TxDOT US 59 Widening
Designing for Growth in the TxDOT Houston District
Due to increases in regional development and truck traffic, TxDOT widened US 59 to convert it from a rural highway to an urban freeway. Within the project limits, which extend from the Wharton County line to east of Darst Road, the existing roadway was widened to the inside to provide shoulders.
KFA served as staff augmentation for the Houston District to lead drainage design services for the hydrologic and hydraulic analysis completed for this project. We performed hydrologic and hydraulic analyses for the design storm events to determine drainage impacts for the proposed improvements. There are two cross structures within the limits of the project: a 10-foot by 7-foot reinforced concrete box culvert and a bridge over Brooks Branch. We developed an analysis of the existing drainage systems and flooding problems in and around the project limits, recommendations and analysis for the proposed conditions, and recommendations for mitigating the increase in impervious cover, floodplain fill grading to mitigate bridge piers, and corresponding increases in flow.
A TxDOT-approved mitigation option that maximizes storm sewer and/or roadside ditches for conveyance and mitigation volume is “best fitting” in the proposed typical section and using the in-system storage of oversized facilities or restrictor structures before outfalls. KFA used this method to create inline detention ponds in the median ditches along US 59 to contain flow in the limited ROW.
KFA’s drainage study helped TxDOT develop design plans for the project. The completed widening project provided shoulder safety widening and capacity improvements along the US 59 corridor.