Current State of Segmental Bridge Design / Construction in Texas

Over the past three decades, the Texas Department of Transportation (TxDOT) and other Texas entities have used segmental bridge technology. In the early 1970s, Texas embraced this form of bridge construction with the first precast segmental bridge in the United States in Corpus Christi. Since then, Texas usage has included large precast urban viaducts in San Antonio and Austin, a large precast interchange in Dallas, and cast-in-place bridges over navigable waterways along the coast. Segmental bridge construction involves multiple precast or cast-in-place concrete elements joint together by post-tensioning. In Texas, cast-in-place segmental construction has typically used the balanced cantilever method with form travelers. Most of these bridges are three-span continuous structures of variable depth whose primary purpose is to carry a relatively long main span over what is usually a navigable waterway. The navigable waterways usually have a relatively large vertical clearance that requires a substantial amount of bridge approach to reach the requisite elevation with appropriate roadway profile grade. The approach spans typically involve prestressed concrete I-beam spans typical of most Texas bridges. In recent years, prestressed I-beam bridge construction has represented 50 to 60% of the bridges constructed with costs around $50 per square foot.