This project concerns an approximately 10km section of the motorway, delivered via a large-scale alliance between NZ Transport Agency Waka Kotahi, Christchurch City Council, and Fulton Hogan at a cost of $290m.
Before joining Awa Environmental as Principal Landscape Architect, Mike Pentecost worked as a Senior Landscape Architect on the project – from alliance bid in 2015 to project practical completion in 2021.
Mike played a lead role in in developing the planting strategy and design of a connected ecological corridor along the new motorway and contributed to designs for an innovative shared user path, important structures – such as illuminated bridges and cycle underpasses – and nature-based stormwater solutions.
The overall project received top honours at the Civil Contractors New Zealand – Canterbury Westland Awards 2021, winning both innovation and environment awards for its design and sustainable management practices.
Challenges
Building major transport infrastructure in challenging geotechnical conditions, including marsh soil, and in a low-lying area that had elevated flood risk.
Delivering a cohesive landscape outcome across a large, linear infrastructure corridor.
Integrating transport infrastructure with a strong ecological and visual identity.
Coordinating design within a complex, multi-party alliance environment.
Providing safe, accessible, and high-quality outcomes for multiple user groups, including recreational pedestrians and cyclists, and daily cycle commuters.
Providing an ecologically sound outcome on time and within budget.
Solutions
Mike collaborated closely with all members of the alliance to ensure on time and in budget delivery of his contributions, and design consistency from concept to construction.
He helped design a connected ecological corridor along the new section of motorway that supported native species and linked other significant sites, such as Deans Bush and Ōtukaikino.
Central to this was a planting strategy based on pre-existing natural ecosystems – a successional Canterbury plains forest – which re-introduced plant communities and habitat once lost to the area and earned the corridor the nickname “Tōtara Highway”.
He integrated this with landscape and structural elements, such as bridges and cycle underpasses, to help create a unified corridor experience aligned with the ecological theme.
Mike also contributed to the design of a shared user path and incorporated multi-modal transport options to ensure the corridor provides more than just road transport.
The path utilised innovative design features, such as inclined subway walls to give the sense of more space, and safe areas for pedestrians to move to when cyclists pass.
Mike helped enable holistic stormwater management by championing nature-based solutions in his designs, including extensive natural planted areas to reduce road flooding risk, improve surface runoff quality, and trap sediments within natural planted swales.
This involved proving to senior project leaders that natural planted areas were more cost effective over the long-term than traditional mown turf grass.
Benefits
New ecological connections and creation of habitat.
Cost-effective flood resilience through nature-based solutions.
Improved transport efficiency while providing ecologically sound outcomes.
High-quality walking and cycling infrastructure along the corridor.
A distinctive landscape identity for the route established.
Effective and efficient project delivery within a complex, multi-party alliance.
Project Highlight
Ecological corridor, shared pathway, and holistic stormwater solutions boost amenity and value of new motorway (2015 - 2021)
