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38 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide and constraints noted within these regulations should be evaluated for their applicability to shared use. All railroad communications are subject to FRA Part 220, which mandates radio requirements, wireless communications procedures, and what to do in the event of commu- nications failure. . . . any train that transports passengers shall be equipped with a working radio in the occupied controlling locomotive and with redundant working wireless communications capability. . . . Safe and effective Command and Control requires that the communications network and transmission must limit access for safety and security purposes. Technology allows for a controlled flow of information between two or more key participants outwards to multiple subscribers through a central hub or between central hubs such as control centers of freight and passenger railroads. 3) Purpose of a Communications System One of the most important uses of communication is to back up or provide an alternate or supplemental means of train control in the event of failure or service disruptions. Whatever the technology, verbal communication remains the foundation of safe and efficient movement of trains. In the context of this report, verbal communications refers to communication either between a control center and/or supervisory personnel and the train operator or other staff. These requirements extend to work equipment on the right-of-way (ROW), MOW crews, or lone workers under specified circumstances. The focus here is on non-vital systems and methods for information transmission (data or verbal), the content of that information, and the resulting action. The human interface for send- ing, receiving or responding to that information merits consideration in the practical outcome of the transmission. 4) Functional Design of a Communications System In conventional railroad parlance, communications is considered non-vital but nevertheless essential. The communications system is supplemental to the train control system, augments it, and provides redundancy. This non-vital information is monitored and captured. Communica- tions data flows through four steps. A. Capture Information: Monitor, report status, conditions or events, digitally or verbally. The system operator may wish to capture certain types of data and will provide sensors or read- outs such as: Vehicle identification, location (direction and speed), condition; Signal status (display and health); Grade crossing warning system status; HAZMAT (hazardous materials shipment) information; Track clearance intrusion; and Hazardous event detectors (dragging equipment detector, hot box). B. Transmission via the Communications Backbone: Conveying information verbally or digi- tally from the capture device to the display device, using the communications backbone, either wired (including fiber optic and copper), or wireless. C. Display Information: Receive information and present or report it in an actionable format. Vehicles, control centers, and other monitoring devices and systems are typically equipped with status information displays and alarm/alerting systems. The status display simply pro- vides current information about a given device, or function.