GREAT SEA LOCK.

New Zealand Herald, Volume LXVI, Issue 20367, 23 September 1929, Page 13

GREAT SEA LOCK.

LARGEST IN THE WORLD.

A TEN-YEARS' LABOUR.

APPROACH TO AMSTERDAM.

In the course of a few months there will be opened to traffic a largo now lock for ocean-going vessels entering and leaving the Ship Canal which forms the principal approach to the port of Amsterdam from Ymuiden on the North Sea. The lock is of outstanding size, and far exceeds any othor structure of the kind in existence at the present time. Compared with the Panama Canal locks, the chamber for the reception of shipping represents an increase in cubic capacity of over 100 per cent.

Tho dimensions of the new lock are 1312 ft. long by 164 ft. wide, with a depth of water over sill of 50ft. below mean sea level. Tho Panama Canal locks have a length of 1000 ft., a width of 110 ft. and a depth of 42ft. Tho locks on the Kaiser Wilhelm Canal from the North Sea to the Baltic, specially enlarged just beforo the war, are 1083 ft. long by 148 ft. wide by 45ft. deep. Tho Ymuiden sea lock is not only far in excess in size of any ship canal lock in tho world; it is also much in advance of any ship at present navigating the high seas. The largest vessel at tho present time is the Majestic, which has a length of 956 ft. over all, a beam of 100 ft. and a loaded draught of 38ft. There is a vessel building for the White Star Line of somewhat greater tonnage, but the dimeo sions of tho Majestic will not be greatly exceeded in tho new liner.

Early Miscalculations.

Obviously it indicates great confidence on the part of the port authorities at Amsterdam in future developments at the port to construct a lock of such a size and to incur an outlay thereon which is represented in round figures by a million and a-half sterling. The undertaking, indeed, was embarked upon fully ten years ago, when the building of large ships was more definitely in abeyance than at present, and the enterprise and forethought so displayed, if justified by the future, will redound greatly to the credit of the Dutch people and their technical advisers The magnitude and duration of the work warrant some notice of its inception and execution. The port of Amsterdam, which up to the beginning of tho nineteenth century could only be reached from tho open sea through the shallow channels of the Zuider Zee, is now in direct communication with tho North Sea by means of a canal 15£ miles in length, which was opened in 1876, and which affords a passage for ships with draughts up to about 32ft. A pair of entrance locks were originally provided, the larger of which was 394 ft. long by 60ft. wide, with a depth of over sills. It was not long, however, before an entrance of these modest dimensions proved quite inadequate for requirements. Some Striking Figures.

A new and larger lock had to be provided, and such a lock with a length of 737 ft., a width of 81ft. and a depth of 33ft. was constructed to the north of the old locks and brought into use in 1896. Not many years afterwards it was realised yet again that the developments in ship construction had overtaken the available accommodation* Another lock of larger size became imperative, and a commission appointed by the Dutch Government in 1909 to examine the question decided on a lock with dimensions 1148 ft. by 141 ft. by 44Jft. Before effect could be given to the commission's recommendation, the war intervened, and when constructional operations were actually begun in 1919, the dimensions adopted were those already stated at the beginning of this article. In view of the earlier miscalculations it was felt that this time a sufficiently large margin should bo availablo to cover any possible developments for a number of years to come. Work of Ten Tears' Duration.

In a work which has required ten years to carry through, and which has cost a million and a-half, quantities of material handled and dealt with must be on a considerable scale. Tho excavation of the site totalled 26 million cubic yards. There are 15,500 bearing piles in the foundation and the walls and sills contain nearly eight million cubic feet of concrete reinforced by 19,000 tons of steel bars. There are throe large caissons for closing the entrances of the lock and each of them weighs 1200 tons. These few figures will give some idea of the magnitude of the task which has for a decade engaged tho attention of Dutch engineers, but they hardly convey an adequate impression of tho numerous difficulties and problems in design and construction which had to bo thought out and solved in dealing with a structure on a scale so far in advance of anything previously attempted.