Natural hazards, risk, and the resilience of transportation infrastructure: an example of risk-based geotechnical asset management

The Colorado Department of Transportation (CDOT) has recently implemented a Risk-Based Transportation Asset Management Plan (RB TAMP) that incorporates geotechnical assets and hazards. CDOT’s RB TAMP includes an ancillary wall structures program that includes all earth retaining structures, and a geohazards management program which is used to manage multiple hazards related to slopes, embankments, and roadway subgrade. The RB TAMP states multiple performance goals to be achieved, including safety, infrastructure condition, reliability, congestion, and maintenance, and the state will measure and report progress in these areas. Natural hazards, physical failures, external agency impacts and operational risks are risk types that present threats to CDOT’s achievement of their goals. The way these risks act on assets to impact performance goals can be visualized in a cubic form, and this allows for recognition of how many elements of risk there are, for making explicit decisions on which risks to address and how, and for communicating these decisions to others. Risk analysis at CDOT includes both qualitative and quantitative approaches in accordance with data availability. The quantitative estimate of risk is expressed in terms of exposure cost for all assets, risk types and performance goals and then used by CDOT subject matter experts for project selection and planning. The estimated risk exposures are also categorized into Level of Risk grades that are used to concisely communicate risk levels to executive management and to compare the long-term performance risks between asset types under different funding scenarios in the RB TAMP.