> Personal Rapid Transit


>David H. Walworth has been involved with Personal Rapid Transit (PRT)

>since he was introduced to the concept more than 30 years ago by John

>Lambert, cofounder with Al Spivak of the Modern Transit Society.


>Dave will present the concept of PRT, a system of fixed guideways

>spaced at 1/2 mile intervals using three passenger vehicles that

>automatically take you to your requested destination. Dave will

>elaborate on the details of such a system, describe real-world

>examples, and explain why we don't have it now and when we'll be

>likely to get it.

The idea behind PRT is that you can have some small cars ready to go at any time at every station. This makes it possible for people to buy their tickets, hop in and take off. Because the destination is programmed in at the beginning, it does not stop at places between the originating point and final destination, saving much time for all passengers.

The small size of the individual vehicles means there are many savings compared to normal rail systems. The right of way required is narrow compared to what a train or auto requires. Because the vehicles are relatively light, bridges and track can be built for much less than a full scale train system would cost. Dave showed pictures of a PRT system that was installed in a city in Germany on a trial basis for a few years in the '70's, and it did look light and modern.

The rail works as a guideways for the wheels of the car, which are there just to give it low rolling resistance. Power is provided by using the track as the stator of a linear induction motor, with power provided by electric wiring of the rail. Braking is done by reversing power to the system that works as a motor. Built into every car is the ability to steer at forks in the track. This is necessary because it takes too long to reset rail switches between cars for that to be practical.

The station is small compared to a normal train station, basically just a rail siding where about half a dozen vehicles can park, with on and off ramps just long enough to allow the vehicles to attain speed or stop. The idea is to sprinkle them liberally through the system, so that the consumer does not have to go far to get to one.

Peak capacity of the system is one vehicle every 2.6 seconds, meaning that about 1400 could pass each station in an hour on each rail. Theoretically, the system could run with very little movement of empty cars, making it very efficient.

Tian Harter