Tunnel (Big Arch Rd.) under RR tracks NE of Alton, Godfrey Township, Madison County, IL. Alby St. N. 0.3 miles from jct with MO3/111 (Homer M. Adams Pkwy) in Alton, E. on Big Arch Rd. 0.7 miles (to end) to the tunnel. On private property, ask permission. (2-23-06, N38 55.78 W90 09.90) Photo by Jack Schmidt.