ANALYSIS OF RAILROAD-HIGHWAY CROSSING ACTIVE ADVANCE WARNING DEVICES

The purpose of this study was to determine which one of three candidate active advance warning devices for use on roadway approaches to rail-highway crossings was the most effective. Each of the candidate devices, developed during a previous study, consisted of a primary message sign, a supplementary, WATCH FOR TRAINS message plate, and two 8-in. amber, alternately flashing beacons. The devices differed only in the configuration and message of the primary sign. The study was conducted at four sites where sight restrictions on the approach resulted in an insufficient safe stopping distance. The train detection circuitry at each site was modified to provide train activation of each advance warning device approximately 10 seconds before the activation of the at-grade warning system. Each test device was installed at all four sites. The results of the speed profile analysis during the activated state indicated that the alternately flashing beacons produce a significant decrease in vehicle velocity. Similar analysis, during the unactivated state, revealed that there was no significant difference in vehicle velocities resulting from the use of different primary signs. These results indicate that the test configuration that used a 48-in. standard (W10-1) railroad advance warning sign would be effective in providing motorists the required advance warning.