PHOTOS: Port Road Trips - SHOCKS Interlocking

Next stop on the Enola Branch is SHOCKS interlocking, named after the nearby Shock Mill Bridge.  SHOCKS is a major junction in the former PRR low grade freight system between the Enola Branch and the Royalton Branch.  Originally built around 1905 as part of the A&S low grade improvements between Parkesburg and Enola Yard, SHOCKS is where freight trains could choose the west shore route to Enola or the East Shore route to Harrisburg on what the PRR called the Columbia Branch.  Before the Main Line as we know it was constructed, the Columbia Branch was originally part of the Philadelphia and Columbia Railroad, that in tern functioned as part of the Main Line of Public Works connecting connected Philadelphia to Pittsburgh.  In the 1995 Conrail Diagram CP-SHOCKS can be seen as one of the more interesting features and by that time served as the only remaining junction between signaled lines on the entire Port Road/Enola Branch north of PERRY.

SHOCKS as it stands today was constructed in 1938 as part of the electrification project and along with towers like THORN and PERRY, it represented the PRR's first big foray into CTC systems, although notably with the Traffic part missing.  SHOCKS was an all relay plant with a US&S 504 code line running a few miles south to COLA tower in Columbia.  Here is a 1960's era interlocking diagram showing lever numbers as part of COLA's area of control in a similar fashion to the THORN machine.

SHOCKS was built as a 2x2 flat junction and crossover so that trains entering on any track could then exit on any track.  There are two crossovers and two single turnouts for the Columbia/Royalton branch. It also featured a connection to the Marietta Industrial Track which used to serve a government defense storage facility.   On Track 2 between SHOCKS and COLA is the only segment of real Rule 261 CTC operation that was part of the COLA "CTC" project.  I don't know the rationale for employing 261 on only one of the two tracks, but the PRR had a habit of using traffic control systems as sparingly as possible.  The 1938 interlocking logic and ,layout was left virtually untouched between when it was built and 2008 when NS finally rolled out the first stage of its Port Road re-signaling project.  I don't know many microprocessor based systems that will be able to last 70 years.

As in the previous segments I will be using a few photos taken by a friend of the blog in 2004 as well as some additional photos which date from 2007, shortly before it was re-signaled.  In the above 2004 view we see the westbound main signals at CP-SHOCKS before it was re-signaled.  In the original scheme the dwarf was labeled 110R and the mast 112R and these labels were still accurate in 1995 according to the Conrail interlocking charts.

In this direction trains run in the Rule 251 ABS fashion with a Restricted speed dwarf for reverse direction movements.  Note the 11kv catenary feeders running between the 138kv transmission lines and 6kvsignal power lines.  These ran from the nearby Rowenna Substation to the various catenary sections. The high signal still features the traditional PRR layout for the lower head that only provided a backing plate for the | position since in the pre-1956 rulebook trains would approach Restricting and Slow Approach at a speed where a backing was not deemed to be necessary.  Ah the PRR, just like that old guy who unscrews the light bulbs he doesn't need. 

Here is the same 112R mast signal with its Darth Vader replacement in 2007.  The full lower head provides for Medium Speed routes onto the Royalton Branch.

The rear view shows how age was catching up with the 70-year-old signal, although it was probably nothing that a good coat of paint could fix.

The 110R dwarf signal had been replaced at some point since World War 2 with a new Safetran  equivalent.   The catenary towers on this part of the line remain standing as one is still used by Amtrak to feed the main line at Royalton. 

The dwarf was being replaced by a new Darth mast.  Although still lacking a full upper head as the re-signaling project was not going to touch the Rule 251 on the upper Enola Branch, it would allow wrong-railing trains to cross over at better than Restricted speed.

 

 The Marietta Industrial Track featured an original 1938 dwarf signal (112RC) on a concrete mounting, which probably is an issue if any part of the cable run develops a problem.  In this pic C&S crews can be seen working at the concrete relay house.

In this 2007 view a bland new 3-lamp dwarf signal stands waiting to go into service.

SHOCKS was a pneumatic interlocking and featured two air plants in a similar layout to STELL.  Here is the east end air plant complete with the interlocking horn on the compressor cabinet.

The 1930's didn't fuck around with flimsy sheet metal relay houses as evidenced with this rather squat concrete model that was poured in place.  Behind in the woods is the CTC code line along with the junction that feeds the SHOCKS relay plant.  While the PRR didn't pay for traffic control it did spend the extra bucks for a lead wrapped telecom style cable bundle.

West side of the SHOCKS relay house showing supplemental cabinets and a battery box.

Here is SHOCKS with the points for the #109 facing point crossover and #107 industrial track switch.  Both of the CP value units powering the US&S model A-5 pneumatic point machines are only labeled with the last digit of their controlling level number.

Careful where you step because CP-SHOCKS was pneumatics galore.  Seen here is the #100 crossover with the east A-5 machine of the #113 crossover.  The facing point crossover was used by eastbound trains to use the 261 signaling on the typically westbound track between here and COLA interlocking.

 In this view of the east end of the interlocking we see the #111 switch to the former northbound track of the Columbia/Royalton branch and the lever #100 facing point crossover seen above.

 Facing the other direction we see the #111 switch facing down the former westbound track of the Columbia/Royalton branch.  Note the chance in grade between the two lines.  In 1957 the Columbia/Royalton branch was single tracked except for a 2 mile controlled siding at its eastern end between SHOCKS and a new interlocking named JEB (more on that to come) with the former westbound track serving as the siding.  In 2007 the 6kv 100hz power supply was still in service and being fed from Safe Harbor.  The signal wires on the right go up the Royalton Branch, the left the Enola. 

Today the #115 switch governs traffic down the single main track of the Royalton Branch, formerly the eastbound track.  Point heaters at this interlocking are of the direct burning propane type using sheet metal covers and with fuel fed from a pair of huge tanks off the RoW in the woods under the rusty pole line.

Rotating 180 degrees we see the west end of the #113 trailing point crossover.  This was primarily used by eastbound Columbia/Royalton branch trains to access the Rule 251 eastbound track on the Enola Branch.

Quick view down the Royalton branch showing the two different grade profiles between the main and siding track as well as differences in rail quality.

Here is a 2004 view of the signals coming off the Columbia/Royalton Branch.  The mast is 116L and the dwarf 112L.  The rust is a bit more prevalent on the siding track this time. 

If you thought something looks out of place you would be correct as the position light mast is not only fitted with an incorrect round lower backing, it also uses the R-R upper head lenses that became standard in the Penn Central / Conrail era.  This is the only signal on the Port Road complex to be so equipped.  Whatever fiddling Conrail did to the 116L also resulted in its being approach lit, a feature not applied to the other signals as the presence of 6kv signal power.   One possibility for the upgrade could have been issues with backlighting.

Between 2004 and 2007 the 112L siding dwarf off the Columbia/Royalton Branch fell into some hard times as indicated by a smashed lens.  Also note how 70 years of ballasting has almost completely buried the little signal.

The replacement color light dwarf is located a car-length or two closer to the fouling point.  Not sure if it will give Medium or Slow speed indications.  Also visible in this photo are some of the old catenary section feeds which are still in place.  Lines from the substation run to motor operated isolation switches and then out to the individual trolley wires via cross spans.

As with the 110R, the 116LC wrong direction dwarf was also getting an upgrade to full mast, but moreover due to the section of 261 it features full upper and lower heads.  Ultimately both tracks between here and COLA would get the 261 upgrade, but even with just track 2 under 261 both eastbound tracks would qualify for full signals.

The last signal to be covered is the 110L for eastbound movements on Enola Branch #1 track.  This was originally a catenary pole mounted high signal with the "economic" style lower head we saw on the 112R mast.  However at some point after 1985 or so this was replaced by a new Safetran style position light unit with two round heads and an inter-head spacing that clearly too short.  It's a shame that this sort of slap-dash signaling has fallen by the wayside in today's new environment of standardization :-(

In this rear view you can see the mounting point for the original lower head (look by the signaling cable) and how it compared to the Conrail solution. This arrangement was in place in 2004 so it is unrelated to the re-signaling project. 

That's pretty much it for switches and signals so lets wrap things up with a few additional infrastructure pieces.  Here is the west end air plant which looks a bit newer than the east end plant.

I mentioned it before, but here is a better view of the PRR CTC pole line, which is one of the only classic railroads I know of to use telecom quality cables as opposed to open wire lines.  This is one of the many small ways where the PRR let its money slow and why the pole lines in the electrified region lasted as long as they did.  BTW note how in the background a tree has fallen on the pole line cables and they have soldiered on as without issue.  Also in the frame is the new commercial utility power source that would replace the 6vk 100 HZ signal power feed.

Here we see the new SHOCKS relay hut with the ATCS antenna ready to go up to make the pole line unnecessary.   Also in frame are the catenary section feed cross spans and the 138kv 25Hz transmission lines.

If NS does anything right, it has maintained the Conrail tradition of bright blue interlocking signs.  Thanks NS, I do appriciate the gesture.

Next time we will either travel east to CP-LAKE or take a side trip to CP-JEB.