, gravelling or metalling the new surfaces, and 

 the contingent operations, 'should be separately calculated. They are in- 

 cluded under the head of fencing,; of earthwork, or of bridging, or kept as a 

 distinct item, according to the practice of the engineer, but they form a 

 large sum, varying from lOOl. to 500/. per mile, according to circumstances, 

 and, in preliminary estimates, are too often omitted, or are put into that 

 refuge for all deficient items — contingencies. 



The item of Upper-Works in general, or permanent way, had been gone into 

 so fully in the recent lectures, that it was not necessary here to do more than 

 mention it, as forming a leading point in considering estimates. It is usua| 

 to add 10 per cent, upon all the items of the estimate, properly belonging to 

 the engineer. Besides these were the preliminary expenses of surveys and 

 Act of Parliament. The management, including cost of conveying, &c.. 

 and all salaries and expenses of direction, office, engineers, soliiitors, &c„ Jitc. 

 Then came the expenditure on the stations, engines, carriages, repairing and 

 building shops, fittings, and .all the carrying establishment necessary for 

 passengers, also for goods and for warehouses, wharfs, and other accommo- 

 dation. It was in them the heavy extra expenditure of railway capital 



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