February 19, 2012
American Bridge was prime superstructure contractor for two new bridges, one roadway and one rail, to facilitate the widening of the navigation lock at Kentucky Dam. The two-lane roadway bridge is a 10-span, 3,116' (950m) steel plate girder structure with a main span of 505' (154m). The four and five lines of girders were erected in pairs using the drop in method, with picks up to 200 tons (181mt). These double crane picks were made by two barge-mounted 4100 Series II cranes with ringer attachments. At the main channel the haunch segments were each erected in two pieces, with a horizontal splice made in place. The main channel span was assembled using the drop in method. There was no single disruption to the navigation channel exceeding eight hours. The railroad bridge was erected span to span, in pairs and with double crane picks, except for the main 505' (153m) by 25' (with 4" thick flanges through truss channel span). This 2,200 ton (1,996mt) truss was assembled on a single falsework bent in a specially prepared nearby yard. It was erected by floating two 195' by 70' (55m by16.5m by 3.7m) barge assemblies with falsework towers and jacking platforms pre-erected. The truss was floated off its center falsework bent and to the erection point, and lowered onto its permanent bearings. The float-in was completed in an eight hour channel closure. There was also another 120' (37m) railroad bridge that was entirely replaced on the existing alignment in a 48 hour rail closure. To accomplish this, the piling and piers were constructed around the existing bridge without removing it from service, and the new span was constructed on adjacent falsework. During the closure, the old span was demolished and the new span translated transversely into place. American Bridge self-performed all steelwork and also 10,000CY (7,646CM) of cast-in-place concrete deck for the roadway and highway bridges. The railroad bridge and the highway bridge are each 3,116' long. The design engineers were Entran, Inc.; Hanson Professional Services, Inc.; Harrington & Cortelyou, Inc.