Merit, Urban and Redevelopment Authority Southern Ridges Bridge International Design Competition 2004

Spanning over Henderson Road, the bridge twists and turns to connect to meaningful destinations such as existing exercise stations, park pavilions, hill top roads and dips down to existing steps and footpaths.  It is sinuous in elevation to climb gently for wheelchair users and meanders around trees and existing hill contours.  When it needs to be closer to the ground, it dips down to reduce the heights of tis vertical supports. And it cantilevers in mid-air where there are views to Pasir Panjang or near the trees, for people to experience the crossing as an unfolding sequence of vistas tempered with shadows and streaks of light. 

It is a bridge that changes its shape and direction to fit the site. At night, it is a lantern for road vehicles.  The timber slits part at certain key positions for bridge users to peak through and orientate themselves along different stages of their journey.  The bridge is also an elongated trellis for vines and climbers to grow, the longest hanging garden in the world experienced inside a single bridge crossing.  It will attract little birds, squirrels and insects.  In time to come, it will be at once, a vine, branch, hanging garden and dragon at Henderson.

The sinuous form of the bridge results in many out of plane forces and torsions, and the box truss type of construction is used to counter these forces effectively. The proposed structure is a series of box trusses with seven support positions.  Observation outposts are designed as cantilevers supported from the main bridge.  The longest span along the main bridge is 60m while the longest spanned cantilever is 25m.  The box truss is made up of SHS.  Skewed columns are designed as 20m high CHS.

Due to the manner in which the bridge curves on plan, torsional forces are induced naturally but effectively resisted by the boxed up section.  The overall stiffness of the section is large such that buckling of the in or out of plane will be prevented given that the critical sections are at the 60m clear span and 20m cantilever. The effective depth (2400mm) and width (4000mm) of the main bridge section is stiff enough to overcome issues of dynamics.  The roofing and deck systems will hold the main chords together to form an integrated bridge section.  Tuned mass dampers can be introduced to reduce any perceptible acceleration.

dragon bridge 1
dragon bridge 2