Overcoming what it says is a key obstacle to getting Internet access into public transit, Wi-Fi Rail today revealed that it has finished installing and deploying one of the first truly functional underground Wi-Fi systems for trains. In testing since the summer, a system deployed at four stops along the BART (Bay Area Rapid Transit) network in San Francisco has been providing 802.11g wireless access in between the stations regardless of the station or the trains' moving speed. A combination of strategically placed transmitters, amplifiers, and receivers (including some inside the rail cars) keeps the signal strong even along bends in the track; it also provides enough overlap that the connection remains uninterrupted even at 65 miles an hour, Wi-Fi Rail says.

The network also uses single-mode fiber connections to the main network at multiple points in the tunnels, promising a fast connection to the Internet regardless of the number of people on the network. Average speeds are said to top 15 megabits per second and are stable enough that several live video streams and downloads can run uninterrupted, even as a given rail car switches between hotspots.

Wi-Fi Rail has not said if or when it expects a fully commercialized launch of the network across BART beyond the beta test area or in other cities but expects to see the technology deployed in other cities and services in the near future.