Advanced Methods for Performing Vessel Collision Risk Analyses for Bridges Over Navigable Waterways

Abstract: Recent tragic events in Baltimore, MD have highlighted and demonstrated the potential vulnerability of major bridge crossings over navigable waterways to catastrophic collapse due to extreme event loads such as vessel collision. The presentation will discuss ship and barge collision with bridges over waterways using lessons learned from historical accidents worldwide; analysis procedures outlined in both the American Association of State Highway and Transportation Officials (AASHTO) LRFD Bridge Design Specifications, 9th Edition, 2020 and the AASHTO Guide Specifications and Commentary for Vessel Collision Design of Highway Bridges, 2nd Edition, 2009 (AASHTO Codes) for both new and existing bridges; and application of ship and barge collision risk analysis procedures to complex navigation channel geometries (bends and turns) near bridges over waterways, water elevations and scour for risk analysis, consideration of bow crushing in the development of bridge substructure and protection, and risk analysis protection factors.

The presentation will also address how basic AASHTO Code provisions can be adapted to model the following modern challenges: large tidal fluctuations; Vessel Traffic Service (VTS); electronic navigation aids (AIS, GPS, ECDIS, etc.); Port State Control (PSC); multiple pilots; navigation transit restrictions; superstructure collision with masts and deckhouses; FEM analysis of ship grounding; contact of ship flared bow with bridge pier above the waterline; accident base rate of cruise ships; and advanced risk modeling techniques. The presentation will discuss examples and highlight lessons learned from recent vessel collision risk analyses performed by the authors for both new and existing long-span bridges worldwide.

The presentation will include dramatic images of historical bridge collapses worldwide due to ship and barge collisions and illustrate recent advances in the analysis of existing and proposed bridges to estimate the risk of collision and the design loads associated with vessel impact. Highway and rail bridges that cross busy navigation channels near coastal ports and inland waterways pose unique risks to a nation’s critical transportation infrastructure, and potential collapse due to vessel collision often lead to loss of life and significant economic and political consequences. Conference attendees will have an opportunity to see examples of historic bridge collapses, understand modern methods of evaluating the risk of collisions and the development of bridge protection systems to minimize the risk or consequences of vessel collision.

Note that for this presentation, author opinions or specific details associated with the 3/26/2024 vessel collision and subsequent collapse of the I-695 Francis Scott Key Bridge in Baltimore, MD will not be discussed due to ongoing State and Federal investigations.

How does this project / topic contribute to the advancement of the industry and profession?: The authors believe that this topic is of critical importance to both industry and professional individuals alike. Recent tragic events in Baltimore, MD have demonstrated the potential vulnerability of major bridge crossings over navigable waterways to catastrophic collapse due to vessel collision. It is anticipated that the presentation will provide both a basic understanding of risk assessment procedures as defined in the AASHTO Codes, as well as applicable advancements/techniques that have been recently developed by the authors for use in analyzing several “non-typical” situations that are not explicitly provided in the AASHTO Codes.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: Yes, highlighting lessons learned from vessel collision risk analyses performed for both new and existing long-span bridges worldwide, the presentation will discuss recent innovative advancements/techniques developed by the authors for use in estimating the risk of collision and design loads associated with vessel impact.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: The most challenging technical aspect of this topic has been the necessary continual advancement of existing AASHTO Code equations and procedures that were initially developed in the late 1980s for how to address risks associated with vessel collision on highway bridges. These groundbreaking procedures from the 1980s were originally published in the Guide Specification and Commentary for Vessel Collision Design of Highway Bridges, 1991. Industry advancements in risk analysis procedures (such as Monte Carlo simulations), general computing processes, and the availability of valuable information since the original implementation of the AASHTO Codes has led to a need for improved methodologies.

Who is the target audience for this paper?: Recent tragic events in Baltimore, MD have highlighted the importance of this critical topic. Therefore, the target audience for this paper would consist of many individuals, including design engineers, port planners, marine terminal operators, and policy makers that will benefit from a basic understanding of how risks associated with vessel collision with highway bridges are typically developed as well as technical refinements to the risk analysis procedures as developed by the authors.