Trade-offs to consider when designing a transit system

by J. Edward Anderson

This listing can be used, as a check-list, by transit system designers who must consider the many trade-offs that need to be made during the transit system design process. It was developed originally by J. Edward Anderson to guide his design of a Personal Rapid Transit (PRT) system, such as the Skyweb Express system. It can also be used to aid the design of a dualmode system. It has been slightly edited and updated by J. Schneider. Suggestions for improvement are welcome and should be sent to jbsATpeakDOTorg.

Guideway Functionality

• Non-exclusive/Exclusive
• Two-way/One-Way

Guideway Physical Design

• At grade/Underground/Elevated
• Reinforced concrete/Steel
• Relative to vehicle: Wider/Narrower
• Relative to chassis: Wider/Narrower
• Connection to support posts: Simply supported/Clamped
• Joints at posts/Joints away from posts
• Open/Covered
• Steel: Plate construction/Truss construction
• Walkways required everywhere: Yes/No
• Walkways required only at some places: Yes/No
• Access to ground from walkways: Ladder/Rescue bucket/Other

Intersections

• People transfer/Vehicles transfer

Propulsion

• Through wheels/Direct linear
• Internal Combustion/Air/Cable/Electric
• If Electric: Synchronous/Pulsed D.C./Induction
• Fixed frequency/Variable Frequency

Primary Power

• On board/Central station/Wayside

Wheel Track

• Monorail/Duorail
• Non-adjustable/Adjustable
• Joint at guideway joints: Yes/No
• Track heating required?: Yes/No
• Heating only at switches?: Yes/No

Service

• Passengers wait/Vehicles wait
• All stops/Some stops/Non-stop
• Standing sometimes/Standing never
• Group/Private
• Rush period only/Limited hours/All hours

Vehicles

• Several people/Single person
• 100,60,40,20,12/ 8,6,4/ 3
• Operates only on streets/dualmode/captive to guideway
• Hanging/side mounted/bottom mounted
• Standees allowed/All seated
• Long throw distance/short throw distance

Vehicle Suspension

• Air cushion/Maglev/Wheels
• If wheels: Foam filled/Solid steel or organic/Air filled

Switch

• None/Track moves/Part on vehicle moves
• Rotation: Vertical/Transverse/Longitudinal
• Stability/Neutral/Bi-stable
• While in use: Requires support/Self-supporting

Control

• On vehicles/At control center/Distributed
• Synchronous/Quasi-Synchronous/Trans-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

Last modified: November 10, 2005