The road that runs along the SF is the 4100 rd. The road is usually not gated until 10 miles or so. The sign that reads chip trucks only, is for going left and heading towards the mill. If you veer to the right the road will put you on the 4100 rd. Here is a info # for Weyerhaeuser that will give you upates on what roads are open: (360)425-2150. A Weyerhaeuser St. Helens Tree Farm map is very helpful. You can pick one up at most of the gas stations in the area.