152. The northern approach road 1,200 feet long, founded on swampy ground, is constructed with a 9″ foundation course of granite bottoming, 4″ base course of 1½″ bituminous macadam and 1½″ carpet coat. The southern approach road 1,900 feet long on better ground is of 8″ vibrated concrete with 1½″ thick wearing coat. The concrete of 1:6 mix, ordinary Portland cement, 1½″ max. graded granite aggregate and water cement ratio of 0.45 gave average compression test results of 5,000 and 7,000 lbs. per sq. in. in 7 and 28 days respectively.
The bridge and approaches were completed towards the end of the year.
Reconstruction of the Ma Niu Shui Bridge
153. This bridge carries the Tai Po Road across a narrow ravine some 13 miles from Kowloon.
The original bridge was of reinforced concrete beam and slab construction 90 feet long of 3 spans, 25 feet, 40 feet and 25 feet with a width of 18 feet, concrete piers and abutments and with deck level 45 feet above a mountain stream. The existing structure which is being replaced is of special interest as it actually consists of two bridges, one on top of the other. During the withdrawal of the British Forces in December 1941 demolition charges were fired. The bridge dropped and the main beams, still attached to the abutments, swung downwards resting on the collapsed piers, the broken deck forming a shallow V 12 feet deep and 90 feet across. During their occupation of the Colony the Japanese constructed a light bridge of seven spans on the remains of the original. Their piers were of rubble founded on the old piers and broken decking and carrying rails as beams to support timber decking which in turn carried a tarmacadam running surface at the original level. This rather crazy looking structure is still in use, subject to a 9-ton weight restriction, pending the completion of the new work which commenced in February 1952.
Page 40