Interoperable positive train control

There has been a substantial interest in developing an interoperable communication-based train-control system (TCS) for decades. The initial effort started almost 25 years ago with the advanced TCS (ATCS) efforts. This was an industry-driven effort to define a new form of train control. Unfortunately, it relied on large, central, computing-based systems, which have proven impractical for train control. However, some good work came out of this effort in terms of an addressing scheme that allows unique identification of every piece of equipment (e.g., switch or signal) in the country. A communication datagram structure also came out of this project that has been widely used in the industry.