  This paper develops a test scenario specification procedure using crash
sequence analysis and Bayesian network modeling. Intersection two-vehicle crash
data was obtained from the 2016 to 2018 National Highway Traffic Safety
Administration Crash Report Sampling System database. Vehicles involved in the
crashes are specifically renumbered based on their initial positions and
trajectories. Crash sequences are encoded to include detailed pre-crash events
and concise collision events. Based on sequence patterns, the crashes are
characterized as 55 types. A Bayesian network model is developed to depict the
interrelationships among crash sequence types, crash outcomes, human factors,
and environmental conditions. Scenarios are specified by querying the Bayesian
network conditional probability tables. Distributions of operational design
domain attributes - such as driver behavior, weather, lighting condition,
intersection geometry, traffic control device - are specified based on
conditions of sequence types. Also, distribution of sequence types is specified
on specific crash outcomes or combinations of operational design domain
attributes.
