State Highway 550 / US 77 Toll Road

As a subconsultant for this new toll road project (from US 77/83 to FM 3248),  S&B Infrastructure, Ltd. (S&BI) provided a new entry point for truck traffic to the Port of Brownsville. This project involves providing Plans, Specifications, and Estimates (PS&E).


S&BI also developed bridge layouts and design for the northbound and southbound direct connectors at SH 550 / US 77, including summaries, foundation design, strucural detailing (slab plans, abutment and bent details, foundation plans and layouts, etc.), specifications, and estimates.


The bridge provides a direct connection between SH550 and US77 in both south and north bound traffic. The total length is about 3370 feet, with varied width 38’ to 79’.


Superstructures are prestressed concrete beams over the streets and curved steel plate girders over US77. Regular hammer head and specially designed post-tension concrete cap are used as bent structures.


The curved steel plate girder, (3-span, 508 feet long) is supported on four different skewed bents, with skew angle equal to 0, 36, 58 and 0 degree.


The different skew angles of bent cause different span length of the plate girder and different rigidity of girder, hence the complicated stress on curved plate girders and the diaphragms between girders. With the straddle bent spans are over 57 feet long and the hammer head bent cantilever 27.5 feet, the bent caps have to be designed as post-tensioned reinforced concrete structures. S&BI also developed pavement marking and guide sign layouts, and traffic control plans.

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