How does PRT handle crowds? |
| Concern: | PRT will be unable to handle crowd conditions. |
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| Reply: | This concern is often stated as 'How long would PRT take to move 200 people waiting at a transit stop?' It is important to realize that the main reason crowds form at conventional transit stations in the first place is the long length of time (relative to PRT) between mass transit arrivals and departures. In only a few cases, detailed below, do crowds of people suddenly appear at a transit stop. Most of the time, people trickle into the station in ones and twos, where they aggregate while waiting for the transit vehicle. So, if 5 people per minute enter a mass transit station which is operating on 10-minute headways, fifty people will be waiting when the vehicle arrives. If 10 people/minute enter, 100 people will be waiting for the train/bus/light rail.
PRT is less susceptible to this problem since the system will have vehicles constantly arriving and departing the stop, taking people away (ideally) as fast as they show up. So the critical issue isn't really crowds as much as the maximum passenger flow the station can sustain to avoid the formation of a crowd to start with. The ability to size PRT stations to their projected demand allows the stations to accommodate from 300 to about 1500 vehicle per hour, sufficient to comfortably handle the highest flows found in conventional mass transit stations. The exception to the above is large public events. Sporting events, concerts, etc., can and do release large numbers of people at a time. But other characteristics of these events actually improve the performance of PRT systems. Specifically, since most people travel to and from these events with one or more companions the average number of people being carried per PRT vehicle (the load factor), will increase. If load factors for these events increase to 2, then the maximum line capacity increases to 11,520 persons/hour from 8,640 persons/hour. The increased load factor also improves total station throughput from a maximum of about 1500 people/hour to around 2500 people/hour. Additionally, the small size of the PRT system will allow multiple PRT stations to be built near, or into, these large venues. So a stadium could have multiple, large, PRT stations, each serving about 2500 persons/hour. If needed, the system could be designed to allow two guideways to service these large trip generators. Each guideway would allow vehicles to disperse into the general PRT network. |
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