The U.S. Department of Transportation’s (DOT) John A. Volpe National Transportation Systems Center (Volpe Center), under the direction of DOT’s Federal Railroad Administration (FRA) Office of Research, Development, and Technology (ORD), conducted a research study that evaluated the effectiveness of light-emitting diode (LED) regulatory signs at a passive highway-rail grade crossing. In this study, a grade crossing in Swanton, Vermont had its existing Grade Crossing Crossbuck (R15-1) signs and Advance Warning signs (AWSs) (W10-1) replaced with flashing LED-equipped signs. Vehicle speed profiles were measured at four locations on the northbound approach lane of the crossing in three phases: with the original signs prior to any changes at the crossing, after the LED enhanced Crossbuck signs were installed, and after the LED enhanced AWSs were installed. Daytime and night-time data samples were analyzed separately. After the LED enhanced Crossbuck signs were installed, test results showed: 1) a statistically significant decrease of 2.9-3.3 mph in mean vehicle speed at night at the four measurement locations and 2) improvements of 1.5%-2.5% in the rate of mean vehicle speed decrease for both the daytime and nighttime data sets.