Characteristics of log trucks on New Zealand roads

Authors: Campbell Harvey and Rien Visser
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2024, Issue N.Z.J.For. 69(1) 2024, pp Pages 11 - 16, May 2024
Publisher: New Zealand Institute of Forestry

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Abstract: Log truck characteristics in New Zealand have changed considerably in the last decade with the introduction of the High Productivity Motor Vehicle (HPMV) designation. HPMV combinations can be both heavier and longer than the previous 44 tonnes (t) standard log truck-trailer. While a ‘standard’ HPMV configuration (with a sub-designation the ‘50MAX’), is a 50t Gross Laden Weight (GLW) combination vehicle, trucks can be loaded in excess of 60t with the correct permits acquired and vehicle configuration. Operating higher GLW log trucks can improve both cartage cost-efficiency and reduce the total trips required to cart the same harvested volume. However, higher axle loading and increased length from HPMVs have an increased impact on road infrastructure and may require improved forest road design standards, including pavement thickness, road grade limits and minimum curve radii. This report uses both a large weighbridge data set (20,500 data points), as well as a Central North Island truck survey to provide an overview of current truck loading and configurations. It finds that 50t is the most common GLW which is aligned with the standard 50MAX category. However, 54t and 58t combinations (aligned with standard HPMV permit categories) make up almost 50% of the total trips. The overall average is 51.1t, but 10% of all loads are greater than 56t. Log truck and trailer tare weight average was 17.4t. From the survey, the most common log truck configuration (63.5%) is a 4-axle truck with a 5-axle trailer, but 33% of all log trucks still operate 4-axle trucks with 4-axle trailers.

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