 The Boylston Tunnel was also known as the Johnson Creek tunnel to the railroad and sometimes tunnels #46 and #47 are known as the Thorp Tunnels.Access points to the undeveloped portion of the trail, managed by Washington State Department of Natural Resources, have not been formally opened to the public.However, the trail provides access to the unique geological erosion features of the Channeled Scablands regions of the state of Washington, and several stretches have been recognized as providing access to this area created by the cataclysmic Missoula Floods that swept periodically across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch.