CIVIL ENGINEERING & PUBLIC WORKS
Dividing the two carriageways in the centre of the bridge is a 5 ft. void, so that in effect there are twin bridges side by side.
Of reinforced and prestressed con- crete construction, the bridge has three spans
a 20 ft. 2 in. approach span on either side and a 50 ft. centre span. Because of the very soft nature of the river bed, which pre- vented the erection of supports for formwork, it was necessary to precast the components of the centre span. The two approach spans were, how- ever, cast in situ,
Long Piles
The bridge is supported by two piers and two abutments. Each pier rests on 30 piles with a maximum load per pile of 38 tons. Each abut- ment is on 13 piles of 30 tons maximum loading each.
Piles had to be unusually long to provide an adequate footing in the soft mud of the river bed. Each 14 in. by 14 in. reinforced concrete pile is 120 ft. long, made up of three 40 ft. sections with 1⁄2 in. mild-steel end-plates welded together in situ.
For each pier, piles were driven at 6 ft. centres in two rows, the rows being 4 ft. apart. Each abutment rests on a single row of piles driven at 7 ft. centres.
The 50 ft. centre span of the bridge is made up of 40 prestressed and precast concrete beams, each 2ft. 11⁄2 in. high and 1ft. 8in. wide at the base. These were manufac- tured by Hume Industries (Far East) Ltd. and brought from their yard to the site at weekends by trailer.
On top of the precast beams were laid 6in, thick reinforced concrete slabs. These were cast in situ.
At each end of the precast beams. 34 in. expansion joints were provided. The ends of the beams rest on Andre rubber bridge bearing pads (instead of the more traditional type of steel rollers) which facilitate expansion
movements.
The two 20ft. approach spans are of T-beam and slab construction. The T-beams in this case were cast in situ.
The two carriageways of the bridge, each of which has a 6in. fall
River lining in the area of the new Geylang Bridge
Geylang Bridge under construction
for drainage, are surfaced with a 2in. layer of asphalt premix. Pro- vision is made under the footpaths/ cycle tracks at each side of the bridge for services which are laid in the hollow space below the 5ft. 4in. by 1ft. by 5in. thick paving slabs. Services are thus easily accessible for maintenance.
Along the edges of the central
divider between the carriageways and also along the outer edges of the bridge, 2ft. 9in. high mild steel rail. ings are placed as protection for motorists and pedestrians.
The cost of the new bridge was approximately M$400,000.
The main contractors were Union Contractors Ltd. Piling was by Sum Cheong & Co. Ltd.
RAILING
Z FALL
-.R.C.NO. 4 (T. & N.5
•FALL
_3+0*;
25-4′′
24-0
FALL
Far East Architect & Builder August, 1965
RAILING
-1. R.C. NO. 4 x ...)
12T 5 PRECAST SLABS
4 FALL
2' FALL
wwwwwwwwww
21-4
24-0
MAILING
• FALL
CROSS SECTION OF DECKING
& THE BEAMS.
3-0
17-0
-ŒES" PRECAST SLABS
2'FALL
-12% 61, TIE BEAMS
4-9
73