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Can small cabs move the large numbers of people who would use general mass transit? |
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Written by Administrator
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Friday, 09 February 2007 |
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Today, automobiles averaging 1.2 people per vehicle carry more than 97 percent of the urban passenger-miles in the United States. Uninterrupted flow is the key to capacity, not vehicle size. As an example, 60-passenger buses coming two minutes apart, a very high flow rate for an American bus system, provide the same number of capacity units per hour as 3-passenger PRT vehicles coming every six seconds. One PRT line can serve more than six times this capacity, more passengers per hour than come into downtown Boston during the morning rush period via a three-lane expressway. The line capacity is high because of automatic control, an in-vehicle switch, and electromagnetic propulsion and braking. Automatic control is safer and more reliable than human drivers, permitting vehicles to be separated by small distances. In-vehicle switches work faster and more reliably than moving-track switches, again permitting vehicles to be closely spaced on the guideway. Linear electromagnetic braking is reliable in wet and icy weather that forces systems using rotary motors and wheel braking to spread vehicles far apart because of skidding concerns in emergency stops.
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