Trade-offs Required in the Design of an Optimum Transit System
by
J.Edward Anderson, CEO and President, TAXI 2000 Corporation
Guideway |
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| Non-exclusive | Exclusive | |
| Two-way | One-way | |
| At-grade | Elevated | Underground |
Intersections |
|
| People transfer | Vehicle transfer, at a "Y" |
Propulsion |
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| Through wheels | Direct linear | ||||
| Internal Combusion | Air | Cable | Electric - synchronous | Electric- pulsed DC | Electric- induction |
| Fixed frequency | Variable frequency | ||||
Primary Electrical Power |
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| On board | At central station | At wayside |
Wheel Track |
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| Monorail | Duorail | ||
| Non-adjustable | Adjustable | ||
| Joint at guideway joints? - Yes | Joint at guideway joints? - No | ||
| Heating required? | Yes | Only at switches | No |
Service |
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| Passenger wait? | Vehicles wait? | |
| Serves all stops | Serves some stops | Non-stop service |
| Standing sometimes | Standing never | |
| Group, 2 or more | Private, 1 person only | |
| Rush hours only | Limited hours | All day, every day (24/7) |
Automation |
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| None | Manual backup | No human drivers |
Vehicles |
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| Carries several people | Carries single person | |
| Standees allowed | All are seated | |
| 100,60,20,40,12 passengers | 8,6,4 passengers | 3 passengers |
| Also operates on streets | Dualmode (steets and guideway) | Captive to guideway |
| Hanging (suspended) | Side-mounted | Bottom mounted (supported) |
| Long throw distance | Short throw distance | |
Switch |
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| No switching possible | Track moves | Part on vehicle moves |
| Rotation aid? | Transverse | Longitudinal |
| Stability: Neutral | Stability: Bistable | |
| While in use: requires support | While in use: self-supporting | |
Suspension |
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| Air cushion | Maglev | Wheels-foam | Wheels - steel | Wheels - air filled |
Guideway |
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| Reinforced concrete | Steel | Composites | ||
| Relative to vehicle - wider | Relative to vehicle - narrower | |||
| Relative to chassis - wider | Relative to chassis - narrower | |||
| Connection to posts - simply supported | Connection to posts - clamped | |||
| Joints at posts | Joints away from posts | |||
| Open | Covered | |||
| Steel? | Plate construction | Steel truss construction | ||
| Walkways required? | Yes | At some places | No | |
Control |
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| On-board vehicles | At central center | Distributed | ||
| Synchronous | Quasi-synchronous | Trans-synchronous | Point-synchronous | Asynchronous |
| Headway law? | Fixed time headway | Fixed spacing | Fixed factor of safety | |
| Single path | Redundant paths | |||
| Analog | Digital | |||
| Sensing of vehicle ahead? | Through track | Line of sight | Combination | |
Note: The number of design combinations listed above is 10,110,857,908,322,304