 The western half , however , was purchased by the Illinois Department of Natural Resources as a " satellite area " of Apple River Canyon State Park . The <unk> installed a new steel gate to replace the chain @-@ link fence covering the western bore , and is developing the area with nature trails and other improvements . However , the tunnel is currently off @-@ limits to general public visitation , as it is a very dangerous place to visit , with the ever @-@ present danger of further collapse and <unk> bite . 
