BCMs which fall out of range of locomotives are removed from talk path routes within the WCM in favor of the BCMs which are coming into range. In this way the WCM is constantly aware of where each locomotive is located and which talk path is best used to communicate with the locomotive. Such information is also conveyed to the office so that office systems may make use of it. Another aspect of redundancy is the system design which looks forward along the track, acquiring TSRs for the future in the event a temporary communications failure occurs. Since each locomotive has TSRs for at least three future segments of the rail line, in the event there is a segment of the track which for some reason has lost radio communication to the office, the locomotive has TSR information for the "dark" segment already before it proceeds into the dark segment. In the event of a loss of all redundant standby systems (such as might occur due to a wide area power failure or communications failure with the central office) the system will indicate to the locomotive engineer that it has lost the ability to enforce temporary speed restrictions, but the permanent restrictions loaded into the on-board database will continue to be enforced. Finally, the cab signals are considered a completely independent system that transmits a continuous stream of codes through the rails instead of via wireless transmission. Any fault in the ACSES overlay will not affect the cab signal system and moreover a cab signal failure will not affect the ACSES system. Without cab signals ACSES will continue to enforce positive stops at absolute signals, all permanent and temporary speed restrictions and a positive stop at any signal at the entrance to cab signal without fixed wayside signal territory that is not displaying "Clear to Next Interlocking." If a locomotive is unable to automatically retrieve temporary speed restriction information, permanent speed restrictions will continue to be enforced. In the event of a total failure of the on-board ACSES system the engineer may revert to the use of the cab signal system without civil speed enforcement. Both situations require permission to be obtained from the train dispatcher and are accompanied by additional maximum speed restrictions. In addition the ACSES system installed on Acela Express trainsets checks the status of the on-board tilting mechanism and if the tilt is not functioning will revert to a lower set of track speeds. At interlockings where the Data Radio (BCM) is either not installed or not functioning, the train will determine if a positive stop is necessary via the cab signaling system. If it is necessary to pass a signal at Stop after receiving authorization from the dispatcher, ACSES will limit the train to 15 mph within the interlocking limits after use of the Stop Release button.