This is one I built with my Snowmobile Club. It's got 5- 14" power poles across the span about 35 ft. The decking is 2X12X14 Larch with we get from a local mill guy.
The runners stop wear from the Groomer drags tearing up the decking. The Groomers weight in 18,000LBS to 22,000 LBS without any flexing.
I did build on a 140 year old Railroad Tressel that had steel spanning the creek 40 ft long. We added a couple on power poles on it also. We bolted 2x8 on the steel with carriage bolts to be used as the nailer for the decking.
We do screw them with big lags/ construction screws
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