were
Although several methods considered for handling and transport- ing the beams, each some 53 tons in weight and over 106 feet long, the contractor finally decided to use the timber trestleway across the river initially provided for supporting the piling frames. The trestleway was substantially braced and strengthened with heavy timber and fitted with two 12" x 12" timber runners. Two 50 ton capacity bottle-jacks were placed at each end of the beam and, after raising, the beam was then lowered steel skid carrying plates fabricated by the contractor. The plates incorporated inverted channel units designed to fit over the 12" wide timber runners.
on
The trestleway across the river was extended into both casting bays on each embankment and the beams, supported at each end on the carrying plates, were smoothly winched, using two 10 ton diesel winches across the river into their respective spans.
Although loading contact
in excess of 30 tons the steel channel units slid easily on the greased timber
runners.
was
During handling care was taken to ensure that the maximum angle of tilt of the beam through the vertical axis did not exceed 6° and to fur- ther reduce the possibility of over- turning or flexing during transporta- tion the steel skid plates were pro- vided with brace attachments and wedges as illustrated.
As the top of the abutments and piers were stepped to cater for the deck cross fall these were levelled with timber to the same height as the trestleway. This enabled the contrac- tor to slide the beams sideways into position on the pier after which the weight of the beam was transferred on to four 25-ton bottle-jacks and the timber removed. The beams were then lowered on to the seating pads by the jacks.
Each end of the beams rested on "Freyssi Pads" formed of synthetic rubber between stainless steel plates
Mild steel reinforcement of deck footpath
Sliding a main beam into position on the bridge
and manufactured by the Freyssinet Co. Each pad measured 10" x 25" and consisted of two layers of rubber 10 m.m. thick set between three 1 m.m. stainless steel plates. The "Fressi Pads" were set on to high strength grout seatings raised 14" cast on to the abutment and pier top levels.
Road Deck
An 8" cast-in-situ road deck in 1:6 mix reinforced concrete was laid in the conventional manner and timber shuttering used for the deck soffit be- tween the beams. The contractor was able to lay the slab for each span in one operation. Although the slab was finished with a crossfall of 1:48 the thickness was uniform as the main beams were positioned in stepped levels across the piers to accommodate this cross-fall.
Expansion joints 2" in width were provided in the slab over the centre of each pier and 1" in width at the abutments. The joints were filled with bitumen filler carried in 22 gauge corrugated copper sheeting and the joint covered with a 1⁄2" mild
steel plate, 6" wide, set in bitumen. A I" gap filled with 'Pliastic' was form- ed throughout the complete length of the bridge between the carriageway and the water main service duct.
The deck carriageway was paved with machine laid asphaltic concrete 2" thick using a 4" max. size aggre- gate. Before surfacing the concrete was treated with an application of 'Colpave' bituminous emulsion at the rate of 0.2 gallons per square yard.
Handrailing
Polished anodised handrailing manufactured by the Nikkei Alumin- ium Co. of Japan has been provided in 6063 marine corrosion resistant aluminium. The handrail 3'-6" high and designed to withstand a hori- zontal force of 110 lb. per foot run at handrail level and was delivered and erected in prefabricated panels 8'-0" long. Aluminium was chosen for its corrosion resistant property. negligible maintenance cost, ease in erection and because it enhanced the aesthetic appearance of the bridge.
Approach Embankment
The approach embankments were built up in compacted layers of selected fill material to the designed profiles and provided with a 13" lay- er of crushed rock, a 3" compacted thickness of bituminous macadam base course and a 11⁄2” thick ma- chine laid wearing surface of hot rolled asphalt.
Supervision
The project was carried out under the supervision of the Development Division of the Public Works De- partment under the direction of Mr. J. J. Robson, M.I.C.E., A.M.I. Struct. E. Director of Engineering Develop- ment and Mr. J. Alexander, B.Sc.. A.M.I.C.E., Government Civil En- gineer.
Contractor
The contractors for the project were Messrs. Fung Kau Kee Salvage and Engineering Co. of 96-98 Tak Chong Street, Kowloon,
Far East Architect & Builder February, 1967
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