The project forms part of the Far North District Council's HPMV bridge upgrade programme, aimed at improving the capacity of existing bridges to accommodate higher-productivity motor vehicles and support the long-term resilience of the regional transport network.
Extending the service life of existing infrastructure
Rather than replacing the existing structure, the H16 Broadwood Bridge is being strengthened through the installation of an external post-tensioning system.
The BBR VT CONA CMS solution introduces additional post-tensioning forces into the existing structure, increasing its structural capacity while making extensive use of the bridge's existing fabric. This approach can provide an efficient solution for upgrading ageing infrastructure while reducing the extent of structural intervention compared with more extensive replacement or reconstruction works.
For the H16 Broadwood Bridge, the strengthening works include the installation of external post-tensioning tendons together with dedicated anchorages and deviator assemblies integrated into the existing bridge structure.
Engineering and installation within an existing structure
Retrofit projects require a different approach from new construction, as every intervention must be carefully integrated with the existing geometry and reinforcement.
The works therefore included detailed reinforcement scanning and setting-out prior to precision drilling and installation of the anchorage assemblies. Once the external tendons were installed, the high-strength strands were stressed to introduce the required strengthening forces into the bridge.
The project also demonstrates the flexibility of the CONA CMS supply concept. Depending on project requirements and local capabilities, the system can be supplied in different configurations. For the H16 Broadwood Bridge, the CMS anchorage blisters were prepared locally by Contech, combining BBR system technology with local capabilities and expertise.
This flexible approach enables the BBR Network to adapt the implementation and supply of the system to different project and supply-chain requirements.
The project also required careful planning due to the constrained working environment beneath the existing bridge and the site's location in Northland. Contech's excellent contribution, together with close cooperation between BBR, Contech and United Civil Construction, supported the successful implementation of the strengthening works.
A flexible solution for structural strengthening
BBR VT CONA CMS is an IP-protected, strand-based structural strengthening system developed for external structural strengthening and retrofitting.
Its compact anchorage arrangement, multiple fixation options and use of proven 7-wire prestressing strand technology make the system particularly suited to applications where existing geometry, reinforcement and accessibility place significant constraints on strengthening works.
The system can provide a prestressing force of up to 223 kN per tendon and incorporates dual anti-corrosion barriers to support long-term durability. Its flexible configuration also allows the solution to be adapted to different installation and supply requirements.
Expanding BBR Care+ solutions in New Zealand
The H16 Broadwood Bridge represents an important reference for the application of BBR VT CONA CMS technology in bridge rehabilitation and strengthening.
As infrastructure owners increasingly look for ways to extend the service life and capacity of existing assets, strengthening and retrofit solutions can provide an alternative to complete replacement, preserving existing structures while adapting them to new operational requirements.
The project further strengthens the cooperation between BBR and Contech and demonstrates both the technical capabilities and the flexible implementation model of the BBR Network, combining specialised BBR technology with strong local expertise.
It also demonstrates the potential of BBR Care+ solutions for Maintenance, Repair & Retrofitting (MRR) applications across New Zealand and the wider region.
