HRSI's patented GPS technology changed the way railroads unload ballast, for the better."
HRSI's P.L.U.S. (Programmable Linear Unloading System) involves pre-dump surveys taken before a train spreads ballast. This is done to confirm the locations of switches, crossings, and other fixed assets. A survey file is created for each ballast spreading assignment. Using GPS coordinates, the survey defines ballast spread and no-spread areas and indicates the desired amount of ballast to be spread. The train, made up of Herzog Automated Ballast cars, "provides the fastest, most precise and efficient means of spreading ballast," HRSI says.
But pre-dump surveys have always proved challenging in areas where GPS outages occur, "and that challenge remains when the train arrives to dump the ballast," HRSI notes.
HRSI, "determined to meet and beat that challenge," conducted research and development on a system that could back up the GPS signal, if lost, while maintaining dumping accuracy. Various types of sensors were tested; the end result is the new P.L.U.S./Smart Train Inertial System, which HRSI says is "a huge advancement in ballast train technology. GPS outages will no longer be a concern when dumping ballast. The same can be said of the pre-dump survey when utilizing the Herzog ProScan LIDAR (Laser Imaging Detection and Ranging) Truck to replace the manual survey. Now, whether dumping ballast through a tunnel or through the mountains, the HRSI ballast train will always maintain an accuracy that is second to none."