Driving simulators have great potential to enhance road safety, because they provide an opportunity to study driver behavior in response to new or revised roadway design features, prior to construction. However, this potential depends on the ability of behavioral data observed in a driving simulator to predict the true behavior that would be committed in the real world. The objective of this research is to fill this important gap by (1) developing transformations of simulator data so that it matches observed on-road behavior, and (2) identifying the level of simulation fidelity needed to address particular design issues. This is a large scale, three phase research program led by the National Advanced Driving Simulator program at the University of Iowa, on behalf of the FHWA Exploratory Advanced Research Program. Phase 1 starts with input from roadway designers and defines simulator characteristics that may be needed to address these issues. Phase 2 collects data to compare driver performance in a range of simulators to on-road performance. Phase 3 develops model-based transformations for relating simulator data to on-road data. WTI is part of the research team, with task responsibilities that include providing simulator resources and developing validation methodology.