An evaluation was performed of special X-box pavement marking configurations at railroad-highway grade crossings, originally used in several European countries. The intent is to provide motorists with supplemental visual cues about whether sufficient space is available for safe storage of a vehicle beyond the track for a motorist to proceed across. It is intended for application where nearby intersections can cause queues to back up to the track. These conspicuous markings, configured as an X in a box, were tested at two Florida locations, one in an urban area and one in a rural area, over a 1 1/2-year period. The rates of cars hazardously stopping on or closely adjacent to the railroad tracks at the crossings were compared under pre- and postinstallation conditions. Results at the rural location showed a decline of more than 60% in hazardous stoppage rates over an extended period. No significant differences were found between the pre- and postinstallation tests at the urban location. A control site was utilized near the crossing in the urban location, and it showed no significant differences between the two test periods that were concurrent with the analysis at the treated site. Recommendations are provided for application of these markings at grade crossing sites in rural and urban locations.