A HERCULEAN TASK.

Hawera Star, Volume XLV, 4 August 1925, Page 10

A HERCULEAN TASK.

WATERLOO BRIDGE SPAN. NOTABLE ENGINEERING FEAT. Tne herculean task of ‘placing- the 509 tons double span of London's tempo i ary Waterloo Bridge m position ,eady for lowering on tne lour steel caissons which will eventually support it was successfully carried out on June t 6. operations were commenced at da vVoroak, and a few minutes arter noon the breaking of a Union Jack from a mast winch towered above the giant structure announced to the crowds which had gatnered on the Emoankment to watch the proceedings that the labours of the day were over. The span reaches across the space represented by the second and third arches of the old bridge, iin length som e 280 ft. The method of moving the structure from the old Waterloo Bridge, on which it was erected, to the new girder bridge, although unusual, was certainly justified • by the result, says the Daily Temgraph, for from start to finish the work went on without a hitch. So accurate were the e n gi nee r s ’ calculations that the structure did not deviate by a hair’s breadth, and therein lay the success of the task, for the slightest miscalculation would have thrown .the whole operation out of gear, and' adjustments, while entailing considerable delay, might also have introduced an element of danger. To move the framework across the 90it. of space between the old and th e new bridges it was necessary to lay two railway tracks, one at each end of the span, on steel girders. The span was then mounted on steel trucks with small bogey wheels to run on the rails. These preliminaries were completed on the previous night, and throughout the hours of darkness the staff and workmen stood by waiting for the dawn. At 4.30 a.m. the signal to begin was given and two steel hawsers were connected from the framework to hand winches at either end. Each winch was manned by four men. Slowly the handles turned, the vope became taut, and the massive structure moved forward a fraction of an inch. In the first minute an advance of two in dies was made, and afterwards, when it was ascertained tfiat everything was working out aceoiding to plan, there was an acceleration of speed up to six inches a minute. Each section of six inches was marked off attire side of the railroad girder, and signalmen with red and white flags motioned to the men at the winches when to begin and tease from winding. Between each forward step the progress was checked by the engineers, and so exact were the calculations that they were able to say that the structure had expanded on the morning heat by live-eighths of an inch. Soon the framework was clear of the old bridge towering above the river on its iron road, and by 9.3!) a.m. half the journey had been completed.

A brief halt was made for refreshments and then the winches were set going again, and the span moved on its wav by six-inch steps. Before the work began it was estimated that the span would be in position by noon; and aeu tally operations were completed a few minutes after that hour. A mighty cheer went up 'from the workmen as the last turn was given to the winches and the giant framework came to rest in the position from which ,it was to he lowered oil to its bed. The lowering of the span on to the "ylindricai caissons was carried out on the following two days. As on the first day it needed twenty repetitions of tlie sam e compound manoevure in order to ’ower the span bv 7jin. at a time.