Update to Road Engineering Manual: Forest Road Design for HPMVs

The NZFOA/NZFFA Transport and Logistics committee is pleased to announce the release of a new appendix to the New Zealand Forest Owners Road Engineering Manual, titled Forest Roads for High Productivity Motor Vehicles with Two Drive Axle Log Trucks.

Prepared by Paul van der Voort from Forest Management NZ Ltd, and supported by funding from the Forest Growers Levy Trust, this update provides essential guidance for designing forest roads to accommodate High Productivity Motor Vehicles (HPMVs).

HPMV trucks, which can carry up to 58 tonnes and extend to 23 metres in length, have become popular in the forestry sector. However, these vehicles require different road design considerations compared to older, smaller configurations. The original manual’s design specifications, based on trucks with a 44-tonne capacity and 20-metre length, are no longer sufficient for the heavier longer HPMVs.

This appendix offers practical solutions to address these challenges. It includes updated charts for curve widening, recommendations for road gradient, camber, and pavement materials, and emphasizes the importance of road surface compaction. It also discusses the increased stress on roads due to heavier axle loads, advising on pavement design and construction.

Additionally, the appendix acknowledges the critical role of driver skill in navigating forest roads, especially in difficult conditions, and provides recommendations for situations where HPMVs may not be suitable.This update is a valuable resource for forest road engineers and planners, ensuring roads are safe, efficient, and capable of handling modern truck configurations while adhering to environmental standards.