A rail yard management system for managing railcars having a railcar-based mesh network overlaid thereon, wherein said railcar-based mesh network comprises a communication management unit mounted on a railcar, and train consists comprising a locomotive and one or more railcars and having a train-based mesh network overlaid thereon, wherein said train-based mesh network comprises a powered wireless gateway and said one or more of said communication management units in a mesh network configuration, the system comprising: a rail yard-based mesh network having one or more powered wireless gateways deployed in said rail yard as nodes; and said system configured for performing the functions of: (a) logically assembling train consists; (b) validating assembled train consists; and (c) logically disassembling train consists, wherein said function of logically disassembling said train consist comprises: (a) commanding the powered wireless gateway of the train-based mesh network to logically disassemble said train consist; and wherein said powered wireless gateway, upon receiving a command to disassemble, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network; or (b) said powered wireless gateway of the train-based mesh network automatically sensing the presence of a rail yard-based mesh network upon entering a rail yard; and wherein said powered wireless gateway, upon sensing said rail yard-based mesh network, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network. a rail yard-based mesh network having one or more powered wireless gateways deployed in said rail yard as nodes; and said system configured for performing the functions of: (a) logically assembling train consists; (b) validating assembled train consists; and (c) logically disassembling train consists, wherein said function of logically disassembling said train consist comprises: (a) commanding the powered wireless gateway of the train-based mesh network to logically disassemble said train consist; and wherein said powered wireless gateway, upon receiving a command to disassemble, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network; or (b) said powered wireless gateway of the train-based mesh network automatically sensing the presence of a rail yard-based mesh network upon entering a rail yard; and wherein said powered wireless gateway, upon sensing said rail yard-based mesh network, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network. (a) logically assembling train consists; (b) validating assembled train consists; and (c) logically disassembling train consists, wherein said function of logically disassembling said train consist comprises: (a) commanding the powered wireless gateway of the train-based mesh network to logically disassemble said train consist; and wherein said powered wireless gateway, upon receiving a command to disassemble, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network; or (b) said powered wireless gateway of the train-based mesh network automatically sensing the presence of a rail yard-based mesh network upon entering a rail yard; and wherein said powered wireless gateway, upon sensing said rail yard-based mesh network, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network. (a) commanding the powered wireless gateway of the train-based mesh network to logically disassemble said train consist; and wherein said powered wireless gateway, upon receiving a command to disassemble, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network; or (b) said powered wireless gateway of the train-based mesh network automatically sensing the presence of a rail yard-based mesh network upon entering a rail yard; and wherein said powered wireless gateway, upon sensing said rail yard-based mesh network, sends a command to each of said communication management units in said train-based mesh network to change from said train-based mesh network to said rail yard-based mesh network.