A Treatise On The Principles And Practice Of Dock Engineering

RATIO 0F QUAY SPACE TO WATER AREA. 23 into the timber pond. The river frontage is also available for timber storage, as well as for a cattle wharf, if required, with a lairage at the rear. There are four surplus plots of land, triangular in shape, between the branches. These can be utilised as sites, partly for administrative buildings and offices, and partly for warehouses and goods dépôts, timber yards, and the like commercial adjuncts of a dock system. The land immediately adjoining the entrance locks will be advantageously occupied by the dock- masters office and residence, and by dwellings for dockgatemen and other officials whose constant attendance upon the spot is desirable. A convenient site will also be found in the vicinity of the graving docks for a pumping station and, if hydraulic power is to be employed, for one or more accumula- tors, though possibly the requisite power may be as readily obtained from an external source, such as the mains of a private company or of a municipal body. The design is an ideal one in this respect, that it présupposes an entire freedom of action in regard to site and outlay which is rarely attainable. There is nothing, however, to prevent the carrying out of the scheme partially or in instalments, as may be found necessary. Ratio of Quay Space to Water Area.—The ratio of quay space to water area will depend upon the relationship between the carrying capacity and the length of vessels which occupy berths in the dock in question. The following is an approximate statement of the nett registered tonnage of vessels per lineal foot, averaged from a considerable number of cases. It must be emphasised, however, that there is much variation dependent on the design of the vessel, whether for cargo solely or for cargo and passengers combined :— Vessels between 200 and 300 feet long, 5 to 6 tons per lineal foot. » » 300 ,, 400 „ 6 to 7 „ „ „ » ., 400 ,, 500 „ 8to l0 „ „ „ » » 500 ,, 600 „ 10 to l2 „ ,,” ». » 600 ,, 700 „ 12 to l5 ,, „ ” Assuming a cubic equivalent of 40 feet to the ton, it is evident that the volume of space required for the reception of cargo will range between 200 cubic feet per lineal foot for small vessels and 600 cubic feet per lineal foot for large ships. This accommodation may be provided, either in open quay space or within covered sheds, in which latter case the available area will be doubled or trebled, if the shed have two or three storeys. But as goods will rarely be piled or stacked to a greater height than 10 feet, and as allowance must be made to the extent of 33 per cent, for alley ways and passages, it will probably be equitable to take an average of 5 feet in height over the whole surface. Accordingly, a superficies of from 40 to 120 feet per foot lineal will be required for the accommodation of cargo, but this is on the assumption that the whole is deposited upon the quay before the removal of any portion. On the other hand, no provision has been made for the simul- taneous reception of outward-bound merchandi.se. The whole problem, in