From: brennan@cunixf.cc.columbia.edu (Joseph Brennan)
Subject: Re: scanner and train questions
Reply-To: brennan@cunixf.cc.columbia.edu (Joseph Brennan)
Organization: Columbia University
Date: Fri, 31 Jul 1992 17:53:39 GMT

In article <1992Jul31.134137.5114@das.harvard.edu> neal@endor.uucp
(Lisa Neal) [or Jonathan Neal] writes:

>*      Why are there no double deck Amtrak trains in the eastern part of
>the U.S.?  I have heard only two theories about this:  1) The east coast
>lines have low tunnels and underpasses that would be impossible for
>double deck trains to fit through

That's the reason.  Someone has pointed out correctly that tall
freight cars get to the east, but they can only travel on certain
routes.  Some of the main passenger tracks have restrictions, among
them numerous points under the Northeast Corridor's 11kv electric
wires.  For example, the wire barely clears normal-height trains
through the Penn Station tunnels at New York.  Penn is probably the
"ruling height", that is, other structures are allowed to be that low
since trains would have to be low enough to pass Penn Station anyway.
Historically, the Pennsylvania Railroad had run-through passenger cars
with so many other eastern roads that they all adopted that height as
the maximum for passenger cars too (PRR wasn't called "The Standard
Railroad of the World" for nothing).

>*      When I was passing through the Albany station several weeks ago,
>I saw the Turboliner fleet maintenence station.  I was impressed, but a
>fellow passenger told me they were just cosmetically different from the
>other Amtrak trains.  Can it really achieve "turbo" speeds, or is it
>just a sleeker, more modern-looking train with no different performance?

It's mechanically different.  The word "turbo" somehow conveys the
notion of great speed, but in that sense they're merely as fast as
anything else Amtrak would run there.

>*      How is the position of railroad switches changed? Do people have
>to go out and switch them by hand, or are they thrown electrically from
>a central dispatch station?

Switches on mainlines that are regularly moved in the course of a day
are usually remotely controlled.  The oldest system was mechanical--
ever see a picture of a towerman using all his weight on a huge lever
coming up from the floor-- it pulled a bar that pulled a bar... that
moved the switch.  The next step, 1890's I think, was to run pipes to
the switch and use pneumatic pressure to move the switch; the pump is
often located near the switch.  There are still some pneumatic
switches in the New York subway and you can hear the pumps chugging
away periodically to keep pressure in the line.  Not much later they
began to use small electric motors to move the switch.  In the 1950's
(?) they began to centralize control to fewer sites, using electronics
for the first time.  

A very important part about all these systems, even the mechanical
ones, is that the switches and signals in an area are interlocked, and
the controls are called an interlocking for that reason.  As a simple
example, you have to set the signals (both directions) to red before
the system will let you move the switch.  This can get fiercely
complicated where there are multiple switches and crossovers.  The
most modern ones are computerized, so the system itself can, using the
same example, set signals to red and then move the switch, at one
command.

Switches that aren't used so often, or on branch lines, are, on the
other hand, usually hand-thrown on site.  A tool is used, a long
lever, so the crewperson can use body weight to move it.  Crews on
local freights normally move many switches per day this way.

>*      How does the dispatch station know where the trains are? Is it
>just by the engineer notifying them, or is it done by some computerized
>system in the track?

Where the dispatching is centralized, some sort of electronic system
is used so the staff can see where the trains are.  Typically it's a
large diagram of the tracks with lights showing where trains are.
They might still need radio to identify what train it is.  This system
began in the 1950's I think.  At the older type of installation, the
interlockings had to be in sight of the switches so the crew could
eyeball what train was coming.

--Joe Brennan

Newsgroups: rec.railroad