The darkness seemed to stretch for miles. The smell of mold was nearly overwhelming. Water trickled down from the ceiling into pools on the floor. The constant whirring of bike chains echoed around the tunnel. Tara Wills and her son burst out of the dark train tunnel and into the open. It was good to be out of such an eerie passageway. They were taking a 20-mile bike ride near Fort Lewis, Washington, but that was nothing for Wills.