RAILROAD SIGNALS of the U.S.
 

AUXILIARY SIGNAL SUPPORT EQUIPMENT

Towers
Equipment Cabinets
Rod Mechanisms
Junction Boxes
Battery Boxes
Impedance Bonds
Compressor and Air Systems

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This section covers other signal related items such as equipment cabinets, battery boxes, etc., that without them, signals would not be able to function.

At The Top Of The Page: A relay cabinet and battery box along the Baltimore Light Rail R-O-W in Linthicum MD, across the tracks from the B&A Maple Road station.

Towers
They now have their own section, please click here

Relay Boxes / Equipment Cabinets

Equipment cabinets house all of the necessary electrical equipment for a particular installation, whether it be for relays that control the signals, telephone equipment, or radios.  Batteries are generally not kept in these cabinets because of the possibility of fires. 

These structures can be big or small.  They can be mounted on the ground, mounted on a concrete slab, mounted on a wood foundation, mounted to a wall, mounted on a pole, or mounted to some other support structure such as the signal bridge or other convenient structure to save the cost of a separate installation.

Older installations employed housing that were made of steel, with newer ones being made of aluminum because they do not rust or need to be painted.  You could also find wooden and concrete used for the purpose, although today, these are rare sights.

Relay / St Denis MD

This is a new installation where signals did not exist before.  CSX realigned the tracks on the approach to St. Denis coming from the Baltimore side.  This prompted them to install a couple of new signal bridges on either side of the Washington Blvd overpass.  This is the equipment cabinet for the one on the south side.  Pictures taken 082805.  Once the signals here were placed into service, the two old CPL signal bridges on either side of HX tower were taken down.

The cabinet is an 8x10 housing, 103" high in the middle, 97" at the corners, and made completely from aluminum.  The first picture is a 3/4 view from across the tracks, the door on this side is 38" wide by 86" high.  In the 2nd view, the door is 27" wide, by 86" high.  The two shots on the right are of the electrical equipment that connects to the outside AC power, the other box is a junction box up on the signal bridge.

Bailey's Wye, Baltimore MD

A couple of shots of relay cabinets located south of Bailey's wye, for a 3 CPL signal bridge on the mainline between DC and Baltimore.  Judging from the raised mounting, this area might be subject to flooding.  It's curious tho, that these things are located across the street from the signals they control.

Rod Mechanisms

Junction Boxes

Relay / St Denis MD

These junction boxes are part of the installation above for the new set of signals.

Battery Boxes

Battery boxes came about because batteries were, and still are, a hazardous item in terms of the hydrogen they can give off during normal operation.  Hydrogen, as you may know, is a extremely flammable element, as pictures of the Hindenburg back in the 1930's can attest.  Because the smallest spark or bit of static electricity can cause the hydrogen to explode, batteries have always been separated from the apparatus they are used to support.

The charging and discharging cycle causes small amounts of hydrogen to be released from the acid in the batteries.  This is one of the reasons signal maintainers need to check the specific gravity of the batteries.  We used to have to check the same things on the batteries in our cars, although newer batteries seem to require less maintenance of this type.

Mason City IA on the UP

A battery box (and it's signals) providing back-up at the diamond with the Iowa Traction, pix from 2006.

Impedance Bonds

Mason City IA

An older installation on the Iowa Traction, on the eastern side of a diamond with the Union Pacific on the south side of town.  Pictures are from a trip to Minneapolis in 2006.

Compressors and Air Systems

Turnouts, or switches, could be operated by a variety of methods.  They can be manually thrown, or they can be remotely activated thru the use of electricity and/or pneumatics.  When switches are controlled by air, a source of high air pressure is needed.  You still need sort sort of electrical control, but the power requirement is not as great since the power to move the points is supplied by the air pressure.  You only need enough voltage and current to control small air valves.

New 8-31-2005
Last messed with 20 Apr 2012