Assessing air quality for the Ōtaki to North of Levin corridor

Ōtaki to North of Levin (Ō2NL): Te Pae o Tararua highway is one of four major roading projects to improve transport safety and connectivity across the Horowhenua District and the wider Wellington region. The highway is the final section of the road corridor upgrade, following construction of the Transmission Gully motorway, Mackays to Peka Peka, and Peka Peka to Ōtaki.  

Ō2NL is a 24-km four-lane highway and shared use designed to improve safety, support economic growth, provide greater route resilience, and enable better walking and cycling access for surrounding communities. The project is being delivered for NZ Transport Agency Waka Kotahi, Muaūpoko Tribal Authority, local hapū of Ngāti Raukawa te au ki te Tonga, and Horowhenua District Council. This section of highway needed a safety upgrade, with 72 deaths or serious injuries recorded between 2016 – 2021.

As part of the notice of requirement, Pattle Delamore Partners (PDP) was engaged in 2021 to undertake an air quality assessment of the construction and operational effects of the project.

We identified approximately 400 residential properties within 200 m of the proposed designation, and carried out a qualitative assessment to determine the potential for these properties to be affected by construction dust. 

Around 200 of these properties were within 50 m of the proposed designation boundary, and 70 were within 50 m of the anticipated construction footprint.  This meant unmitigated dust posed a potential risk of nuisance effects for nearby residents, and so we worked with the project team to develop mitigation measures to address this construction effect.

We also ran an air quality monitoring programme to establish current air quality levels in the Ō2NL designated area close to Levin, and carried out air dispersion modelling to determine the project’s future operational effects.  This modelling concluded that the project would improve air quality in the surrounding area, mainly driven by improvements to traffic flow on the new road.

PDP also supported NZTA through the consenting process by presenting at community engagement meetings.

The resource consent application was lodged in November 2022, and consent was granted in December 2024.  Construction began in October 2025, with the opening targeted for late 2029.