Gulf Intracoastal Waterway Bridge, Matagorda, Texas


The Texas Department of Transportation recently completed a new segmental bridge (Fig. 8, 9 and 10) in place of an old, floating swing bridge that cost about $350,000 per year to operate. Segmental was chosen because it can span 320 feet, is durable and aesthetically pleasing. With adjacent side spans of 180 feet, the 46-foot wide segmental box girder unit runs for a total length of 680 feet.

The traditional form of the segmental box girder and column were altered to create a more cohesive visual connection between column and superstructure. The typical flat-bottom shape gradually gives way to a v-hull shape as it approaches the columns. The bevel is then carried directly into the columns with the same 3:7 bevel to form a perfectly mitered corner. The main piers have a unique double-anchor shape that continues the heavily chamfered appearance of the superstructure. The tips of the anchors curl around to protect and hide light fixtures that illuminate an internal web.

One unusual aspect of construction was the bottom soffit form. Flexible, rotatable “wings” mounted on a central spine allowed for an ever-changing bevel to be cast. In fact, the entire system was designed such that it could be warped. A portion of the forms was clamped to the underside of the previous segment while the leading edge, located 15 feet forward, was opened to a wider angle.

Project Details








Midwest Foundation Corporation

Contractor Engineering Services:

Summit Engineering Group, Inc. & Frank W. Neal & Associates

Construction Engineering Inspection:


Form Travelers for Cast-in-Place Segments:


Post-Tensioning Materials:


Prepackaged Grout:


Bridge Resources