Gall Zeidler Consultants designed two mined sections of the tunnel to pass under the existing major roadways (Telok Blangah Road and Kampong Bahru Road) including the temporary and final support, waterproofing, structural and geotechnical instrumentation, and monitoring programs.
Design Services and Consulting for Micro Tunneling Support System:
The double-lane tunnel crosses under Telok Blangah Road between existing bridge piers under a maximum overburden of 8 feet (2.5 meters). It is equipped with an emergency shoulder and walkways. The final structure will be formed by a single-cell reinforced concrete box that will be erected within a temporary steel pipe box structure. The single-lane tunnel is equipped with an emergency shoulder and walkways. The tunnel crosses under Kampong Bahru Road in an easterly direction, passes under a three-cell concrete culvert with minimal clearance and continues along Keppel Road with a maximum ground cover of 26 feet (8 meters).
The temporary structure will comprise of steel pipes arranged in a box-like structure. These large diameter 2.7 feet (0.82 meters), heavy steel pipes will be used to pre-stabilize the ground surrounding the final tunnel. The steel pipes will be installed by micro tunneling methods around the final structure to provide initial ground support. The interlocking pipes will be filled with concrete.
The design allows for utilities and roadway traffic to be kept operational during tunnel construction.