Conference PaperThe improvement in transmission resilience metrics from reduced outages or faster restoration can be calculated by rerunning historical outage dataAhmad, Arslan [Iowa State University,Ames,IA,USA]; Dobson, Ian [Iowa State University,Ames,IA,USA]; Ekisheva, Svetlana [North American Electric Reliability Corporation,Atlanta,GA,USA]; Claypool, Christopher [North American Electric Reliability Corporation,Atlanta,GA,USA]; Lauby, Mark [North American Electric Reliability Corporation,Atlanta,GA,USA]Transmission utilities routinely collect detailed outage data, including resilience events in which outages bunch due to weather. The resilience events and associated metrics can readily be extracted from this historical outage data. Improvements such as asset hardening or investments in restoration lead to reduced outages or faster restoration. In this paper, we show how to rerun the historical events including the effects of the reduced outages or faster restorations to measure the resulting improvement in resilience metrics, thus quantifying the benefits of these investments. This is demonstrated with case studies for specific events (a derecho and a hurricane), and all large events or large thunderstorms in the Midwest USA. Instead of predicting future extreme events with models, which is very challenging, rerunning historical events readily quantifies the benefits of resilience investments if these investments had been made in the past. Rerunning historical events is particularly vivid in making the case for resilience investments as it quantifies the benefits for events actually experienced, rather than for uncertain future events.IEEE2025-07-27106740641 to 5979-8-3315-0995-8https://doi.org/10.1109/PESGM52009.2025.112257042153163National Science Foundation