Interior of Interlocking Towers

NW Modeling List nw-modeling-list at
Fri Dec 18 21:17:00 EST 2015


If you can't find something specific to Forest tower (or even if you can, but want to know a LOT more about tower operation in a medium-complexity environment), I highly recommend the book "The Classic Railway Signal Tower - New Haven Railroad S.S.44 / BERK".  

Available on Amazon:

Rather expensive, at $39.95 for a large format paperback, but superb content, and engagingly written.

BERK tower is located in Norwalk, CT, and is within walking distance of Norwalk Station on the Metro North (old NH Shoreline) route between Grand Central Terminal and Hartford, CT.  At least as late as 3 years ago, the tower was open for tours-- but seemed to be on a VERY random schedule, so try an internet search before devoting a long journey to check it out.

The above notwithstanding, you might consider that if your trackplan to be "covered" by your model tower doesn't conform to the trackplan covered by the real tower, you might want to make your model tower consistent with your trackplan instead of the prototype trackplan.  

I'd say the first choice you have to make is whether to model interlocking levers of the "armstrong" (mechanical) type, with all of the actuating pipework, bell-cranks, and small foundations that ran along the track from the tower foundation to the switches, derails, and signals back before pneumatic, electro-pneumatic, or electric mechanisms were installed-- or something more modern that involves just wires to actuators placed trackside, and possibly battery wells positioned trackside.  That choice will inform whether you install a bank of large levers, or an electric track map with panel switches behind your upper floor windows.  But that choice will be driven by what era you are modeling, and whether N&W changed the original mechanical plant to something more modern before or after the era you model.

Generally the railroads installed mechanical interlocking plants with 30% or more spare levers that their original trackplan strictly required, so after you add up the number of switchpoints, derails, and signals that your model trackplan requires, add ~1/3 more levers to your lever bank.

An outstanding source of free digital images of the New Haven Shoreline infrastructure (and many other RR infrastructures) is the Historic American Engineering Record (HAER) collection at the Library of Congress-- with many, many images available on-line.  The photos and digital files are generally outstanding.  If you're interested in exploring the breadth of the HAER photos and documentation of whatever railroads the HAER-brains decided to apply themselves to, browse the "Subjects" categories on the following page: 

For a representative example of the interior of the New Haven's SHELL electro-pneumatic tower (it was converted from mechanical before these images were taken) at New Rochelle, NY, check out:  The narrative description addresses use, history, and technology.  This was a VERY busy place from inception through the introduction of CTC. How cool!  

The HAER also has a written description and photos of the New Haven's Niantic River bridge near East Lyme, CT.  See  Included is a photo of the mechanical interlocking lever set, obviously built for a small interlocking plant that controlled a couple of switches, the swing bridge, and probably 4 signals.  The actual mechanical "computer" for all the armstrong types of interlocking plant was located in the lower floor of the tower, directly below the levers.

A REALLY complex plant (NH RR's New Haven, CT facility):

-Eric Bott

-----Original Message-----
From: NW-Modeling-List [mailto:nw-modeling-list-bounces at] On Behalf Of NW Modeling List
Sent: Friday, December 18, 2015 10:51
To: NW Mailing List; nw-modeling-list at
Subject: Interior of Interlocking Towers

I would like to add a prototype interior to my AMB laser cut model of the Interlocking Tower at Forest, VA. Does anyone know of any available plans, drawings, or photos of the prototype. I did a search of the N&WHS archives and found nothing.

Thanks! Merry Christmas to all.

Kevin Byrd
Chesterfield, VA

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