by Bob Fleming
About the Seattle Center Monorail
Seattle Center Monorail web site
Advantages of monorail
My opinions about Seattle area monorail
Former Seattle Monorail Project
A Proposed Regional Monorail System
Arguments against monorail and my responses
My ideas for monorail system design
My ideas for routes
(PRT) Personal Rapid Transit
Frequently asked questions
Links to other monorail sites
Other Sites of MineA Greater Seattle My mobility web site My transportation web site My mass transit web site The Fleming Family home page Bob Fleming’s home page
The original design for the Green Line was for the entire line to consist of two guideways (beams) for the trains to run on, with trains going in one direction using one guideway and trains going the opposite direction using the other guideway.
Toward the end of the project, in order to cut costs, the SMP was proposing to use a single guideway in places in order to cut costs and to reduce visual impact on the neighborhood. Switches at each end of a single-tracked section of the line, along with computer controls, would switch only one train at a time onto the single guideway and prevent trains going opposite directions from colliding.
Cost savings would not only be from having one less guideway to pay for. A single guideway would also permit less complex and lighter-duty pylons (supporting columns) and less expensive foundations.
I think that the plan would work, however I am opposed to the single-tracking concept for two basic reasons — safety and future planning.
The safety issue is simple. Anytime you have the possibility of two trains running in opposite directions on the same track (or guideway in this case) there is a risk of a catastrophic collision. This system would have used the most modern and sophisticated compouter system that should eliminate any chance whatsoever of two trains from opposite directions from getting switched onto the same same guideway. There would be very thorough testing of the system before it goes into service. I really doubt there would ever be a collision. But computers can fail and people can make mistakes. Even though the risk of an accident would be extremely small, the result of two trains colliding head-on at a high speed would be so devastating, with potential loss of hundreds of lives, that I don’t think we should take the risk, no matter how slight.
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©2002 Robert M. Fleming Jr.
This page was last updated on 9 May 2016