🚀 go-pugleaf

wrob wrote:
> 
> Hm. They shoulda done it to begin with...
> 
> Here's a possibility to make the Rosslyn tunnel cheaper:
> *no flyover*
> 
> I.e. have the "upper" level switch (in the direction
> of Court House) diverge from the northbound Blue Line
> right before the intersection with the eastbound Orange
> Line, and intersect the latter at a right angle. What makes
> this safe is that the trains are already timed to avoid
> running into each other at the *existing* switch.

You are talking about opening a whole new can of worms with this
scheme. This would require a crossing that would have to be
protected with some kind of at grade crossing interlocking,
this would reduce the through put of the eastbound Orange line
K route and limit the through put from the northbound blue line
C route to westbound Orange line K route. In order to properly
protect the crossing the trains coming north on the Blue line C
would be held short of the points of the diverging switch leading
to the crossing as there would not be enough room between the
fouling point of the diverging switch and the crossing for an
8 car train plus adequate stopping distance. The layout would
knock the through put of all of the lines in all directions out
of balance.

The reason the Rosslyn and Pentagon station were built the way
they are is to allow train traveling in opposite to pass one
another with out one having to stop for the other to clear a
crossing.

To give you an idea of what these junction would look like,
go down to C and J junction north of the Eisnhower Avenue station
one can walk around and under the junction to see what a 3 way
railroad flying junction looks like or better yet go to:
http://terraserver.microsoft.com/image.asp?S=10&T=1&X=1602&Y=21485&Z=18&W=2
Mind you this image is old as the Southern Railway yard is no
longer there making foot access to the area quite easy.

I am not say it could not be done the way you describe, it just
would not be a very efficient way to get trains from one route to
the other. Besides the whole reason for building the system is
to move large numbers of passengers from point A to point B. This
layout at this one location would be one big bottle neck in the
system. Build it right the first time so you do not have to come
back 20 or 40 years later and fix the bottle neck at yet a higher
price.

-- 
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    NT Geek, MCP
   Transit Geek                                 John R Cambron
  Railroad Geek                                North Beach MD USA
 Model Railroader HO N                        cambronj@chesapeake.net
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