THE SINGAPORE ENGINEER - Institution of Engineers Singapore

CIVIL & STRUCTURAL ENGINEERING
CONSTRUCTION OF FOOTBRIDGES
To allow seamless pedestrian connectivity between the
two 10 m wide promenades on each bank of the waterway,
five footbridges were built to span over the waterway at
strategic locations.
The emphasis in the design of the bridges was on both aesthetics
and barrier-free functionality. The ramps for the footbridges
were constructed with a gentle slope of 1 in 20, and grab bars
have been provided for ease of mobility for the elderly and
physically challenged.
Two of the footbridges, located at the western and eastern
mouths of the waterway, have a ‘horse-shoe’ layout. They are,
respectively, the Jewel Bridge and the Sunrise Bridge.
The Kelong Bridge has a ‘stilts-like’ theme while the Wave Bridge
has a slightly curved bridge layout.
The Adventure Bridge is a ‘suspended’ footbridge located in the
middle of the Town Park.
These footbridges were designed with sufficient height clearance,
for passage of maintenance vehicles along the promenade and
watercraft along the waterway - which was a challenge for the
engineers, given the site constraints.
The Jewel Bridge
The Jewel Bridge, located at the western mouth of the waterway
is a 160 m long and 4.3 m wide horse-shoe shaped footbridge
that follows a 22.6 m radius. Intermediate spans, 22 m long,
overcross the waterway.
Located right on the bridge, at the mid-span, is an enlarged (8.6 m
wide) space, with a jewel-shaped dome lined with vertical greenery.
The design of the bridge was inspired by the concept of a
precious jewel sitting atop a ring.
The façade of the dome is made up of circular hollow sections
of steel and acts as a focal point that highlights the confluence of
My Waterway@Punggol and Punggol Reservoir.
The bridge is fitted out with LED lights. Visitors can enjoy
interesting views against the evening sky and admire the sunset.
At the same time, from afar, against the backdrop of the setting
sun, the dome resembles a ‘floating’ platform.
The curved bridge has an equally curved concrete beam that
produces considerable amounts of ‘twisting’ torsional stresses.
Careful and rigorous structural design was required to deal with
the ‘twisting’ stresses in the curved bridge beam. The resulting
decision was to provide resistance by adding considerable
amounts of steel link reinforcements to the bridge structures.
This engineering option was adopted over the less aesthetically
pleasing solution of increasing the size of bridge beam. These
‘twisting’ stresses experienced by the curved bridge reached their
maximum, at the transversely enlarged 8.6 m wide space at the
bridge midspan. A few 300 mm thick concrete diaphragms were
added transversely at the bridge midspan to brace and control the
deflections at this enlarged space. Besides catering for pedestrian
park users, the footbridge was designed also to cater for the
accidental lateral impact loads caused by maintenance vehicles that
utilise the footbridge for crossing the waterway.
Footbridges crossing the waterway.
32 THE SINGAPORE ENGINEER April 2012