Extending the life of a critical SH1 bridge 

The SH1 Ngutuweru Stream Bridge strengthening project formed part of NZTA’s Region 3 and 4 Bridge Strengthening Programme. 

With increasing volumes of High Productivity Motor Vehicles (HPMVs) using the state highway network, the bridge required strengthening to meet modern loading demands while maintaining service on one of New Zealand’s busiest transport corridors. 

Working alongside Beca, Contech delivered an integrated strengthening solution combining advanced materials, specialist installation techniques and rigorous quality assurance processes. 

Importantly, the works were completed while maintaining live traffic movements across the bridge. 

A multi-layered strengthening solution 

The strengthening strategy combined several complementary systems designed to improve both local performance and overall structural capacity. 

These included: 

• Carbon Fibre Reinforced Polymer (CFRP) strengthening 

• Titanium alloy reinforcement bars 

• Steel shear bracket installation 

• Concrete repairs 

• Epoxy crack injection. 

Together, these interventions extended the operational life of the structure while increasing its ability to accommodate future traffic demands. 

CFRP strengthening under tightly controlled conditions 

CFRP strips were installed to the bridge beams to increase shear capacity. 

Successful installation relied on rigorous surface preparation and strict environmental controls. Concrete substrates were prepared to defined tolerances, while temperature, moisture and dew point conditions were continuously monitored before installation commenced. 

Bond strength testing formed part of the quality assurance process, ensuring the strengthening system achieved the required performance criteria. 

Introducing titanium reinforcement technology to New Zealand 

One of the defining features of the project was the use of titanium alloy reinforcing bars. 

The application represented one of the first uses of titanium strengthening technology on a bridge project in New Zealand. 

Working collaboratively with Beca during the design phase, Contech helped develop the methodology as an alternative strengthening solution. The proposal was accepted by NZTA, delivering a durable system capable of enhancing structural performance while offering exceptional corrosion resistance. 

The process involved detailed scanning of the existing bridge beams, precision groove cutting and the installation of specially fabricated titanium bars bonded into the concrete substrate. 

Inspection and quality assurance 

Quality assurance formed a critical part of the project. 

Testing and inspection activities were embedded throughout construction to verify compliance with design requirements and ensure long-term performance. 

From substrate preparation through to completed strengthening systems, every stage was monitored to confirm workmanship and material performance. 

Delivering complex works under live traffic 

Maintaining traffic flow on SH1 presented one of the project’s greatest challenges. 

Construction activities were carefully staged to minimise disruption while ensuring strengthening systems could be installed under the required structural conditions. 

Close coordination between construction teams and specialist traffic management providers allowed the works to proceed safely and efficiently, maintaining both network performance and construction quality. 

Project outcome 

The SH1 Ngutuweru Stream Bridge strengthening project demonstrates Contech’s ability to deliver technically complex strengthening works within operational transport environments. 

By combining advanced composite systems, innovative titanium reinforcement technology and practical construction expertise, Contech helped increase the capacity and resilience of an important piece of New Zealand’s transport infrastructure. 

The successful implementation of titanium reinforcement also established a benchmark for future bridge strengthening projects across the country.