Unfortunately I didn't get much if any actual train action until I hit Cumberland so anyone who tunes in for trains instead of signals and scenery do not have to read more. For those of you who are still interested my road trip included stops at the very popular Magnolia CPLs, the Paw Paw CPLs, Green Spring interlocking, the abandoned tower at Patterson Creek and finally the railfan bridge at Mexico. The first two locations are situated on the Baltimore and Ohio Railroad's Magnolia Cutoff which was built around 1914 and literally cut off several miles of curvy Main Line track that followed some twisty bends in the Potomac River.
Blah blah blah you can see the full set of photos here.
We begin with the CPLs at MAGNOLIA which are located just east of the Bridge-Tunnel-Bridge complex where the Potomac takes a sharp dip the the south forcing the B&O Main Line to cross into Maryland for the duration of the 1600 foot Graham Tunnel. While the day wasn't too hot, it was still the height of summer and the sun was nearly straight overhead. The intense light, heat and humidity not only made the photos somewhat bright and washed out, they also were affecting the quantum structure of matter causing it to distort in the same way one sees with gravitational anomalies in Star Trek.
You can see the effect here in this telephoto shot of the Graham Tunnel across the first Potomac River bridge. It is hard to emphasize how huge that tunnel is although it is still not able to accommodate double stacks due to the arched roof profile.
In the heyday of the B&O both the cutoff and the old alignment were in use and the line had three or four tracks between West Cumbo interlocking near Martinsburg and Mexico interlocking at the eastern end of Cumberland Yard. On either side of the cutoff signaling was mounted on bridges that spanned all the tracks. On the Magnolia Cutoff, which was built as a 2 track RoW, signaling came to be mounted on bi-directional bracket masts, of which a pair was installed at Magnolia. The eponymous Magnolia CPLs are a bit less impressive when you meet them in person as opposed to how they appear on Wikipedia due to the fact that they are approach lit and in this sort of sunlight tend to blend into the background.
Up close the brackets are clearly in need of buckets and buckets of Rustoleum and it was no big surprise when photos appeared last month of new CPL masts getting ready to replace the westbound bracket. It is for these reasons that it is so important to document this classic infrastructure before it is gone forever.
Even tho the Cuttoff and its CPLs are configured for bi-directional CTC, the ultimate fate of these signals will be sealed by the pole line that still transmits signal state and electrical power. Old school pole lines are a big ticket maintenance item that also have serious reliability ramifications as well. The current state of the art in signal power and communications is to transmit block state through coded track circuits in the rails and deliver electric power either through a utility grid connection or via solar panels and batteries. The old state of the art was a classic multi armed telegraph pole carrying a multitude of single strand copper wire.
These copper wires would transmit single bit state information between the signaling locations such as if the local signal was at Stop and Proceed it would cut voltage to the state wire to the next signaling location triggering an Approach indication. Also included would be some sort of code line to transmit information to any interlockings via pulse code modulation as well as a 400-480v AC power line that would be appropriately rectified at the signal sites to light the signals and power the relays and track circuits.
Here we see the eastbound Magnolia bracket with its wrist thick umbilical of copper signal wires stretching from the telegraph pole to the relay boxes. The box hanging below the crossarm is most likely a power transformer changing the 440V power feed to a lower voltage for consumption by the equipment in the relay box. You can see the difference in the insulators between the ones for signal state and the ones for power supply.
Looking west along the pole line we can see how only a small number of wires are needed for a modern two-track CTC setup. Back in the day before modern communications this pole would have been crammed full of telephone wires connecting not only lineside booths, but also railroad towers and offices stretching hundreds of miles in either direction. Keep in mind that before such things as the power grid and public switched telephone network existed the railroads had to roll their own.
Here we can see the top of the westbound bracket. The sheer quantity of rust is one indication as to why this unit may be marked for replacement.
Here we see the eastbound bracket from the rear showing the pole line and its subsequent journey up and over the mountain that the Graham tunnel bores through. Is it any wonder that pole lines are near the top of a C&S department's capitol improvement list?
Magnolia is also the site of a pole line utility power feed. The power for the pole line's 440v single phase supply has to come from somewhere and this is one of those places. The power comes from a utility pole, through a meter, through some sort of converter box that probably changes the frequency to 100hz or something and then onto the pole line's feeders.
Moving on to the next location we find the CPL bracket mast at PAW PAW. Unlike Magnolia, this signal governs eastbound trains only as the Carothers Tunnel and a curve blocks the sight lines in the westbound direction.
