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PUBLIC RECORD OFFICE
Reference:
TEC.O. 882
4PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT-TO
I may mention that the average annual rainfall For comparison with the above returns, at Nawalapitiya and Dimbula for the last 13 years has been 14166 inches and 111:32 inches respectively, and the maximum fall in any 24 hours recorded during the same period was at Nawalapitiya, 12.65 inches on September 10th, 1872, while at Dimbula, the maximum fall in any 24 hours was 960 inches registered on 9th May, 1883.
It is worthy of record, as illustrating the rainfall of Dimbula, that during the months of July, August, September and October, 1882, 137-58 inches of rain, falling on 102 days, were registered at Cameron's Land near the 23rd mile on the Nanu-oya railway, the greatest full in any one day during that period being 6-20 inches on the 30th July.*
I also annex a table giving the rainfall as recorded by the Officers of the Public Works Department at Padupola, about 4 miles to the west of a point on the Nánu-oya railway about 10 miles distant from Nawalapitiya, which may be taken, there being no intervening range of hills sufficiently high to intercept the rain clouds, as fairly repre- senting, though perhaps slightly in excess, the rainfall of that part of Ambagamuwa traversed by the Nánu-oya railway between the 8th and 15th miles from Nawalapitiya :—
1884.
No. of days
on which rain fell.
Means for 13 Years.
Inches.
Inches.
Days.
.13
2
2:57
5
January
·07
2
3.94
4
February
46
12
8.79
8
March
*43
9
11 48
14
April
7.91
30
17.70
13
May
34.25
25
38.39
24
June
July
28.73
31
33.34
24
August
37.31
28
30.57
24
September
25.14
27
26.60
19
42.95
27
30.29
22
October
-
November
12.80
13
15.83
17
14.65
18
8.91
10
December
204-83
224
228.41
184
204.83
Average daily fall 866 Average daily fall counting only those days on
and which rain was registered, viz., 224 Greatest fall registered in any 24 hours
and 23841}
Inches.
-56
365
204-85
228-41 184
191
-
6.89
Oct. 14-15, 1884.
Inches.
⚫62
-
1.24
18.80
Sept. 8-9, 1872.
From these returns it will be evident that the works on the Nánu-oya railway have to sustain the effects of an annual and diurnal rainfall, each more than twice as great as that which the works on an extension of the line to Haputalé will probably experience.
11. Bearing this milder climate as regards rainfall in mind, the first and most important modification I beg to suggest is a reduction in the depth of ballast. This will be referred to in detail further on under the heading of Permanent Way, and is merely mentioned here as on it and the consequent decrease in the bottom breadth of the ballast depend nearly every possible reduction in the work comprised in the construction of the railway proper, excluding stations.
12. 1 will now proceed to refer to the modifications I propose in detail, giving, as far as possible, the saving estimated as being effected by each such modification,
The prices at which the present estimate for every description of work is calculated are, where applicable, those set down by Messrs. Nowell and Co. for corresponding works on this railway.
See para. 86 of my letter to the Hon, the Colonial Secretary, No. 24 of 31st January, 1883.
SCHEDULE No. 1.
Works which, under a Contract similar in form to that for the Nánu-oya railway, would be executed by the Contractor.
13. A.-Earthwork.-I propose to reduce the formation widths of cuttings in rock and earth from 16 feet and 20 feet to 15 feet and 18 feet respectively, and also, in cases where there would otherwise be spoil, to reduce the formation width of cuttings in earth to 15 feet also, the sides of the ballast being in such cases as well as in rock cuttings packed up to a slope of to 1.
Experience upon this railway has shown that, owing to the general short lengths of the cuttings, there need be no apprehension of scour taking place in the small ditches at the edges of formation, but that even in earth cuttings on a gradient of 1 in 44 their tendency is, on the contrary, to silt up.
The formation breadth of embankments is reduced from 18 to 17 feet, and in cases where side cutting is required to 16 feet; and upon these reduced breadths the earth. work quantities have been calculated.
The effect of these reductions in formation width has been to reduce the estimate for earthwork by Rs. 107,861 10 as compared with the price set down for this item in Estimate No. 4.
Recent railway practice affords several instances of the adoption of formation widths somewhat similar to those now recommended. On Prussian railways having a gauge of 4 feet 8 inches the formation width for a single line is 15 feet 6 inches. On French railways the minimum formation width in cuttings for a single line to the edge of the ditch is 11 feet 7 inches. On English railways the average formation width for a single line is 18 feet. In Victoria* the average breadth of formation for a single line, the gauge being 5 feet 3 inches, is 16 feet 6 inches. Upon the North-Eastern railway in that Colony, beyond the first 60 miles this width is 17 feet in banks and 18 feet 6 inches in cuttings. On the Canadian Pacific railway the formation width of embankments is 14 feet. On the St. Gothard railway‡ the formation width of banks is 17 feet 2 inches, and that of cuttings, excluding side drains, 17 feet 8 inches; but on the mountain section these widths are increased by 8 inches. On the West Shore railways in the United States, which is not a "cheap" American railway, but one constructed in a settled country to serve a large traffic-
The formation width of banks is
Do. Do.
earth cuttings rock cuttings
•
15 feet.
20 * 17
"
14. With reference to the question raised in the 4th paragraph of your letter No. 25 of 3rd March last, I have the honour to report that, having carefully walked over about one-quarter of the Haputalé extension, I do not feel that it would be safe for me, for the following reasons, to make any alteration in the anticipated proportions of rock and earth, nor to encourage the Government to count upon any considerable saving, even if the amount of rock were very much less than that scheduled, or even if no rock at all were met with.
15. An examination of the strata disclosed by the cuttings on this railway, which can now be made by any observant traveller, will show their excessive irregularity.
16. In some cases the cuttings will be found to be of earth, except perhaps at one or two points where huge boulders, of which no indications appeared on the surface, but the tops of which lie at only a few feet below it, and which form a very considerable portion of the contents of the cutting, occur.
In other cases the whole of the cutting is through boulders and earth, without any regular stratification. While again, in other cases, a regular stratum of rock or of boulders lying close together, perhaps only one or two feet thick, is met with extending right across the cutting, below which earth again occurs. I have every reason to think that the cuttings upon the Haputalé railway will be through material generally similar to that met with on this line.
1 13123.
• Report of Captain Tyler, R.E., to Board of Trade for 1875. Proceedings, Inst. O.E., vol. lxxi, page 383.
Proceedings Inst. C.E., vol. lxxiii., page 898. Proceedings, Inst. C.E., vol. lxxvil, pago 248.
B
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