The Federal Railroad Administration is interested in understanding the effect of warning reliability on motorist compliance to warnings at active grade crossings. The John A. Volpe National Transportation Systems Center conducted two studies to examine motorist behavior as a consequence of warning signal failure. Experiment one measured motorist behavior in response to false alarms (i.e., the presentation of a warning when no train was approaching). Experiment two examined how motorist responses to grade crossing warning signals were influenced by false alarms and missed signals (i.e., the failure of the warning system to signal an approaching train).