A Treatise On The Principles And Practice Of Dock Engineering

GOST 0F MAINTENANCE. 305 From which the cost of small metal gates in Germany may be considered as about 19s. per square foot—a figure very much lower than that quoted from Mr. Hunter’s report, but some allowance must be made for the locale of the statistics, as well as for the difference in size of the gates. TABLE XXIV. Cost of Construction and of Erection of One Pair of Gates for a Lock, 65 feet in width, with 40 feet of water over sill, exclusive of Operating Machinery and of Chains. Gkbenheart Gates. Timber......................£4,642 Iron and steel work,. . . 1,604 Labour.......................1,640 Erection.......................603 Total,. . . . £8,489 i.e., 49s. 9d. per square foot of gate, or 65s. 3d. ,, waterway. Steel Gates. Steel and iron work, . . £4,523 Pumps and valves, 183 Sheaves, &e., 85 Greenheart posts and silis, 425 Pitch-pine fenders, 200 Ballast, . . . . 206 Erection, . . . . 138 Total, . . £5,760 i.e., 33s. 9d. per square foot of gate, or 44s. 3d. ,, waterway. Area of waterway = width of lock (65 feet) x greatest depth of water on sill (40 feet). Mr. Nelemans states that, for a look 40 feet to 60 feet in width, the cost of creosoted pine gates may be taken at one-half of that of iron gates, and from two-thirds to three-fourths of that of oak gates.* He also gives it as his experience that, for looks ranging from 45 to 65 feet in width, iron gates, with double plating, cost an average of 20 per cent, in excess of oak gates, and, for looks of about 40 feet in width, gates with an iron frame and creosoted planking cost an average of 15 per cent, in excess of oak gates. These conclusions are based exclusively on statistics obtained from the more important maritime canals of the Netherlands. 4. Cost of Maintenance.—Reliable and extensive data for general application on this point are not forthcoming. The writer’s experience is that, in regard to greenheart gates, the cost of maintenance is practically nil. Gates of oak and pine are stated by Messrs. Brandt and Hotopp to require an annual upkeep expenditure of J to 1 per cent, of their prime cost. Some iron and steel gates are recorded as costing as much as 1 to Il per cent. Mr. Nelemans places the several materials in the following order as regards maintenance, commencing with the costliest : —Creosoted pine, iron, oak. He states, in this connection, that “the maintenance expenses of wooden lock gates exceed those of iron gates by 50 per cent., Nelemans on “ Iron and Wooden Lock Gates,” Min. Proc. Ninth Int. Nav. Cong., Düsseldorf, 1902. 20