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passes under the Lorne road extension about half a mile below the railway by an iron girder bridge of 17 feet 6 inches span having a headway of 17 feet.

In the second of these instances, where I have substituted a 5-feet arched culvert for a bridge of 20 feet span, I cannot but think some error must have been made in the original schedules, as from a careful examination of the stream I consider the culvert will amply suffice to carry the water.

25. The nett result of all these alterations has been a saving of Rs. 33,987'48, as compared with the total of this item in Estimate No. 4. Details showing the manner in which this is arrived at are annexed.

PUBLIC RECORD OFFICE

Reference :-

C.O. 882

ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH—NOT TO.

4 PUBLIC RECORD OFFICE, LONDON

Steww 1 to 1

Had the ground been level trans- versely, the area would have been the sum of the areas of the portions coloured red and blue, or 1,068 50 square feet, but owing to the tinnsverse slope of the ground, the actual aren to be excavated is the sum of the areas of the portions coloured red and green, or 1,9-0-50 square feet, an increase of 85 353 per

cent.

It will thus be observed that had the material been earth, the area to be ex- cavated would be 3.58 times that re- quiting excavation if rock be met with.

Surface of

Ground

Area

1950-8. fast.

Scale, 20 feet to 1 inch.

FIGURE No. 2.

Earth Cutting base, 16 feet Slope, 1 to 1.

C.-Bridges.

R..

Amount of Estimate No. 4

246,141

50

Add increase due to increased dimensions of piers and the use of

cement instead of lime mortar therein

Add cost of increased quantity of timber allowed for

18,115 1,554

265,810

0

0

50

Deduct cost of bridges Nos. 2 and 5 dispensed with Deduct cost of ashlar dispensed with

-

35,093

level line

Deduct nett decrease in cost of ordinary masonry after allowing for increase in section of wing-walls, &c.

10,456 50

45,549 50

8,106 98

Amount of present Estimate

-

53,656 18

912,154

Arpa

830-50|| 3. Pat

好

I have been thus detailed upon this subject inasmuch as I desired to make the matter, which most seriously affects the principles on which any railway estimate is framed, and on which, I think, much misconception exists, specially clear.

23. B.-Tunnels. In this item a saving of Rs. 22,000 has been effected by substituting cutting for the tunnel formerly scheduled as beginning at 6 miles 45.79 chains. This alteration has enabled me to dispense with a large amount of side cutting formerly scheduled as required to form an adjacent embankment. The maximum depth of the cutting now necessary is only 61 feet.

24. C.-Bridges. Under this heading the principal alterations suggested in the work as compared with that originally provided for are the following:-The omission of all ashlar except for girder bed stones where I deem it essential, and also the omission of all work in parapets and pilasters above formation-level; on the other hand, I have, as on this railway, provided for the abutments and piers of bridges on curves being 19 feet in length, instead of 18 feet as formerly, 10 feet 3 inches of this length being on the convex, and 8 feet 9 inches on the concave side of the curve, the object being to prevent the bed stones of the girders when spaced 10 feet apart centre to centre from being too near to the corners of the abutments. I have also provided for the use of masonry set in cement instead of in mortar for bridge piers, and have allowed for the top breadth of piers Nos. 2 and 3 of bridge No. 6 at 6 miles 10:40 chains, which are very high, being increased from 6 feet to 7 feet, the ends in all cases being, as before, vertical, while the sides have a batter of 1 in 24. I have also adopted in framing the present estimate for this item the sections for wing-walls built on this railway, which are stronger than those originally provided for, and have made a more liberal allowance for the longitudinal timbers on bridges.

A further alteration has been made by substituting culverts for bridges Nos. 2 and 5 formerly scheduled at 0 mile 61-64 chains and at 4 miles 15:45 chains.

In the first of these cases I have substituted a 16-feet arched culvert for a bridge of 30 feet span; this will, I am confident, afford ample waterway, inasmuch as this stream having in the meantime received the water from several ravines and water-courses,

ง

13585.1/87.

26. Before leaving this part of my report I desire to state very emphatically that I am not prepared to recommend the adoption of masonry for bridges inferior in the slightest degree to that executed upon the Nánu-oya railway, the specification for which is not, in my opinion, more stringent in any important particular than that adopted by the Public Works Department for first-class masonry; and it is needless to remark that if good and substantial masonry be required for roads, it is a fortiori required for a railway, where the structures are necessarily often much larger, and are subject to the direct strains and vibrations imposed by the passage of locomotives each weighing more than 20 laden bullock carts, and travelling at three or four times their velocity.

27. As regards the necessity for good masonry in piers, the case is, if possible, even stronger; and I would quote the case of the Pérádeniya bridge upon the Main Line, the only viaduct having masonry piers between Colombo and Kandy which is at all comparable in height and magnitude with the viaducts upon this and the Haputale railway. The Pérádeniya bridge is one of two 100-feet and two 60-feet spans, the height of the piers above low-water level is 41 feet, their length is 32 feet 3 inches, and their breadth at the top 9 feet 6 inches, giving a top area of 306,875 feet; they have a batter of 1 in 24, being the same as that adopted on this railway, where the viaduct piers of ordinary masonry for 80 feet spans, in some cases nearly 60 feet high above the bed of the stream, are 19 feet long at the top by 7 feet wide, thus having a top area of 133 feet.

The piers of the Lochiel viaduct, where the roadway is carried between instead of on the top of the girders, have a special length of 22 feet by a breadth of 7 feet at the top, thus giving a top area of 154 feet.

The piers of the Pérádeniya bridge are admittedly of much inferior masonry than that adopted on the Nanu-oya railway; they are not built for a double line of rails, for the present roadway being in their centre there is no room on them on either side for the additional line, and the only apparent reason for their large dimensions is therefore to obtain stability.

Upon comparison of the top areas of these piers with those 19 feet by 7 feet in area generally adopted upon the Nanu-oya railway, it will be, evident, if the cost of the masonry per cubic yard in the piers of the Pérádeniya bridge was only half that of the masonry in piers on this line, which is very unlikely, a very large saving has been effected by the substantial masonry built on this railway. In fact, in order that the

• Compare articles 59, 61, 62, 65, and 64 of Náau-oya railway specification with articles 18, 19, 20, 21, 22, 23, and 24 of "General Specification for Works-Boada," given at page 61 of Code of Departmental Regulations for Public Works Department, 1879.

i 28923.

D