Personal Trains – research into alternative modes of transporting people
Will robotic SUVs on rails cure those traffic jam blues?
The maze of cobalt-blue steel rails, which extends across a parking lot and into the surrounding woods at a Raytheon test site in Marlborough, Massachusetts, looks like a roller coaster for the faint of heart. Three rubber-tired vehicles with room for four passengers each move quietly along a 2,000-foot-long circuit of elevated tracks. There are no thrilling drops, crazy loops, or screaming joyriders. But as the vehicles change tracks independently in response to commands from a remote computer, visitors get a glimpse of a revolutionary means of transportation that Raytheon engineers hope will entice twenty-first-century suburb-dwellers to leave their cars at home: personal rapid transit.
The typical American suburbanite these days would be helpless without an automobile. With rare exceptions, even folks who commute to work by train or bus tend to drive everywhere else. Since 1950, the percentage of Americans living in suburbs has more than doubled, from 23 to 50 percent. And in the last three decades the number of cars and trucks on the road has grown six times faster than the human population. That means suburbanites are spending a lot of precious time stuck in traffic jams, and not just during rush hours. Also, the nearly one-third of all Americans who can’t drive because of age or disability intensifies the need for public transportation. Their ranks will swell as the baby-boom generation grows old and gray. A few years down the road, public transportation now an anomaly in the suburbs–will become a necessity. The good news: Prototypes are in the works for systems that could make it a lot easier for busy suburbanites to get where they want, when they want, with few hassles.
The concept behind the Raytheon PRT 2000 system marks a radical break with conventional notions of mass transit. Small rail stations would be spaced about a third of a mile apart, a short walk from any point in the network. An escalator would whisk the rider up to the elevated platform, where a vending machine would sell tickets to specific destinations. If a vehicle isn’t already waiting at the station, a central computer would dispatch a single car to pick up the passenger and as many as three companions. Once loaded, the car would zip along above traffic on a six-foot-wide guideway running 16 feet above the street, directly to the station the rider had requested.
The system would be the next best thing to robot-driven taxis. A passenger would not have to follow fixed schedules or ride with strangers. “And unlike linear systems, it requires no transfers,” says Raytheon engineer Steven Gluck. “Any car can take you anywhere within the system.”
Advanced computerized dispatching is the hallmark of the PRT 2000. In the 1980s, Miami and Detroit built so-called “peoplemovers,” which feature driverless rail cars that carry a few dozen passengers at a time along elevated tracks. But the cars are programmed to stop at every station, regardless of whether there’s anyone to pick up or drop off. This slows them to a crawl: cars in the Detroit system average a mere 12 miles an hour. By contrast, PRT 2000 dispatch computers; would calculate the route an individual car should take and relay that information instantaneously to the car. Meanwhile, the processor in the car would monitor the distance from any car ahead. Unlike peoplemover systems, the Raytheon model has stations set up as sidings off the main track, so when one car stops to let off passengers, others can zip past. And because the system is a network of linked loops, it would be easy to expand by simply adding more loops.
Raytheon and the Northeastern Illinois Regional Transportation Authority have already spent more than $50 million to test PRT 2000 and, if additional funding is approved, the first operational system could be erected three years from now in Rosemont, a suburb of Chicago. The three-mile network will connect several hotels with a convention center and a rail station, vaulting passengers over expressways and acres of bleak asphalt.
Personal rapid transit is designed for short-hop trips in the suburbs, but longer journeys pose different problems. As new houses–and new workplaces–are built farther and farther from the centers of large cities, the automobile commute has become increasingly difficult. Commuter buses and light rail are often painfully slow and inconvenient. Last year Congress allocated $30 million to the Federal Transit Authority (FTA) for feasibility studies of a new rail system that could whisk passengers between far-flung suburbs or the outer suburban fringe to the heart of a city in minutes. Magnetically levitated vehicles, fondly known to their boosters as maglevs, would travel either along aboveground tracks or through underground tunnels at astonishing velocities. Maglevs tested in Germany and Japan have been clocked at speeds exceeding 300 miles per hour.
Until now, the biggest obstacle to maglevs has been cost. German and Japanese prototypes use superconducting electromagnets that operate at subfreezing temperatures, entailing enormous refrigeration expenses. “The cost of light rail is $15 million a mile,” says FTA engineer Edward Thomas. “If maglev is $145 million a mile, it’s out of our reach. But if we can get the cost of maglev systems down to, say, $20 million a mile, and it outperforms light rail, then it could be cost-effective.”
Inductrack, a new maglev system developed by the Lawrence Livermore National Laboratory, could be the answer. Inductrack relies on a set of conventional magnets mounted on the underside of a train and arranged in such a way that most of the magnetic force is placed on one side. That effectively doubles the power of the magnets. Small closed coils of insulated wire are embedded under the track to provide levitation. As the magnets pass over the tracks, their field induces an oppositely aligned field in the coils. The two fields then repel, pushing the train off the ground, while a separate set of magnets accelerates and decelerates the train.
Tests last year on small Inductrack carts showed promise, although the train is unlikely to approach speeds of 300 miles per hour. But speeds of just 80 miles per hour would result in quick and cost-effective suburb-to-suburb public transportation.
Another idea that has yet to reach the prototype stage would give suburbanites even more travel options than personal rapid transit or maglevs. Palle Jensen, a Danish inventor, hopes to combine the flexibility of the automobile with the high capacity, efficiency, and safety of rail in a system he calls Rapid Urban Flexible transportation. Jensen envisions a fleet of small electric cars that can operate in ordinary traffic as well as in linked trains on elevated monorails. The cars would ride astride beams, drawing electricity and central control from them. Because the longest part of any journey would be on the beam, the system extends the effective range for electric vehicles. Passengers would be spared the aggravation and safety hazards of highway traffic for most of their trip.
With elevated rail tracks criss-crossing the landscape, the suburbs of the furore may begin to resemble something out of an episode of Flash Gordon–Peril from the Planet Mongo. But the alternative is unthinkable: driving in bumper-to-bumper traffic, amidst a cacophonous symphony of car horns, just to get to the nearest grocery store or shopping mall. Even Gordon’s arch nemesis, Ming the Merciless, would be hard-pressed to come up with a more excruciating torture.
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