Tue, 06/15/2004
Technical Release

Chips: trailers

INTRODUCTION: Most FRA member company wood products facilities either ship or receive wood chips, bark, fuelwood, and similar products by truck. At many of these facilities, truck drivers spend a considerable amount of time climbing on vans to pull tarps over open-top trailers. Some facilities have designed and constructed drive-alongside tarping stations to eliminate the need for truck drivers to climb onto their trailers to secure tarps.

Fig. 1: Tarping station at a Virginia sawmill.


Before weighing out, a loaded chip or bark trailer pulls alongside the tarping station. The driver exits the cab and walks up the stairs to the trailer-length catwalk. From this vantage point, the driver can easily roll the tarp over the loaded trailer from the safety of the catwalk. The "solid roll" type of tarp, with a center drawstring, works best. After the driver is satisfied that the tarp is placed correctly, he or she walks down the stairs to ground level to secure the tarp.

Fig. 2: Tarping station at a North Carolina engineered-wood facility.

In some setups, the truck driver actually steps from the platform onto the top of the chips in the van and pulls the tarp over the load while he or she is connected to a harness (and tether) to prevent him-or herself from falling. (Some locations do not provide a harness; while it may look safe for the truck driver to step from the platform to the top of the materials in the van, the truck driver must pull the trailer very close to the catwalk, and the catwalk must be approximately the same height as the top of the trailer, or it can be unsafe.) 

 Fig. 3: Catwalk is approximately the same height as the top of the trailer.
(South Carolina sawmill location)


This station eliminates the need for the driver to climb the chip trailer's ladder and risk falling. The tarp can be spread more evenly over the load in a safe manner, and the overall time needed to complete tarping is reduced.

Fig. 4: This Virginia sawmill/chip mill's tarping station includes a safety
harness and chain tether for the truck driver . . .


Specifications will vary with the style of tarping platform. Here are some general observations.

Fig. 5: . . . who must walk on top of his load to spread the tarp.

The platform should be 45 feet or longer to handle the largest open-top vans. The stairs and catwalk are generally made of expanded metal (diamond pattern), but sometimes 1-inch by 4-inch metal grating is used instead of expanded metal. The catwalk is about 13 to 14 feet high-close to the level of the trailer top. The platform frame is made from 3-inch by 3-inch square tubing, with 2