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Title:Reducing Flood Vulnerability of Communities with Limited Road Access by Optimizing Bridge Elevation
Authors:David Turner, John W. van de Lindt, and Bolivar Senior
University:Colorado State University
Publication Date:Oct 2020
Report #:MPC-20-423
Project #:MPC-448
TRID #:01763113
Keywords:bridge design, bridge superstructures, failure, floods, risk assessment, rural areas
Type:Research Report – MPC Publications



On September 11-17, 2013, Colorado suffered devastating and widespread flash flooding over 150 miles from Colorado Springs north to Fort Collins, impacting 24 counties. The flood damaged several bridges and over 400 miles of state roads. As a result of the transportation damage, residents of Drake, Colorado, were isolated and had to be evacuated via helicopter. This thesis aims to determine the failure risk associated with the inundation of bridge superstructures.

A linear network of eight bridges near Drake, Colorado, was selected for analysis, which includes three unique structural configurations. Flood analysis was performed using the design equations presented by Kerenyi et al. (2009), which follows the same equation format listed in AASHTO. Fragilities were developed for the most critical internal and external composite girders for each bridge. The results obtained from fragility analysis were then used to determine the elevation adjustments needed to reach a target beta value of 3.5. Based on the analysis conducted in this thesis, it was found that the forces associated with bridge deck inundation, more specifically, in fast-moving mountain rivers is substantial and must be considered in design. Currently, bridge superstructures are designed based on the 100-year flood, which in the case of the bridges in this study, would not have resulted in any inundation of the bridge deck at the time of construction based on the knowledge at that time. To counter this, bridge superstructures should be designed based on the 500-year flood, which would incorporate inundation forces in the initial design. The methodology presented in this thesis can be used to assess and improve the flood vulnerability for any communities' bridge network.

How to Cite

Turner, David, John W. van de Lindt, and Bolivar Senior. Reducing Flood Vulnerability of Communities with Limited Road Access by Optimizing Bridge Elevation, MPC-20-423. North Dakota State University - Upper Great Plains Transportation Institute, Fargo: Mountain-Plains Consortium, 2020.

NDSU Dept 2880P.O. Box 6050Fargo, ND 58108-6050