- Publication no: ABC-DES045-11
- Published: 31 October 2011
The NIMTR Bridge is a road bridge carrying four lanes of state highway traffic over the North Island Main Trunk (NIMT) railway and the proposed Onion Road Extension. It is the longest bridge in the NZ$210 million Te Rapa Section of the Waikato Expressway project, currently under construction. The Te Rapa Alliance, set up by New Zealand Transport Agency (NZTA), Opus International Consultants and Fulton Hogan, developed an optimized alternate solution to the specimen design provided in the tender. The new bridge is a 142 metre 4-span structure, comprising of concrete-steel composite construction with foundations at a skew angle of 61 degrees. Innovative solutions were developed to challenging constraints including the extreme skew of the railway tracks, the alignment of the Te Rapa Section, railway clearance and impact provisions, asymmetrical lateral earth pressures, soft ground conditions and other Principal’s Requirements, such as abutment batter slopes. Other design considerations include durability provisions for the structural steelwork and constructability over the railway. In comparison to the reinforced concrete specimen design, the alternative final design was innovative and highly materials efficient utilising 800 tonnes of structural steel, providing significant savings in the materials and construction costs of the bridge.