Case Study: Tonkin + Taylor improves motorway design efficiency with Seequent’s Leapfrog Works

3D Modelling Plays Important Role in Design of New Zealand’s Pūhoi to Warkworth Motorway

Tonkin + Taylor, as part of the Design Joint Venture with Beca, faced the challenge of designing New Zealand’s 18km Puhoi to Warkworth motorway extension through steep hills, valleys, and soft alluvial sediments. The project involved major earthworks, seven bridges, and three viaducts, making a reliable ground model essential to reduce geotechnical risk. Seequent’s Leapfrog Works 3D geological modelling software was used to support the design.

Seequent enabled the team to build a dynamic 3D ground model from extensive investigation data, including 210 CPTs, 420 boreholes, 355 hand augers, and 220 test pits. The model improved collaboration, sped up section generation, and helped compare alignments and optimise cut-and-fill earthworks in Bentley OpenRoads, reducing time, effort, and waste while improving decision-making. Seequent’s solution saved the team from repeatedly recreating models and gave stakeholders a clearer understanding of site conditions.

Tonkin + Taylor

Stuart Cartwright

Senior Engineering Geologist