The US experienced 308 weather and climate related disasters since 1980 exceeding $2.085 trillion in physical losses and the loss of 14,492 lives. Between 1980-2020 the average number of billion- dollar events per year was 7.1, that number ballooned to 16.2 billion-dollar events per year on average between 2016-2020 (adjusted for Consumer Price Index). The most billion- dollar weather and climate related disasters occurred in 2020, with 22 billion-dollar events totaling $246.7 billion in losses and 553 deaths. As of September 2021, the current year is looking to break the record set in 2020 having experienced 18 billion-dollar events to date (Billion-Dollar Weather and Climate Disasters: Overview | National Centers for Environmental Information (NCEI) (noaa.gov) ). In addition, the recently published TRB Consensus Study on Resilience Metrics notes that 6 of the world’s 10 most costly natural disasters in 2020 occurred in the United States (TRB Resilience Metrics Consensus Study, 2021). With this level of impact on the nation’s infrastructure, transportation agencies need consistent methods to support decision making to address stressors such as extreme weather and climate change in planning, design, maintenance, and operations.
The TRB Resilience Metrics Consensus Study 2021 calls for the establishment of standard methods of analysis to support benefit-cost assessment to allow agencies to understand the “buy-down” of risk from capital and maintenance investments. In addition, the study calls on Congress to consider requiring that all federal funding candidate projects that involve long-lived assets requirement undergo well defined resilience assessments that account for changing risks of natural hazards and environmental conditions stemming from climate change. The proposed project will allow AASHTO and TRB to develop industry adopted standard methods of quantitative analysis in lieu of federally developed methods.

Proposed Program of Projects

A concerted level of commitment from AASHTO and TRB is needed to develop a single manual to serve as the “go-to” for quantitative analysis of financial risk to agency assets and the traveling public from extreme weather and climate change. Like the Highway Capacity Manual and the Highway Safety Manual, a single resource is needed to ensure consistent methods of analysis between projects and agencies, and to ensure adoption of robust quantitative methods to support benefit-cost analysis and decision making. A single manual will allow state, MPO, federal agencies to compare project investments on a level playing field – same models, same assumptions, same thresholds of performance. A single manual will also support the instruction of how to address extreme weather and climate change in planning and engineering curriculum at Universities ensuring future Transportation Professionals are equipped with the skills needed to support the adoption of such methods into practice. Finally, a single manual will allow the incorporation of extreme weather and climate change considerations in Professional Engineering examinations to further institutionalize these concepts in future design and decision making.
This program will establish a series of individual research projects to support the development of a Highway Resilience Manual born out of NCHRP 23-09, Scoping Study to Develop the Basis for a Highway Standard to Conduct an All-Hazards Risk and Resilience Analysis and NCHRP 20-123(04) Development of a Risk Management Strategic Plan and Research Roadmap. Similar to other NCHRP research programs such as NCHRP 20-102, Impacts of Connected Vehicles and Automated Vehicles on State and Local Transportation Agencies, this is a long-term research program that will result in an industry “standard” for all-hazards risk and resilience analysis for use in design, maintenance, and planning decision-making. In addition, the program of projects will address required data sources and work to field test the Highway Risk and Resilience Manual with a range of agencies as described in the following three phased approach and in the draft Research Roadmap:

1. Phase I: Development of Highway Risk and Resilience Manual. An anticipated 3-year phase consisting of multiple projects and costing approximately $3,500,000. Year 1 estimated to cost $1,500,000 with years 2 and 3 estimated at $1,000,000 each. There would be multiple projects under this phase including five projects identified through NCHRP 23-09:
   • Establish quantitative assessment methodology for top priority threats and assets (e.g., culverts and flooding)
   • Develop historical data capture process quantitative analysis methods
   • Develop quantitative resilience assessment methodology
   • Establish performance metrics and thresholds for resilience and risk tolerance; provide guidance on reducing risk and improving resilience
2. Phase II: Implementation of Highway Risk and Resilience Manual. A 2-year, $2,000,000 program that would implement/apply the Highway Risk and Resilience Manual to 8-10 transportation agencies. A few potential projects in Phase II are outlined here:
   • Create internal and external agency communication and collaboration practices to incorporate Highway Risk and Resilience Manual in decision making
   • Develop capacity building plan to identify institutional and educational needs to incorporate Highway Risk and Resilience Manual into practice
   • Pilot test Highway Risk and Resilience Manual
   • Identify institutional organizational and procedural (IOP) changes and implementation strategies for the successful adoption of Highway Risk and Resilience Manual
3. Phase III: Development of Tools and Resources to Support the Highway Risk and Resilience Manual. A 2-year $1,500,000 effort to create automated, geospatial models that transportation agencies could use to implement the Highway Risk and Resilience Manual across networks or the transportation system.
   • Develop stand alone, open source computer script that can work within a GIS environment to automate Highway Risk and Resilience Manual calculations across multiple assets and threats in a geo-spatial setting
   • Develop spreadsheet-based tools to automate Highway Risk and Resilience Manual calculations across multiple assets and threats in a spreadsheet application
   • Selecting Performance Metrics for Evaluating Effectiveness of Risk Mitigation o Incorporating Risk Management into Maintenance Practice
   • Developing New Performance Metrics for Risk Management
   • Assessing the Impact of Common Risks on Federal Reporting Metrics

Transportation owners and operators are responsible for the transportation system and the delivery of a range of services and functions through the management of that system. There are inherent risks involved with the management of these systems, notwithstanding aging infrastructure, and fiscally constrained resources. Many agencies are moving toward performance-based resource allocation while simultaneously recognizing risks that may undermine their strategic goals. As these risks affect every component of a highway system to a greater or lesser extent, accurately accounting for and addressing these risks within a highway agency’s enterprise-wide management program is the goal which currently lacks analysis tools.
Investing in risk and resilience strategies and enhanced recovery to reduce or eliminate the impact of external events is also paramount to ensure a thriving, viable transportation system. Risk management requires the identification and assessment of potential threats and hazards, asset vulnerabilities from applicable threats, an evaluation of potential mitigation actions to reduce risk, a clear and easy to implement process to prioritize mitigation activities, and investment that aligns with agency strategic and performance goals. Asset management and more recently performance management, has been an ongoing focus of many research efforts. However, guidance for analytical risk assessment methods to support risk-based asset management processes is lagging. Risk assessment processes, methods, and tools are needed to integrate risk management into asset and performance management systems. In addition, an understanding of the relationship between risks and system resilience is lacking.
Basics needed:
• Adopted definitions
• Standard framework for quantitative risk based on expected financial losses to agency and traveling public
• Establishment of performance metrics for risk and resilience
• Suggested risk tolerance and resilience performance targets that agencies can customize
• Methods to incorporate climate projections into decision making
• Methods to analyze both deterministic and probabilistic input data (500-yr flood versus climate scenarios)
Future research can expand threats analyzed; assets analyzed; climate projections; life cycle cost; remaining life consideration of assets; environmental impacts, etc.