Onboard Wi-Fi for a new 95-mile rail system in New Mexico relies on WiMax for backhaul: The folks at Azulstar, working with INX, built out the service, which will be free to passengers, and available along the route and at 15 train stations. Having driven some of that route (Albuquerque to Santa Fe), I reckon that the flatness of the terrain coupled with some mesas and higher points made the install feasible with just 22 base stations.
Azulstar, which I wrote about two years ago for its plan to use a special shared, cheap licensed band to run WiMax services, says it gets 6 Mbps downstream and 4 Mbps upstream.
The company's head, Tyler van Houwelingen, told me via email that the system is redundant and mostly wireless. 5 GHz and 18 GHz are used for backhaul combined with some wired connections along the route, and WiMax at 3.65 GHz (that special band) is used with a 900 MHz fallback. Base stations are powered by solar and electrical with a 24-hour battery backup. Given winter and summer conditions in New Mexico, redundancy won't be extraneous.