The 20-foot portable skidder bridge at Siuslaw Model Forest in Acra, NY was rotten and needed to be replaced. The bridge is one of 10 examples of forestry best management practices (BMPs) on display at Siuslaw. BMPs are cost-effective ways to increase sustainability and reduce problems associated with the management of forests and other natural resources, such as soil erosion. The lumber required for the job was already on site, Siuslaw just needed a hand with the construction and placement of the bridge.
In July 2021, I called B&B Forest Products Ltd., located 5 miles down the road in Cairo, NY, to see if they could help, and if so, to obtain a quote. I explained the situation to owner Bill Fabian and he offered to put the bridge together and install it free of charge! I was humbled by Bill’s willingness to help. He said they had a machine, called the FastMat Drill, that could put portable skidder bridges together in under 10 minutes. Knowing how much work it takes to put them together manually, I had to see Bill’s operation.
First, the bridge cants were laid out in preparation for drilling:
These nine white oak cants make one skidder bridge panel measuring 4.5 feet wide and 20 feet long. To accommodate the width of a skidder, three panels are placed side by side to make a bridge 13.5 feet wide. For a better visual, check out this skidder bridge spec sheet.
Next, a wheeled loader placed the bridge cants on the workbench:
The loader gave the cants a nudge and a ratchet strap held the cants together tightly during drilling.
The FastMat drilled through 4.5 feet of white oak at seven locations along the 20-foot bridge length.
The FastMat drill being used to make one of seven holes along the 20-foot bridge length.
The holes were countersunk on both ends to accommodate 2.5-inch washers. The FastMat drill does this automatically on its side of the bridge. In fact, countersinking on both sides of the bridge is unnecessary for bridges built to FastMat specifications. In this instance, we already had lumber cut and the associated hardware for a different set of specifications and Bill was making due. This led to several extra steps, but Bill and two of his colleagues still managed to put together two panels in about 1.5 hours. Here is a good example of what bridge panel construction would normally look like: https://www.youtube.com/watch?v=Pn03kFNzi2E&t=354s
Bill countersinking one of seven holes with a hand tool.
One-inch threaded steel rods were inserted into each of the holes and tightened with nuts and washers:
Adding the one-inch threaded rod.
Tightening the bridge cants.
Seven rods tightened down.
Lastly, a handheld circular saw was used to trim the excess threaded rod so the ends were nearly flush with the outer bridge cant. Note this step is also unnecessary when building to FastMat specifications.
Trimming the excess threaded rod.
One completed bridge panel. Note the one short cant in the middle, which leaves the threaded rod exposed. This allows for a cable skidder to hook up to the bridge panel.
On behalf of CCE Columbia-Greene, the WAC Forestry Program would like to thank Bill Fabian and B&B Forest Products Ltd. for their donated time and effort in constructing this bridge. Stay tuned for a future blog that documents the removal of the existing bridge and installation of the new one.