Amtrak's Acela Express trains run along the Washington-Boston-New York corridor and offer two things not often seen by US rail passengers: decent speeds and free WiFi. One of those benefits could soon come to every Amtrak train nationwide. Guess which one?

Onboard WiFi has been a huge hit on the Acela trains. Amtrak announced last week that 39 percent of all Acela riders had logged onto the Internet aboard the train and that the service had given Amtrak a major competitive advantage over bus and air travel in the Northeast corridor.

Now, Amtrak wants to expand the bandwidth available to the system and hopes to extend WiFi service to its nationwide fleet. A request for proposals has just gone out to vendors, and installation should begin this autumn.

The Acela trains proved relatively easy to wire, for two reasons. First, cell phone towers in the densely populated Northeast corridor can provide a steady connection that (as I can tell you from experience) does not exist when blasting through rural New Mexico.

Second, the trains have a fixed set of cars. On other routes, Amtrak mixes car types together in different configurations, switches some between trains en route, and splits trains. Any WiFi system for such trains needs to handle this sort of shuffling without problems.

At a major rail convention in Europe this week, Amtrak talked up the success of its system and provided some details on the current Acela implementation. MuniWireless, which was at the event, provides the details:

Each train has a central system housed in a ‘brain car’ comprising up to eight data modems using all four major US cellular carriers; Verizon, AT&T, Sprint and T-Mobile. A 5GHz wireless network connects the brain car to the rest of the train, providing speeds of 12-22Mbps between carriages with approximately 3.5Mbps total bandwidth available for passenger Wi-Fi connections to the Internet. The bottleneck in any train-bound system will always be the backhaul, so AmtrakConnect uses a quality-of-service system that segregates passenger traffic from on-board system traffic, and uses content filtering to manage bandwidth on a per user basis and block certain material including streaming video. The on-train system is augmented by multi-megabit trackside and in-station wireless broadband that offloads traffic from the cellular connections to platform-based infrastructure when a train is at the station.

WiFi looks inescapable. Like Amtrak, airlines now commonly offer the technology in-flight, and it's starting to make its way into cars and portable 3G/4G WiFi hotspots. All the data usage is good news for cell providers, who provide most of these data connections—assuming that they can handle all the traffic.