Project Engagement
Weir was engaged by Concrete Structures Limited (CSL) to undertake the hydraulic analysis to design a new bridge over the Kakanui River, in North Otago. The existing timber bridge, circa 130 years old, was to be replaced with a new 162m long timber bridge with eleven-spans (i.e., 10 x 750mm diameter piers).
CSL proposed an alternative concrete bridge design, with seven spans (i.e., 6 x 1200mm piers). This alternative design was accepted by Waimate District Council (WDC).
Hydraulic Modelling & Assessments
In delivering our services, our engineers worked alongside our modelling partners, Submergent, to develop a TUFLOW model to support hydraulic analysis and bridge scour assessments.
Key Contributions
Confirmation of the necessary 1.2m freeboard for the SLS2 (1/100 year ARI) flood, and 0.6m in the ULS flood (1/1000 year ARI with an allowance for the effects of climate change under the RCP8.5 scenario, with a climate horizon of 2130).
Allowances for pier scour depths for proposed piles (i.e., pier scour mitigated via pier foundation design, rather than implementing engineered scour mitigation solutions).
Riprap protection of the embankments and a riprap apron for managing potential scour at abutments.
Relevant parameters for structural analysis and design of bridge to accommodate the revised hydraulic conditions generated by the alternative bridge design.
