Determining the risk related to transportation networks due to the occurrence of (natural) hazard events often requires computer support. A simulation-based modeling environment can be useful when modeling a set of related events that lead up to the estimation of the probable consequences of hazard events, which affect network managers and society. Nonetheless, running such simulations can be computationally expensive because each type of event requires a model of its own, and proper interfaces are needed to link events. Therefore, only a limited number of simulations can often be conducted, with the expectation that their results are representative of those that could have been obtained if all simulations had been run. This article presents a simulation reduction technique to calculate the risk related to transportation networks due to extreme hydrometeorological hazard events by conducting statistical analysis on the risk estimated when simulating the impact of nonextreme events. The technique may be of interest to network managers seeking to make decisions based on possible future climate scenarios. An example road network in Switzerland is used to illustrate the technique. DOI: 10.1061/(ASCE)IS.1943-555X.0000530. © 2020 American Society of Civil Engineers.