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CHAPTER 3 Enabling Shared-Track: Technology, Command, and Control Introduction The technology essential to enable shared track operations encompasses Command and Con- trol systems, signal and train control, communications, and vehicle technology. The choices are influenced by economic and regulatory considerations. Technology options impact the business and safety cases. This section reviews the variety of train control systems, communications systems, operational Rules and Procedures, and vehicles that are particularly suitable or adaptable to the shared-track environment. The emphasis is on those features or characteristics that will compensate for vehi- cle structural deficiencies by minimizing the risk of a collision or mitigating the effects in such an integrated system. Above all, this combination of features and capabilities will have to fulfill the FRA safety mandates. Achievement of those objectives does not imply that all systems and vehicles should be FRA- compliant. Rather, they must satisfy Federal guidelines and conform to jurisdictions and princi- ples established in the 1999 joint FRA/FTA policy statement, which were subsequently codified in current regulations, 49 CFR Parts 209 Appendix A and 211 Appendix A. Under these require- ments, the FRA must be satisfied that all technical and operational aspects of the proposed shared- track system are sufficiently safe prior to authorizing revenue service. A survey of operational and proposed systems, summarized in Chapter 4 (performed for the Task 5 Report), strongly suggests that a fail-safe train separation system and intrusion detection in high risk areas are critical, and a necessary prerequisite to concurrent shared-track operations. The importance of autonomous collision prevention is amplified when the vehicles involved have disparate structural capabilities, speeds, or weights. The Role of Command and Control Systems in Shared-Track The growth of shared-track applications in the United States is dependent upon the evolution of fail-safe Command and Control systems that provide no ambiguity, overlaps or gaps in author- ity, misunderstanding or disagreements among users. It is important that the research establishes minimum requirements of Command and Control systems for shared-track operations and rec- ommends potential enhancements to assure the safety of all users. Command and Control can be seen as a triangular relationship of elements that, when prop- erly integrated, improves safety and supports operational requirements and passenger and freight service objectives. The elements are: 27