Converting woody debris into roading material is proving to be a winner for the environment, both in minimising gravel use and mitigating build-up.

Managing woody debris left after harvesting is a common challenge in forestry. Once it is cleared from the cutover and safely stacked, the key issue remains—how to handle the material. Transporting it out of the forest is costly, while leaving it piled on landings can pose environmental risks during severe weather events. With funding from Forest Grower’s Research (FGR), Pan Pac and FGR have been trialling a promising solution – using it as roading material.

On Friday 21 February, around 50 forest industry representatives from across the North Island joined Pan Pac and FGR in Mohaka Forest to get a first-hand look at the shred wood road trial in action.

Compared to metal roads, shredded wood roads offer the environmental advantage of repurposing waste wood while reducing traditional roading material transport distances, thereby lowering the carbon footprint.

Hamish Scown, Pan Pac Forests Operations Technical Coordinator, who has played a key role in running the trial, says the trial has produced some promising results so far, and has helped to identify the limitations and maintenance requirements of shred wood roads.

“The results so far indicate that shred wood roads could be a viable alternative to metal roads, where the grade is not too steep in wet conditions. In any case, in dry conditions loaded stems units and 50t conventional trucks have been leaving the site uphill loaded at 11.5% with no run up. It is likely that a light spread of traction metal will help in wet conditions as per normal wet weather roading operations and that is something we will try next without too much impact on cost.”

The trial is currently in Phase One, comparing different sized shred (200mm, 150mm and 200mm with 80mm ‘top dressing’). The roads are 50m long trial sections originating at the landing loadout bays. The best-performing particle size mix from Phase One will then be used in Phase Two, where roads of different depths, preparation and application methods will be put to the test. When complete, Pan Pac and FGR hope to produce a tech note (specifications, application method, and rough costings) on shred wood roads, which will be made available to the wider industry.

Pictured: Foresters from across the North Island watching a trial shred wood road being built in Pan Pac’s Mohaka Forest.