This statewide on-call project includes multiple packets of tight schedule hydraulic structure sizing. INDOT provides groupings or packets of structures within the LaPorte, Seymour, and Crawfordsville Districts to complete surveys and hydraulic sizing. The final product is then submitted to the respective District for its review and use for replacement structures. To date, all the structures have been 20 feet or less in width, thus classifying them as culverts.
Once the packets have been assigned, DLZ surveyors complete a cross-section through the structure, a cross-section downstream of the structure, and a bridge opening survey. These items are then incorporated into hydraulic models along with discharge data, drainage areas data, and hydraulic coefficients. A drainage area to the structure is determined based on the LiDAR data and available GIS information. The models are then run to determine if the existing structure sizing meets INDOT criteria for replacement structures. If so, a like-size structure is recommended. If not, a new larger structure size is recommended to bring the opening into compliance. Nearly all models are completed with HY-8 version 7.2 software with HEC-RAS used in some applications for the structure sizing.