Assessment and Reduction of Transportation Structure Vulnerability: Past, Present, and Future

Following the events of 9/11/2001, FHWA together with AASHTO commissioned a Blue Ribbon Panel (BRP) on Bridge & Tunnel Security. It was charged with the task of examining the issues and developing the initial road map for improving the bridge and tunnel security in the United States in the face of this new reality; organized terrorism on American soil. The recommendations of the panel was published in September of 2003, and has been a key reference and a source document for assessing vulnerability and planning of structural hardening of many key bridge and tunnel facilities in the US. Even though a considerable knowledge existed in related areas, especially within the military type organizations, at the time the BRP, bridge and tunnel security was in its infancy. Over the decade since 9/11, much progress has been made in both infusing the considerable knowledge that existed in other areas. These include counter terrorism intelligence, monitoring and enforcement as well as structural hardening and blast resistant design applied to military buildings and other facilities of sensitive nature. In addition to this cross-over of operational and design methodologies, considerable new knowledge and experience in vulnerability assessment and mitigation has been generated specific to bridges and tunnels. One key aspect of this evolution is the crystallization of the idea that any holistic vulnerability assessment and risk mitigation of the transportation infrastructure must consider multi-hazards and just not terrorism. However, many challenges and considerable difficulties still remain in improving safety and security of many existing bridges and tunnels to a meaningful level. The paper examines the evolution of bridge and tunnel security, the progress to date and also the challenges and opportunities as we as look to the future in developing promising new approaches and initiatives. It can be shown that viable approaches are available to bring bridge and tunnel security to the next level in a cost effective manner in a relatively short time; same way how the earthquake security initiative of the 70's improved the seismic worthiness of bridges and tunnels in America and beyond.