County Road 123 (Avenue H) Over Corner Bayou Bridge-Class Off-System Culvert Replacement

IEA prepared plans, specifications, and estimates, and related documents for an off-System culvert replacement design at County Road 123 at Corner Bayou for Brazoria County Engineering Department.

IEA’s services for County Road 123 included the preparation of roadway, bridge, and hydrologic and hydraulic (H&H) design and environmental, geotechnical, and survey services. The existing crossing of County Road 123 at Corner Bayou consisted of a series of Corrugated Metal Pipes that conveyed water from the bayou as well as adjacent ditches. Due to the eroded condition of the crossing, the existing structure needed to be replaced.

County Road 123 was the only road feeding a small neighborhood of homes. As a result, maintaining traffic access was critical. The IEA Team performed alternative analysis and collaborated with the County to determine the best approach to maintain safe conditions during construction within the tight Right-Of-Way. As a result, a temporary access route was selected, and total closure was made feasible. To determine the best structure type for such a short crossing, IEA performed an Environmental Study to identify any wetlands or endangered species that would constrain design. Additionally, IEA conducted a drainage impact analysis to ensure the proposed structure would not create any impacts upstream or downstream of the crossing.

IEA performed an alternative bridge-type analysis to evaluate several options, including prefabricated bridge, conventional bridge, and precast culverts. The results of the environmental study and drainage analysis showed that precast box culverts would be more cost-effective than a bridge for such a short crossing and would minimize any impacts to the adjacent roadway. The IEA Team designed the concrete headwall and grading to fit within the right-of-way. IEA utilized current standards for low-speed traffic rail, metal beam guard fence, and safety end treatments in our design to enhance safety.