Key Features:

• Five-level Interchange
• Prestressed Concrete U-Beams and
  I-Beams
• Phased Construction

P.E. Structural provided structural design services for 12 bridges within Section 3 of the Southwest Parkway Project, a new 6-lane controlled-access toll road for NTTA. Section 3 comprises the Southwest Parkway (SH121) Interchange with IH-20 and SH183, which includes 5-levels of roadway with direct connectors, ramps and complementary bridges – 33 structures in all.

All bridge design conforms to AASHTO LRFD Specifications and TxDOT typical practice. PESC’s 12 bridges (two DC ramps, one mainlane and several frontage road bridges) are diverse in type, length and configuration. They incorporate aesthetic treatments to multi-column bents and feature integral sidewalks. Superstructures utilize both prestressed I-beams and U-beams. Some of the most challenging aspects of bridge design were extreme skews (beyond 60 degrees), tall drilled-shaft retaining wall abutments, phased construction, and inverted-T straddle bents with lengths up to 65 ft for DC ramps.

Cost-saving measures initiated by the PESC team include reconfiguring two FR bridges, the schematics for which had curved deck sections, so that they could be constructed much more simply as straight structures with curved striping. This solution eliminated costly cantilever beams at abutments to support the curved deck and developed a more efficient layout using all U-beams for a frontage road bridge originally envisioned as having a combination of exterior U-beams and interior I-beams. Estimated $950M Construction. Anticipated completion of construction 2012.

Related Links:

• www.ntta.org
• www.bentley.com