Keywords: Seismic risk assessments (SRA). Highway infrastructure. Highway systems. Risk of Earthquake Damage for Roadway Systems (REDARS) software program. Post-earthquake analyses. Ground motion. Bridge fragility models. Traffic state models. Transportation network models. Economic loss models. Uncertainty.
Abstract: This report represents the results of an extensive review and evaluation of the Seismic Risk Assessment (SRA) methodology for highway systems documented in Werner et al. (2000). The research team evaluated the efficacy of all key modules in the REDARS (Risk of Earthquake Damage for Roadway Systems) software program. The modules included bridge damage or fragility, post-earthquake traffic state, transportation, and economic loss. The reader should note that the version of REDARS evaluated in this study has since been updated based largely on the conclusions and recommendations of this report. Some of the key recommendations identified in the study include: 1)uncertainty factors in the bridge fragility module, 2) additional events – beyond the 1994 Northridge earthquake – should be incorporated in the validation and/or calibration of the different loss modules, 3) further investigation of the traffic state model, particularly, in the relationship between link importance and duration of bridge closure should be conducted, 4) the travel demand model should be enhanced so that congestion level becomes a critical factor in establishing demand, 5) a more realistic post-earthquake route choice model should be developed, and 6) other significant cost items should be included in future enhancements of REDARS.