SKILFUL BRIDGE FEAT.

New Zealand Herald, Volume LX, Issue 18564, 23 November 1923, Page 10

SKILFUL BRIDGE FEAT.

HANDLING HUGE TRUSSES.

SUCCESS AT MANGAKAHIA.

[BY; TELEGRAPH. —OWN CORRESPONDENT.] "'■ •''■■ : * •• ; .".■'•'WHANGARKI, Thursday. A noteworthy feat of engineering in bridge construction was effected yesterday in connection with the construction of the upper Mangakahia bridge on the I'akatai-Kaikohe Road. The main span trusses of 110 feet in length were fully assembled, and last night saw the downstream truss safely across in position. The upstream : truss had been placed in position a few days previously. ' The usual method of ; construction ' of such bridges is to ! build trusses of this size on a temporary staging which in itself, is a work of considerable magnitude, exposed to detraction by even ordinary floods. During the construction of the old bridge, near the site of the one now being erected, the staging was carried away and severe loss was sustained by the contractor. A similar disaster occurred during the construction of the big Mangakahia bridge at TitokL; farther down the' stream. : : •'■.:.', i-y v ; >

■~ In the present instance the contractors built each truss ashore and hauled them over suspended on ropos. The - weight of each truss was upwards of 20 tons, but the handling of this large weight did not constitute .the. main difficulty. It was necessary to keep the truss, which is some . 18ft. .in height, in an upright position. A light temporary trestle some 25ft. high, was built on the permanent pier to carry th<s two top supporting rapes which caught the truss about five feet below the top chord. The lower chord was supported on top of two lower ropes. The hauling engine was a. simple hand-power Trevella stump jack, operated by two men. "