Archer Western demolished an existing single steel truss bridge and replaced it with twin, cast-in-place segmental bridges that measured 1,916 linear ft over Lake Marble Falls in Texas. The bridge’s unique geometry called for careful advance coordination between the contractor and the formwork subcontractor. The distinctive feature on this project is the overall V shape of the bridge. The bottom of the bridge starts with a deep V that tapers to a very flat V at the apex or center span. This required a form that was flexible in all directions to accommodate the different span lengths at the varied box depths of the project, since no two segments were the same. The bridges were built using the balanced cantilever construction method with end spans constructed on falsework. The segments have a box depth that ranges from 23 ft at the interior piers to 9.5 ft at the center and end spans, with a variable super elevation up to 5.5%. Each segment weighed a maximum of 150 tons. This is the second-

US 281 Cast-In-Place Segmental Bridge over Lake Marble Falls

Marble Falls, Texas

Key Players
Texas Dept. of Transportation
Lead Design Firm Finley Engineering Group
General Contractor Archer Western Contractors