Many state DOTs
Holly Yaryan Hall, Brian Bledsoe, Rod Lammers
Traditional designs for roadway stream crossings are based on hydraulic capacity, while natural channels convey both water and sediment. Furthermore, culverts and bridges are typically designed for a single large storm event (e.g., 25- or 100-year flood), while the bulk of sediment transport takes place over the course of more frequent low to moderate flow events. Since many transportation agencies simply do not account for sediment transport, we may expect to encounter problems with aggradation, degradation, and other types of channel instability. Such oversight costs time and money in the long run by simultaneously increasing channel maintenance requirements and risk of infrastructure failure. NCHRP Project 24-40 aimed to help designers find balance by integrating sediment transport into stream crossing assessment and design. The University of Georgia partnered with transportation departments in Maryland, Minnesota, and Oregon to present three regional workshops between June 2019 and July 2020 to operationalize the research findings from NCHRP Project 24-40.
The goals for this project included products and activities to facilitate implementation of research results. The target audience included engineers tasked with assessing and designing road crossings (e.g., bridges and culverts), engineers tasked with designing or restoring stream systems in the vicinity of road crossings, and staff from regulatory agencies who issue permits for these types of projects. Workshop participants were provided with hands-on-experience using previously developed tools and new training materials (including regional examples), which will serve as practical resources for future individuals seeking guidance on stable channel design.