Support Equipment
for the Baltimore Light Rail System




This page covers stuff related to the power system of the Baltimore light rail system - things such as the substations and power feeds.

Power in General

Power for the Baltimore Light Rail System is a nominal 750VDC - Volts DC, or Direct Current.  I say nominal, because the voltage can swing anywhere from under 700V, to over 1100V, depending on how many trains are in that particular power section, and what each train is doing.

Trains when accelerating use a lot of current.  The substations can supply this power, but they can get help from the trains in the form of regenerated voltage if there is one in that section, and it is braking.

When the trains are braking, the motors act as generators (more correctly, alternators, like in your car), and if the line is receptive, output that generated voltage onto the catenary.  Being receptive means the voltage is lower than higher (around 750-800V).

If we have two trains in a particular power section, and they are both braking at the same time, usually only one of them will output their regenerated power up onto the catenary.  This is because the one will be enough to raise the catenary voltage up towards 900-1000V, possibly even more.   The second car would sense that, and divert it's output into the onboard bleeder resistors mounted on the rooftop.  There is more on this operation in my technical section here.

Two adjacent power sections are insulated from each other by a device called an IJ, and Insulated Joint.  Each IJ has two "fingers" that allow an LRV's pantograph to grab power from each adjoining power section briefly, so that the car is not without power even for an instant.  This also means that the pantograph provides a path for the two power sections to be connected for a brief moment, but given the resistances involved, the voltage drop in one substation should be momentary, and current flow shouldn't be too high for very long.

In case two adjacent power sections need to be more permanently joined, in the event that one has to be out of service for some reason, there is a switch that bridges the two sections at the insulated joint.  The hi-voltage switch is at the top of the pole, while the handle to activate it is below.  Examples of these items are shown in the next three photos: the IJ, the power leads to the switch, and the whole set-up.  Notice here, just north of the Lowe's pocket track, that only one of the wires has an IJ here...


Most of the substations of the Baltimore Light Rail System are of the 1 megawatt variety.

There are three substations that are 2 megawatts: at the North Avenue shops, at the stadiums, and one at the Cromwell shops.  The shops need a 2 megawatt substation to power the cars when they are in the yard during the winter and have their heaters are on.

Hunt Valley - Standard 1 Megawatt

Location: CM MN0/885 - Corner of Pepper Road and Schilling Road

Warren Rd - Standard 1 Megawatt

Every substation has a set of status lights on them that can be plainly seen by a passing operator.
The older stations have two lights on EMT that stand above the housing - they are blue and white.
Newer substations have them mounted on the side, and include an additional yellow annunciator.
I need to go thru my books and look up their meaning.

Beltway/Lutherville - Standard 1 Megawatt

Power Feeds

Hunt Valley - CM MN0/885

Notice that this is an "original" installation (the substation is a dark green), and the feed from the substation comes up inside the pole, instead of using a separate conduit, as they used down in Texas.  Texas here does not refer to the state of Texas - Texas is a community between Timonium and Cockeysville, and the fire station located there across from the Target, is #17 and called the Texas station.

Warren Rd

Texas - CM MN0/730

Here we have the power feed from the substation coming up the pole in a separate conduit, instead of inside the pole, as it does at Hunt Valley.

Cromwell - (CM S2/480)

At Cromwell, there are two substations, one for the station and yard, and one for the line heading north.  There are four power feeds, and IJ's all over the place.


I love trains, and I love signals.  I am not an expert.  My webpages reflect what I find on the topic of the page.  This is something I have fun with while trying to help others.

Please Note:  Since the main focus of my two websites is railroad signals, the railfan guides are oriented towards the signal fan being able to locate them.  For those of you into the modeling aspect of our hobby, my indexa page has a list of almost everything railroad oriented I can think of to provide you with at least a few pictures to help you detail your pike.

If this is a railfan page, every effort has been made to make sure that the information contained on this map and in this railfan guide is correct.  Once in a while, an error may creep in :-)

My philosophy: Pictures and maps are worth a thousand words, especially for railfanning.  Text descriptions only get you so far, especially if you get lost or disoriented.  Take along good maps.... a GPS is OK to get somewhere, but maps are still better if you get lost!  I belong to AAA, which allows you to get local maps for free when you visit the local branches.  ADC puts out a nice series of county maps for the Washington DC area, but their state maps do not have the railroads on them.  If you can find em, I like the National Geographic map book of the U.S..... good, clear, and concise graphics, and they do a really good job of showing you where tourist type attractions are, although they too lack the railroads.  Other notes about specific areas will show up on that page if known.

Aerial shots were taken from either Google or Bing Maps as noted.  Screen captures are made with Snagit, a Techsmith product... a great tool if you have never used it! 

By the way, floobydust is a term I picked up 30-40 years ago from a National Semiconductor data book, and means miscellaneous and/or other stuff.

Pictures and additional information is always needed if anyone feels inclined to take 'em, send 'em, and share 'em, or if you have something to add or correct.... credit is always given!  Please be NICE!!!  Contact info is here

Beware: If used as a source, ANYTHING from Wikipedia must be treated as being possibly inaccurate, wrong, or not true.


NEW SEP15/2020, OCT03/2020
Last Updated: 03 October 2020