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T&D > Programs Areas > Forest Management > Chip Trailers Program Areas
Chip Trailers

Photo of prototype chip trailer.


This was a FY 2006 project to look into alternative designs for chip trailers, or other ways to mitigate the issues with chip trailers operating on forest roads. With the increase in fuels treatment projects on the national forests, these projects tend to pull out smaller trees that are chipped on site and hauled to biogen facilities or other facilities that utilize wood chips.

Traditional forest roads were designed to handle log trucks which have a tighter turn radius and higher ground clearance. Chip vans require wider curves and less aggressive water dips. Also, their higher center of gravity causes concern on outsloped roads.

The San Dimas Engineering Program had a parallel project on Chip Van Access developing recommendations for engineering the roads to handle these types of vehicles. The Forest Management Program is looking at an alternative redesign of the equipment to handle existing roads. Either method will result in some costs, the issue is selecting the method that results in the lowest expenditures.

The first step in this study was to talk to contractors, foresters, and engineers to determine where the problems are and receive input on possible solutions.

The Deanes Sale on the Plumas NF was visited, and some of the issues identified were as follows:
  • Possum belly trailers allow the purchaser to haul more chips per load, but limit the ability to get into sites due to low ground clearance. The purchaser in this case may need to consider using regular box vans to haul chips.
  • An issue with both types of van is the increased turn radius required to access sites. Timber sale administrators and engineers need to be aware of this and have a way to determine what that requirement is when identifying landing access roads. In some cases, shorter vans may be required to navigate tight corners. In this case a roll-off, containerized system may be required to access and remove biomass.
  • Analysis is required in the planning process to determine when the cost of providing road access for chipping exceeds the value of the wood. This may be addressed with the future Harvest System Software project. That software will be intended to provide the ability to calculate harvest costs and compare them against road maintenance costs.
Click on the curve calculator link to access a calculator for determining the central angle, curve radius, and curve widening necessary for a curve and tractor-trailer combo. This is the same calculator in that can be found at the engineering site, except this is a web based calculator. A complete software program has been developed that allows the user to calculate both curve widening and rolling dip dimensions. The rolling dip calculator also has a function that will determine whether a given vehicle will be able to negotiate an existing rolling dip without hitting the ground. Select this link to go to the download page.

Photo of prototype chip trailer dumping a load.

Current Work

San Dimas has developed and built a chip trailer with the tracking capability of a stinger-steer log truck. The prototype utilized a standard 40' open-top ISO shipping container. This configuration allows the trailer to track like a stinger-steered log truck which means that no curve changes are necessary to get the trailer down existing forest roads. This trailer also maintains the ground clearance of a conventional log truck.

The design required the removal of the existing log bunks. Special sub frames were built for the front and rear container mounts. These sub frames secure the container onto the truck and allow the tractor-trailer to pivot similar to log bunks. A walking floor was installed in the trailer to facilitate unloading.

The prototype has been used on a variety of demonstration sites in Regions 2, 5 and 6.

View news article about the log truck.

In terms of commercialization, Western Trailer has developed an estimate for converting a 45 foot chip trailer body to the stinger-steered configuration. Their estimate is $56,000 and depends on the condition of the trailer and any required trailer modifications. Contact Clint Whitehead at Western Trailer for additional info: (208) 908-5246.

  • No wet kit on truck, if a wet kit is not needed, the price drops by approximately $3000
  • The trailer has scales
  • Log truck and trailer provided
Price Includes:
  • Standard chip trailer body (with blow in door, Halco wood byproducts walking floor, ladder, rear bumper, and tarp)
  • wet kit for tractor
  • 5th wheel
  • 5th wheel load cells
View additional images of the prototype

View field demonstrations photos

View Klamath NF demo videos: #1 #2 #3

View Chip Trailer briefing paper

To schedule a demonstration on your forest, contact Project Leader Dave Haston.

Acknowledgements: The success of this project is a direct result of actually building the prototype (instead of merely contemplating or discussing the concept).

The concept (converting a log truck for hauling chips) is not a new one - we have had many people tell us they had the idea but did not have the means or capability of building a prototype.

The full scale fabrication of this trailer was a direct result of Ervin Brooks - Erv insisted that we build the prototype. We are grateful for his input and encouragement on this project.