SkyTran's driverless vehicles are lightweight, aggressively streamlined, and extremely energy-efficient.

Inside the Cabin

Inside, the vehicle is a simple cabin: two seats with seatbelts, and a small computer. Wide windows give a good view of the surrounding city or countryside, and a climate control system maintains a comfortable temperature. Passengers sit in tandem (one behind the other) in comfortably reclined seats.

The reason for the tandem seating is for aerodynamics and efficiency, so the frontal area (and aerodynamic drag) is at a minimum. If the people were seated side-by-side rather than in tandem, the vehicles would be half as efficient. (SkyTran's inventor Doug Malewicki used similar principles in the 1980s to build record-setting high-mileage automobiles, setting a Guiness record for a 155 MPG highway-legal gasoline-powered car in 1981 and a 154 MPG diesel record in 1982.)

The fact that the vehicles are driverless is important because it removes human error. Automatically-driven vehicles can be coordinated in ways that human-driven vehicles could never be. It also, of course, frees passengers from worrying about piloting a moving vehicle.

Empty vehicles are 250 pounds and can carry up to 500 pounds inside, making the maximum weight of a loaded vehicle 750 pounds. The vehicles themselves have very few moving parts – the only major moving part is the vehicle itself (minor parts being the door, climate control, emergency brake, and parking wheels). There are no tires, gears, or any other mechanical parts that will continually wear out or need lubrication. In this way, SkyTran is a pure solid state transportation system. SkyTran's vehicles contain thousands fewer parts than modern gasoline-powered cars (which contain about 14,000 parts).

The Bogie and the Guideway

Above the vehicle's cabin, a strong support column connects to the "bogie" trapped inside the guideway. The bogie is the chassis that supports the vehicle. A train's bogie usually has wheels. SkyTran's bogie houses permanent magnets that interact with the guideway to levitate the vehicle. (This is explained further in the magnetic levitation section.) The bogie also contains parking wheels (used only when the vehicle is traveling below 2 mph) and a mechanical emergency brake. The vehicle is propelled using a linear motor embeded in the guideway, and by electromagnets in the track that push the vehicle's permenant magnets forward.

The vehicles are suspended below the guideway, which allows them to bank naturally around turns. Passengers will feel slightly heavier around turns, but will not be jerked sideways. Natural banking also allows the guideway to be lighter and narrower because it doesn't need extreme stiffness to resist the tilting force of vehicles above it.

Safety is a key feature of the vehicles. Seatbelts in each vehicle prevent injury, but active radar on each vehicle makes sure accidents don't happen in the first place. If the radar does see a problem ahead, it can activate its mechanical brake that works by gripping the inner walls of the guideway. This mechanical brake allows a vehicle to stop much faster than a car can, giving a SkyTran vehicle the ability to avoid any potential crash.

SkyTran cars' emergency mechanical brakes (which are 6x better than optimal car braking on dry pavement, performance that's only increased by SkyTran brakes being inside the guideway, where they are shielded from even the worst weather) can bring the vehicle to a complete, safe stop in 55 feet. (100 MPH is 147 feet per second; so the 1/2-second headway that has been discussed as a final goal in a fully-tested system is 73 feet, minus the car length.) A computer-controlled system needs far less time than a human being to detect an obstacle reliably and start applying the brakes. So even at this spacing, SkyTran vehicles will be able to come to a full stop in less distance than the separation between them.

Today's cars don't begin to achieve this. The commonly-recommended "two-second rule" is just time enough for a human driver to notice the taillights ahead and apply the brakes. It doesn't count the much longer time both vehicles need to actually stop from high speed. SkyTran's safety goals are much more ambitious and reliably attainable.

Initial systems will probably run cars 1-2 seconds apart until the mechanics, electronics and software have been checked out for months or years. (What was arguably the first PRT system in Morgantown, WV system in the 1970's ran empty for months while engineers checked everything exhaustively.) We'd guess that SkyTran vehicles will run slower than 100 MPH and farther apart than a half-second for years, to make absolutely sure that the system is ready for safe, optimal speed performance.

If their plans change during a trip, passengers can change their destination by voice or touchscreen command to the onboard computer, or by calling an operator. An emergency button can also be used to call for assistance or for routing the vehicle straight to the nearest police station or hospital. If grid power fails, vehicles would continue to levitate while slowly losing speed, and eventually settle down onto their parking wheels. Normally a vehicle's momentum alone could carry it to the nearest station. In cases where the station is too far, the guideway's regenerative braking system and local backup power can temporarily power straggling vehicles to a station. If all guideway power backups were to fail, each vehicle has an emergency battery that powers its obstacle-avoidance radar and emergency brakes, and can also power it to reach the next station.