CPL, or Color Position Light signals were exclusive to the Baltimore and Ohio Railroad, and it's affiliates.  You could find them anywhere the B&O went.   However, now that all of the former B&O lines are part of CSX, they have been accelerating their efforts to replace the CPL's with modern 3 color light signals everywhere (yuk).

Other railroads using CPL's are the Staten Island Rapid Transit (SIRT)(now part of the MTA), the former B&O Chicago Terminal, and the former Alton and Southern.  Dwarf CPL's were also chosen to be used in and out of Union Station in Washington DC, although they appeared on signal and cantilever bridges above the tracks.

CPL dwarf signals also enjoy being the only dwarfs which, if so outfitted, can display ALL of the aspects of a high signal.  The only one I ever saw so configured was at the B&O Railroad Museum in Baltimore.  However, I don't know if the signal before it came to the museum was originally in this form, or if it was put together just for display.  Since the snow cave-in of 2003, the signal has not been on display because the museum has decided not to use the outside wall for displaying much of anything.

   Michael Watnoski's primer on CPL signals 

The Signal

The main CPL signal "head" consists of a number of individual lamp assemblies mounted to a circular background 3ft-4" in diameter.  The background is mounted to the mast with two heavy duty steel straps and U-bolts.  Mounted to the backside of the background is a junction box, where the cables from the relay cabinet terminate, and individual wires go out to the lamp assemblies.  A fully populated CPL head would contain eight (8) lamp assemblies, two lamps for each aspect.  As with the Pennsy Position Light signals, the B&O Color Position Light signals were an attempt by the designer to simulate the position capability of the semaphore signal.  On some older installations, the transformers (one was needed for each circuit that had to be illuminated) to step down the 120VAC were installed in the junction box, but because of the "high-voltage" in there mixed with low voltage, and the safety hazard it presented, I guess they eventually decided to remove them... cost to provide a separate transformer for each circuit may have also been a factor.

A CPL signal also had what are known as marker lamps located above and below the main signal head.  Very few CPL signals consisted just of a main signal head, most had at least one marker lamp.  If it was a high signal, the sole white marker lamp was usually directly above, so the signal could display a clear aspect.  Without the marker lamp, the green indication was slow-approach slow.  A CPL signal could contain as many as six (6) marker lamps, and the only one we are familiar with used to be in Deschler OH, but has been replaced with color light signals by CSX.  An almost full CPL signal still exists in Baltimore, with the only aspect missing is restricting on the main head.


  CPL pages from a 1935 US&S catalog.



A single aspect/restrict only CPL adjacent to the Westport Light Rail station in south Baltimore.



          The signal head & approach sign.



 The 3 signals below and Bailey's Wye are shown on this B&O map of the central Baltimore MD area.

An almost full CPL
The right signal has all 6 markers... the only aspect it is missing is restricting.



 This GE just passed the restrict only signal above, about a half mile ago.
Located in south Baltimore along the mainline to DC at "Carrolls" - can be seen from NB I95 - Pix from 28AUG2005

A 3 CPL signal bridge - located just south of Baileys Wye in south Baltimore

Signal head close-ups.
These heads are the same as the one I have in my backyard.  These things are built to last, as the background is 1/8" thick.  Notice that they are mounted on a slight angle, for the approach to the bridge is on a curve.

Marker lamp close-ups.

         Signal bridge details.


This signal is located just south of Camden and Bailey's Wye - It's for northbound traffic.

For the time being, these CPL's, and others on the south side of the Howard St tunnel have escaped the "Darth Vader" signal upgrade project.  It's not known how much longer these will be around, so if you like 'em, go out and get your pix now!

It appears (so far) that most of the signals on the mainline between Baltimore and DC are intact, however, two new signal bridges went up in St. Denis/Relay last year, and the signals were cut over towards the end of 2007.  CSX was very quick in taking down the two old B&O signals bridges on either side of HX tower.






A CPL signal with 5 markers - for NB reverse traffic on the main line to DC in south Baltimore - 28AUG2005









A couple of old CPL's placed on a new cantilever bridge, just north of the signal above.

  Two aspect CPL by Washington Blvd and Monroe St, in south Baltimore


This signal is located just off the Baltimore-Washington DC main line at Carrolls, it sits across from the old Montgomery Wards warehouse at Monroe and Washington Blvd.  There was once two tracks thru here, and each track had a high signal for the main traffic direction and a dwarf CPL for reverse traffic.  When they took out the second track, the CPL's went with it.

This signal is unique in Baltimore, in that it has a pole mounted switch to cancel the crossing gates in the event the train was going to sit at the crossing for any amount of time.  There are two other switches at this location, however, this is the only one mounted on a signal pole.  Pix from 11MAR2006.

  Map of the Bailey's Wye area

For a more detailed map of the Baileys Wye area, click HERE.


   CPL on the SW leg of Bailey's Wye in dntn Baltimore, for freights coming out of Riverside Yard.

     A couple of shots of signals on the south side of the Harpers Ferry tunnel.


CPL's a plenty at the west (south) end of Mt. Winans yard in south Baltimore MD, with an approaching westbound CSX freight, taken around 1995. 

Most of these signals were replaced by "Darth Vader" color light signals in 2007.  CPL's around the curve in Landsdowne were replaced a year or so earlier.  The freight is getting ready to cross Gable Ave, a fairly good photo spot off of Washington Blvd, near Patapsco (I wouldn't venture into the yard, tho).  This freight might have come from Curtiss Bay if it took the crossover just off the right side of the pix, if not, it took the long way around coming from Baltimore going thru Mt. Clare yard A.  For a B&O map of the area, click HERE (same as the map above).  The map is dated 1988, but does not have the signal bridge by Ridgely St on it.  Curious.  There is a little arrow on the map along Patapsco Ave that shows where the picture was taken from.  The map covers from Lansdowne Rd on the south side to Camden Station (before it's current 2 track configuration). 





This picture was taken from Gable Avenue, looking towards the place I took the above picture from. 





At the bottom, you can see a CPL dwarf.  At the top of the photo, and the two bright dots in the middle, are high CPL's.  The two large white dots are streetlamps on the bridge that I took the other photo from, and finally, the cluster of three lights is a freight waiting to go into Curtis Bay, sitting under the bridge.

New 10-6-2006
Last Modified: 04-Dec-2008