Boroko Creek crosses the Sir Hubert Murray Highway between Erima and 8 Mile. The existing steel bridge accommodates two lanes. A new bridge with four lanes is required for the proposed Sir Hubert Murray Highway upgrade.
Madsen Giersing (MG) was appointed by Dekanai Construction to provide the detailed design and technical support services for the design of the new bridge.
The new bridge is a single span bridge, 26m long by 25.7m wide. There are 4 traffic lanes, two pedestrian footpaths on either side of the bridge and a 5m wide centre median strip to align with the highway geometry.
The available hydrological data show a substantial flow in the creek during a flood event. The existing creek bed at the bridge is approximately 10m wide and the bed level is approximately 2.5m below the existing bridge deck. The new bridge length is set to 26m to accommodate the flow during a flood event and the creek bed and sides are protected with Reno Mattress.
The bridge superstructure consists of 1500mm deep prestressed concrete super T-girders with open top flange. The insitu concrete deck is 150mm thick under the traffic lanes and concrete deck.
The geotechnical investigation of the bridge site shows the bedrock level is close to the ground level. The abutments are supported on bored piles embedded into the bedrock to achieve the required geotechnical capacity. The bridge is restrained at both ends for breaking and seismic forces whilst accommodating thermal expansion.
Papua New Guinea