A braced framework of timbers, piles, or steelwork , usually of considerable height, for carrying a railroad over a depression. There are two over the Cascade Locks, both of steel. The lower trestle (appr 300 feet long, 40 feet above Lock 13) was originally constructed by the Valley Line RR l880, a rail line now owned by the National Park Service and operated by the Cuyahoga Valley Scenic Railroad. The upper trestle (appr 875 feet long 70 feet above Lock 11) was built in l891 by Pittsburgh, Akron and Western RR. Since l990 it has been owned by Wheeling and Erie. The steel structure may have been built after the l913 flood when the stone piers were undermined. These stone piers still stand just south of the steel trestle.