The North American freight railroad industry continuously strives towards improvements in the safety and security of freight transportation. One key effort focuses on the use of Wireless Sensor Networks (WSN) technologies to monitor and report mechanical and electrical component status for each railcar in real-time, as well as the status of the transported goods themselves. This allows real-time monitoring of railcar components such as air pressure, wheel bearing temperature, brake failure, wiring integrity, refrigeration unit failure, boxcar door opening, the detection of radioactive materials, dangerous substance leaks, and much more. The aggregated sensor data is transmitted to the locomotive, dispatch centers or regional offices for early fault detection and accident prevention.
Our previous work  has shown that ZigBee technology based on the IEEE 802.15.4 faces numerous obstacles when applied to freight railcar monitoring. To address these problems our team proposed an alternate approach called Hybrid Technology Networking (HTN), which combines the benefits of ZigBee for low-power short-range communication and WiFi for high-performance long-distance communication between HTN sensor clusters.
In this paper, we present our simulation results using our HTN protocol. We compare and discuss the performance of the ZigBee-only network environment with the proposed HTN and demonstrate the advantages offered by HTN. We also discuss our prototype sensor hardware platform using the HTN protocol and provide an outlook of the future work planned for HTN.