UniModal
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- For the use of "unimodal" in mathematics and statistics, see Unimodal function
UniModal or SkyTran is a proposal by Douglas Malewicki for a 160km/h (100mph) personal rapid transit system. Each car would be suspended from a magnetically-levitated bogie in an overhead track. The magnetic levitation system would be the passive "Inductrack" system using Halbach arrays, as developed by physicist William Post at Lawrence Livermore Laboratories.
Skytran_Car.jpg
Many PRT systems are just "cars on the elevated tracks" and therefore inherit similar inefficiencies. UniModal is said to be designed to transport people with greater speed, lower cost, and better comfort, safety and convenience than an automobile or bus, or even than most PRT systems.
All PRT systems offer nonstop point-to-point travel without waiting. Unimodal's high speeds are said to increase its convenience and attraction for users. The speed would reduce the greatest wasted value of most transit systems: passenger time.
The high speeds would also permit a Unimodal car to have many trips per hour, increasing utilization of its vehicles and reducing the fleet size needed during rush-hour. The high speeds also could reduce all the costs and space associated with large fleet sizes, including public costs such as parking.
High speeds normally require increased "headway", or stopping distance, which reduces the number of vehicles per hour on a track. On all PRT system, vehicles stop on turn-outs, similar to the way taxis do, rather than remaining on the tracks. Unimodal is said to have design features to minimize the expensive of the extra track for turn-outs.
Unimodal's braking would be against a linear motor attached to a steel rail, permitting fast (6G) emergency stops, which would in turn minimize the distance between cars, and therefore permit more cars to be present on the guideway. Passengers would need a seat-belt.
A Unimodal car could only carry two people. The average trip in the U.S. carries 1.16 people, so the designers claim this is not a problem for most trips. The advantage of such a small car is that it weighs less, and therefore has a smaller, less expensive guideway. Larger groups could travel by other means, which would remain available in society. The inventor claims that providing a free taxi service for larger groups would be cheaper than paying for the guideways for a four person car.
The cars are aerodynamically designed for minimum drag to reduce power use and noise. The cars are light-weight, permitting the guideways (the most expensive part of the system) to be made of light-weight, mass produced modular steel components. The expensive cement work is minimized, present in just the foundations of the poles.
Land-use and right-of-way costs are minimized by mounting tracks on poles. Unimodal's light-weight vehicles and tracks are said to permit smaller, more attractive installations.
Magnetic levitation permits high speed and minimizes maintenance. There are said to be hardly any moving parts in the system and therefore there should be very little wear. The additional benefits should be low friction, low track maintenance, and smooth motion with little track noise.
The promoters refer to the system as "solid state". However, wheels are present for use during starting and stopping, and the doors move.
As in all PRT systems, fare-collection, driving and many maintenance tasks would be automated. Unimodal's design is to use voice recognition for its user interface, rather than fare-cards or touch screens.
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Personal Rapid Transit is the generic term for a family of similar systems.