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Friday, July 9, 2021

Searchlight News

 I just realized that I had a growing backlog of news items regarding searchlight signals, some of it a little bit old, but still worth highlighting. First up the TWC/ABS territory on the end of Harvard Sub north of Harvard, WI is being replaced by CTC taking the CNW searchlight signals with them.  Although not part of the METRA territory, UP appears inclined to simplify dispatching on the part of the line that probably sees only 2-4 trains per day. This is the most up to date news so anyone in the area can probably still document the old signals.

Next, the former ATSF diamond in Plainview, TX is also losing its searchlights as of November, 2020, so they might alread be gone. 

Next, with the CNW ATC out of service, UP appears to feel free to now alter the interlockings on the Geneva Sub (former CNW main line) between West Chicago and Iowa, which had formerly gotten a reprieve. This will see the replacement of the CNW hallmark oval target searchlights.

Finally I have another case of some signals that got away.  In early 2020, the Guilford Rail System retired the signals on the Northern Main Line between Nashua and Manchester, NH due to low traffic and the generally failing state of the system.

While the above diagram doesn't make this abandonment look that bad, there were 6 automatic signal locations and 3 interlockings north of Nashua compared to only 2 automatic locations and 2 interlockings to the south. What's even worse was that I was in the are last Labour Day, however I was fixated on the Lowell terminal area due to the MBTA's Rule 562 project and didn't even realize that the North Main Line was even signaled.  I passed within 1200 feet of the retired CPN-28 without realizing it was there only to find out a few months that the signals had been taken down.  Not sure what the state of the other locations are, removed or just turned, but its probably still worth checking out.

Tuesday, June 29, 2021

The Last Days of COLA Tower

I just stumbled upon a Youtube video from 2015 showing video shot inside COLA tower in Columbia, PA about two months before and then again on the day of its closure on March 15, 1987.  What makes the video amazing is that it can be compared to the interior photos I took in 2020 to see the state the tower was left in and how things changed over the intervening 20 years.

Just to recap COLA was one of a few 1930's PRR electrification associated CTC projects.   The tower was open between 1938 and 1987 and then the original hardware was run via remote control until 2012.  The remote interlockings under COLA's control could have that re-routed to the Conrail dispatch office in Mt. Holly, NJ.  From the video we can see that COLA interlocking itself had a new local control panel placed in the operator's room.  I am unsure when the CTC console was removed, but from the video it appears that it was not going to remain "wired up" and by the end only the western end of the territory (JEB, SHOCKS, Etc) was still active.

Other things that vanished include the defect detector readouts, all manner of random electronics and the 1930's vintage hanging overhead lamp.  What stayed behind?  The chairs and, the vintage Kelvinator refrigerator! It's also hard to tell if the PC green lockers were there in 1987 or brought in later to support a maintainers base. The wall behind the operator's with all the pasted up articles was obscured by a shelving unit with electronics on it, possibly in preparation for the re-signaling. In the Jan 13th video it also appears that the tower was a two person job, although there could be a number of reasons for an extra person to be on hand.

Anyway, despite frequent tower searches, Youtube still has the capacity to surprise.  It was really cool seeing how COLA's sibling tower,THORN, compares with COLA after THORN wound up with Amtrak instead of Conrail.

Saturday, June 26, 2021


The Reading Darby Creek Drawbridge is located on a bit of industrial track that served industry along the Delaware River between Philadelphia and Chester, PA. Directly paralleled by a competing PRR line, much of the Reading branch and along the the Darby Creek bridge, were abandoned shortly after the formation of Conrail in 1976.

Nevertheless, movable bridges are substantial pieces of kit with non-trivial removal costs so for the last 45 years the remains of the Reading Darby Creek Bridge have sat in the weeds next to the PRR bridge, permanently open. 

It's easy to forget that movable bridges are almost all railroad interlockings, even on otherwise un-signaled territory. Moreover, this means that before CTC the person on hand to work the bridge would also need to work an interlocking machine and both Darby Creek bridges operated in this manner with the tender/operator managing both train movements and marine traffic.

In the case pf the Reading bridge, the interlocking was controlled through a US&S Electro-Mechanical machine with 2 active mechanical levers on a 4 lever frame and 5 active crank style levers on a 7 lever electric frame.

The combination of being manned for bridge openings, no need to associate with CTC territory and flying under the radar in remote locations has allowed for movable bridges to survive as active interlocking towers well beyond even their busiest main line peers. While the PRR bridge ultimately had its interlocking and bridge control hardware replaced in 2005, the Reading bridge, in a strange turn of fortune, unwittingly became a time capsule as Conrail literally turned out the lights on the old bridge in 1976 and walked away leaving the old interlocking cabin and interlocking machine mostly intact.

Placed in service some time around 1923, the Union Switch and Signal Electro + Mechanical interlocking machine used a combination of electric Model 14 style crank levers for electric based components such as the signals, and long mechanical "Armstrong" style levers for the mechanical components such as the bridge locks.

The mechanical levers, 5, 9 and 13, had only 5 and 9 functioning when the diagram was drawn in 1955 to operate the mechanical bridge locks with 5 operating the north lock and 9 the south.

As US&S had taken over the Saxby and Farmer style interlocking machine from the UK, this small frame still used the S&F style rocker action to interface the levers with the logic.

The electric portion of the machine has room for 7 crank style levers with 6 levers originally installed ad one of those being a spare. Three downward oriented levers, 4, 8 and 12, operated a total of 5 smashboard signals, while the upward oriented levers confirmed the position of the bridge locks (#6), worked the master bridge unlock (#10) and served as a spare (#2).

The rear of the machine exposes typical US&S style interlocking technology including magnetic coils for the quadrant style lever locks and electric contact spindles to interface the mechanical components with the various electric circuits.

Monday, June 14, 2021

P&LE Tower Update - CP-3Y Demolished

 A couple years ago I posted a piece on how to use Google Street View to check on the status of surviving interlocking towers.  At the time I determined that the former PRR tower BECK and the former P&LE tower CP-3 had both been demolished, while the P&LE tower CP-3Y was still standing. At the time I was using the latest Street View image from July 2016, which showed the existence of CP-3Y.

However what i did not know that was a new set of images from August 2018 were still in the pipeline and would have revealed that CP-3Y had indeed been demolished in the intervening time period. I believe this would eliminate the last standing classic style P&LE interlocking tower.

Just goes to show that time doesn't stand still and just because a tower is here today or on streetview today does not mean it will be there tomorrow so stay alert and remember to check back on a regular basis. 

Sunday, June 6, 2021

PHOTOS: Inside SEPTA's Last Towers

Over the last 20 years North America has seen the virtual extinction of "Paper Dispatching", the practice of railroad dispatchers being totally reliant on field tower operators as their eyes and ears. Operators report movements to dispatchers, dispatchers mark down train progress and inform the operators of any necessary changes. Depending on the railroad the dispatchers and operators may have more or less authority and in others the while two level hierarchy may not exist at all. Anyway, in this time period there has only been one rail system that I am aware of that went from Tower controlled to Dispatcher controlled in one fell swoop and that would be Philadelphia's commuter railroad SEPTA. 

Founded as an umbrella funding organization in the 1960's, for its first decade and a half SEPTA contracted with the legacy carriers Penn Central and Reading and later the government supported Conrail that emerged from the bankruptcies of both predecessors, to provide service on the Pennsylvania and Reading Railroad's vintage electrified suburban districts. The PRR side of the house was generally worked on the interlocking tower system with single towers controlling one or a few adjacent interlockings. The Reading on the other hand developed a taste for CTC schemes controlled by panels within existing towers. In the mid-1980's a series of events would combine to create SEPTA's unique tower culture. First, Conrail was forced to pull out of contract suburban operation in favor of direct operation by SEPTA. Second, SEPTA completed construction of the Center City Commuter Tunnel that linked the PRR and Reading networks, eliminating the stub terminals and third, SEPTA built the brand new Airport Line along with a number of "state of good repair" projects like the rebuilding of the Reading trunk line and improvements to the West Chester and Chestnut Hill West lines.

The result was that all of SEPTA's rails were controlled from 7 interlocking towers. The first two, WIND and WAYNE, were co-located within the old Reading WAYNE tower building at Wayne Jct and consisted of two 1960's vintage CTC panels that not only controlled practically all of the Reading suburban network, but also parts of Conrail freight lines due to the shared Reading System heritage. The next two, BROAD and MARK, were built as part of the Commuter Tunnel Project and replaced two large Model 14 legacy terminal plants with modern N-X panels. The next two, MEDIA and CHESTNUT HILL (WEST), were direct PRR legacy towers that controlled terminal operations on the West Chester and Chestnut Hill West lines with their original interlocking equipment. Finally A TOWER was constructed new in 1985 to control the Airport Line with a contemporary unit level panel.

Beginning our tour at Wayne Junction, WAYNE tower was the most traditional of SEPTA's diverse rail control locations being located inside the former Reading WS tower, a 1920's era Model 14 powered facility that controlled the double junction between the New York/Bethlehem main line, Chestnut Hill East branch and Tabor Branch freight link. Unlike the PRR, the Reading wasn't afraid of new technology and in 1965 it implemented a wide-scale CTC project that consolidated control of its Suburban network inside WS/WAYNE tower. (Note, by CTC I mean remote interlocking control as there was only a limited amount of actual Rule 261/CTC operation in this territory.) In the tower the old Model 14 machine was supplanted by two high end General Railway Signal NX panels installed in adjacent corners of the operator's floor.

Operator lines a route at 16TH ST JCT on the WAYNE panel in 1991.

Other half of the WAYNE panel in 1991.

This gave rise to WAYNE Towers's unique "Two Towers in One" layout with the "WAYNE" panel and operator controlling everything between 16TH ST JUNCTION at the top of the Viaduct to TABOR JCT (Fern Rock) on the Main Line and the Fox Chase branch (via Newtown Jct and Cheltenham Jct). The WAYNE panel saw one major alteration with the "south" end of the panel being extended to accommodate the insertion of the new HUNT interlocking and reconfiguration of WAYNE interlocking to support the mid-80's opening of Robert's Yard. Compare the above and below photos to the original 1965 configuration (NSFW).


South end of the WAYNE panel in 1994

North end of the WAYNE panel in 1994

The second panel and its operator was known as WIND and was interesting for not only being a virtual tower located about 6 feet away from the WAYNE panel, but also not actually controlling an interlocking named WIND. WIND's territory was everything north of Tabor Junction including the R5 route from Jenkintown to Doylestown, the R2 to Warminster, the old New York Branch/R3 to Woodbourne and even the previously signaled Stony Creek Branch to Norristown. WIND also had control of the New York Short Line that would become the Conrail Trenton Line north of Cheltenham Jct which included a single controlled siding and various joint interlockings between Neshaminy Jct and Woodbourne. 

WIND panel 1991 with WOOD interlocking and Fairless Branch.

Between 1991 and 1993 the first state of the Conrail SEPTAration began with a re-signaling and track re-alignment project on the Trenton Line transferring control of Conrail trains between CP-CHELTENHAM JCT and CP-WOOD (exclusive) to the Conrail dispatcher. You can see in the following 1994 photo of WIND how the north end of the old New York Branch has been deleted off the panel as an active element. 

WIND panel in 1994 w/ WOOD interlocking etc blanked out.

SEPTA's WIND would retain control of both CP-WOOD and gain control of CP-TRENT after TRENT tower's closure in 1994. Unfortunately my photos do not reveal the method of control, but it would most likely be a computer terminal seeing as how CP-WOOD and CP-TRENT was re-signaled to 90's Conrail standards. The only remaining portion of the Reading Suburban network I have yet to cover is the Norristown terminal area that was originally controlled from a CTC panel in NORRIS tower. NORRIS tower closed some time after 1988 and by 1994 the CTC panel had appeared in WAYNE tower (likely under purview of the WAYNE operator). A 1991 photo shows a non-operable mimic board installed in the tower which may have operated to inform the WAYNE operator of R6 terminal movements before NORRIS closed. 

1991 Norristown area minic board.


1994 Norristown area CTC panel.

If you were wondering how two operators could handle all the train movements on the Reading side of the SEPTA network on an NX panel without any form of labeling, I was told that at peak times each "tower' each would support at least two panel operators working in a non-socially distanced manner. Based on the recollections of a visitor, was also likely that the physical WAYNE tower operation included a train director to call some routes and handle communications with the SEPTA dispatchers. By the turn of the 21st century SEPTA WIND and WAYNE had a very distinct presence on the scanner scene with their VHF transmissions registering loud and clear at least 10 miles distant in South Jersey. It was a truly modern rail dispatching operation in all but name.

MARK tower panel.

Looping through Center City, the next tower encountered on the SEPTA trunk was MARK. Part of the Market East station complex, I believe it was located somewhere around the ticket counter / station master's office on the east end. MARK arguably replaced the 111 lever Model 14 RACE ST interlocking plant that controlled the Reading Terminal complex. The Center City Commuter Tunnel shows the gross inefficiency of stub terminals as a the 13 track Reading Terminal complex was able to be replaced by 4 through tracks. MARK "tower" consisted of a US&S unit lever panel in an office controlling VINE, a 4-track full crossover hear the north end of the tunnel, and MARK, an interlocking without any appliances (aka switches, derails, etc) that spanned the length of the Market East station platforms. It did not control the adjacent JUNIPER interlocking located between Market East and Suburban station on tracks 2 and 3. MARK opened in 1984 with the closure of Reading Terminal.

BROAD tower center panel with 20TH ST and SCHUYLKILL interlockings.

Friday, May 28, 2021

10 Years of The Position Light - A Milepost

Not sure anybody noticed, but May 28th marks a decade since I started this blog as a place to archive long form signaling related content I had previously published on old school web forums with limited visibility. Due to an odd coincidence at the beginning, I have accidentally committed myself to and then maintained a 49 post per year schedule with signaling news, history and general overviews of some of the more obscure topics such as interlocking horns. Over the past decade there was been way more bad news than good and I can't say that things stand to improve in that regard, but it has still been my privilege to mark the passage of so many pieces of both railroad and technological history. If one was to ask what I was most proud of it would likely be the comprehensive surveys of PRR Main Line and Port Road signaling along with the documentation of the late great METRA interlocking tower interiors.

I'm sure a lot of people out there would use this sort of milestone to pivot to some completely new/different project like elevators or some sort of history of history of the Bell System, however as tempting as they are I still have a whole bunch of unfinished projects lined up for The Position Light and I hope you all will still around for them.  These include, but are not limited to:

  • A B&O Main Line signaling survey between Washington DC and Pittsburgh, PA that features most of the now removed CPLs

  • Finishing up the remaining PRR Main Line interlocking towers that I have interior photos for including ZOO, PARK, CORK, STATE and AR.

  • Additional LIRR and METRA towers that I still have unreleased photos for.

These are just the marquee items as I will still keep pumping out the content, rain or shine, good news or bad, 49 posts per year.  Thanks for reading.  Check out my Youtube Channel where I do signaling related live-streams on a somewhat bi-weekly basis.  Also remember to like, subscribe and don't forget to hit that bell notification. 😏

Saturday, May 22, 2021

Approach Lighting - Special When Lit

Today we are going to examine approach lit signals, what they are, their history, how they are classified and finally, who is using them. What they are is in the name.  The signals only illuminate when the signaling system believes a train is approaching (or otherwise nearby). This is one of those things that people are likely more aware of than they think.  The assumption is that a signal should always be lit as that's the way it works in traffic control.  However anyone who lives around approach lit signals are quick to tell me that "those light up when a train is coming" since its hard not to eventually notice the pattern.

Approach lighting actually goes way back to the days of battery operated block signals where workers would have to physically haul out more electrons when any given signal's supply ran low. With LED technology decades away, the first solution was semaphore signals that didn't need electric illumination.  Since this didn't work well at night, a second solution was to link an electric lamp to the track circuit relay in such a way that a shunt of the track circuit would close the lamp's circuit and illuminate the signals.  Since railroad relay logic both then and now allow one input to control 8 or sometimes more other circuits in a single relay, this was a pretty straightforward arrangement.

Typical railroad battery case

Although pure battery based power supplies were eliminated over time, approach lighting remains fairly popular to this day.  The first reason is that 440v pole line railroad power was both limited in transmission capacity and still not reliable and any fault could drop an entire line segment onto battery backup for hours or even days.  The second reason is what most people would assume to be the first, saving on bulb replacement.  while certainly a concern, low watt railroad lamps are pretty long lived as is and we can also observe the behavior of 20th century railroads to determine their motivations.  Where railroad power was plentiful and reliable, think the PRR's electrified region with 6.9kv 100hz supplies or something like the N&W H-Line that was fed by a kv range 3 phase line supply, signals were lit full time where elsewhere on the same railroads approach lighting was employed.

There are several general classes of approach lighting that I have arranged into bins of my own design.

  • Type 1: Type 1 approach lighting is where a signal illuminates only when it's approach block is shunted.  It's the simplest in concept and can be readily observed as when the tail end of a train passes the signal, the signal will deluminate.

  •  Type 1a: This is an even more extreme version of Type 1 where on a multi track line a shuntedn will only illuminate the signal that governs it.

  •  Type 2:  Here a signal location in CTC or other bi-directional territory will illuminate in both directions if either approach block is shunted. Therefore the signal will remain lit for a further period of time once the end of the train passes.

  •  Type 2a: Same multi-track effect as Type 1a, except also in both directions.

  • Type 3: Here a signal will illuminate if a shunt exists within the entire line segment either in advance or in rear of the signal.  This is most applicable in single track CTC or Bi-directional ABS territory and may or may not actually exist in real life.  

  • Type 4:  Another possibly theoretical example would be an approach lighting scheme at interlockings where signals will illuminate if a route is displayed, regardless of (or in addition to) track circuit status.

At this point I have only ever fully confined the use of Types 1 and 2 approach lighting, however a number of anomalies have hinted at Type 3 or 4. There is of course another major exception to these rules in the form of non-circuited track like sidings, secondary tracks or yards.  Signals governing these tracks must remain lit at all times as there is way to detect an approaching train. 

Amtrak Hudson Line CP-156 showing the 24/7 lit siding dwarf and approach lit main track signal.

 Use of approach lighting has varied widely in the time since power limitations became less of a driving force.  Even where power is still provided by a pole line or solar panel, LED lighting would allow for 24/7 display of signals on a fairly small power budget.  There is a small safety boost in that wayside signals can serve as an additional method to alert workers of an approaching train, however it is too unreliable to ever be codified into a rulebook.  Even aggressive users of approach lighting will often make exceptions, especially in built up terminal areas once again pointing to power availability or signal access as a major factor.

At this point Union Pacific is the most aggressive user of approach lighting, employing Type 2a in all of its most recent signal projects.  NS on the other hand is likely the Class 1 most in favor of 24/7 signals, often replacing Conrail era approach lit signals with full time.  CSX uses a mix, but tends towards full time in contrast to the B&O, which was very much in favor of Type 1.  Unfortunately I don't have enough experience with BNSF, CN or CP to comment on their specific tends however at a regional level the old Guilford favors approach lighting while the Reading and Northern splits the difference with full time at interlockings and approach lit at intermediates. 

UP acting like its charged by the photon.

On the passenger side of things approach lighting is much less common as commuter railroads operate in dense metros that have has reliable electric power for well over a century. New Jersey Transit was probably the biggest user of approach lighting and with 1 mile blocks on many of its trunk lines it is possible to observe the next signal light up like a Christmas tree after passing the one before it.  However new Rule 562 territory as well as the RiverLINE light rail have both tended towards full time.  Amtrak used to use Approach lighting on its diesel lines like Michigan, Springfield and Atlantic, but has trended to towards full time, although the new CP-138 on the Hudson Line is approach lit. The other major commuter carriers such as Metro North, LIRR, SEPTA, MBTA, Metra and Caltrain all use primarily full time signals. 

NJT signals at SAUK interlocking are Approach Lit, while those protecting the drawbridge at the joint Conrail interlocking CP-JERSEY are not.

From an fan perspective, approach lighting definitely has its pros and cons. Dark signals are certainly less interesting than lit and deprives one from being able to observe any routes lines up in advance.  However the ability of approach lighting to act as a train proximity warning is highly useful, although could likely be replicated by a radio scanner. It also causes use of a so called "two minute drill" to get photos of displayed signal indications in the time between when a train enters a block and then passes the signal (or passes the signal and then exits the following block).  Salience of the two minute drill actually confirmed the operation of mid-block Signal Indication Points on Conrail's cab signal territory as the approach lighting would only trigger once the approaching train passed the mid-block SIP instead of the previous wayside signal location, thus turning a 2 minute drill onto a 1 minute drill.

That's probably more than you needed to know about approach lighting.  Unlike a lot of signaling trends this one is pretty neutral with neither definite trends in its use nor any major effect on the ecosystem either positive or negative.