A detailed report is required for any bridge replacement or rehabilitation project, or any roadway reconstruction project impacting floodplains mapped as Zone A (approximate) or Zone AE (detailed study with base flood elevations determined). The TxDOT document “ ,” describes the expected content of a report in this context. The report typically consists of an introduction, a hydrology description, description of hydraulic analysis and a summary of conclusions and recommendations.

The introduction describes the purpose of the project, the specific impacts on the stream crossing, and the purpose of the study. The hydrology section describes the watershed, including climate, soils, and other pertinent data, and identifies the methodology used to compute flow. The hydraulics section includes analysis of the existing structure or conditions and design alternatives as well as an overview of the hydraulic modeling process. The hydraulics section also discusses design alternatives and provides a preferred alternative.