Approval of AASHTO Ballot Item Related to Probability Based Evaluation of Foundation Movements

Today (June 26, 2019), at the General Session of the Annual Meeting of Committee of Bridge Structures of the American Association of State Highway and Transportation Officials (AASHTO) in Montgomery, Alabama, a ballot item related to service life design of highway bridges was approved. This work is a product of Project 12-108 of the National Cooperative Highway Research Program (NCHRP) which developed “Guide Specification for Service Limit State Design for Highway Bridges.” For this NCHRP project, led by Modjeski and Masters, Inc., a rather innovative approach to integrate product-specific diverse “deemed-to-satisfy” durability (deterioration mitigation) guidance for foundations and retaining walls was developed led by Naresh Samtani. A novel 3-tier Protection Index approach has been developed that encompasses all the foundation and retaining wall protection strategies. This approach combines ascertainment of risk and selection of protection strategy. In this system, a Protection Index value is established based on the environment, consequences of adverse performance, location, and type of facility carried or protected. The main features of the protection index approach are (a) division of design into three categories based on a number of “risk” factors, and (b) scaling of the risk mitigation through  appropriate protection strategies. The NCHRP report will be issued in July 2019 and the Guide Specification will be published soon by AASHTO. Updates on these activities will be posted on this website. Stay tuned for more details …… Thank you for your support!