A blog devoted to explaining the ins and outs of North American railroad signaling, past, present and future. This blog seeks to preserve through photo documentation the great diversity and technical ingenuity of 20th century signaling and interlocking hardware and technology. Related topics cover interlocking towers and railroad communications infrastructure.
Note, due to a web hosting failure some of the photos and links may be unavailable.
Well the famous "Racine" position light signals inbound towards the north end of Chicago Union Station were suddenly replaced last week. If anyone was ever wondering why there were PRR position lights in Milwaukee Road territory, since taken over by METRA, it is because the former PRR Panhandle Route to Chicago came up the west side of the city, took a right turn and entered Union Station from the north. (This was discussed in my article on Tower A-2).
This was not part of a re-signaling effort, the signals were cut into
the existing interlocking logic one by one over the course of several
nights. The replacements were METRA standard non-Darth LED traffic lights. Fortunately the bomb-proof PRR signal gantry was re-used and will probably live on until the end of time.
Photo courtesy Robert Jordan
While located at the Racine St grade crossing, the signals are officially part of CP-MORGAN, a remote interlocking controlled from TOWER A-2. There are two facing point crossovers with movements made at Restricting speed. Under Metra signal rules the lower LED heads will display R and L.
Photo courtesy Robert Jordan
The signals at the other end of CP-MORGAN were converted to searchlights sometime in the 1980's. Word is that this will be replaced in the near future.
Well a major holdout of classic signals is now gone. Just south of the Ohio River on the route of Amtrak's Cardinal, the juncton of the former C&O and L&N main lines had featured both B&O and C&O signals until just a few weeks ago. One of these, at NX Cabin, was the last C&O signal bridge left on the old C&O Main Line between Newport News and Cincinatti.
This island of signaling had survived because it was involved in a re-signaling programme in the 80's or early 90's and was lower down on the priority list. The main attraction was KC junction, which feature a number of 5 orbital CPL's and some strange hybrid C&O signal bridges that were refitted with B&O CPLs during the re-signaling process. The ones coming off the former C&O main line were notable for their comically large sun shade.
KC junction also featured a massive 3 story L&N interlocking tower, but it was demolished sometime within the last 10 years. I do not know the state of the CPLs at the adjacent OB Cabin (Ohio Bridge) or A interlocking in Cincinatti, but the smart money is that they have also been removed.
From time to time I have brought up some of the quirks inherent to North American light rail signaling systems. Because they exist in a regulatory and cost grey area (not really railroads, not really subways, able to stop on sight in traffic, etc) the signaling systems they employ tend to be very economical. Well this past summer I traveled to Denver and rode around on its extensive light rail network. There I noticed that the RTD light rail had methodically checked off every box on the light rail signaling checklist and I figured I should share it here.
1.) Missing Wrong Direction Signals
See that little red circle? Yeah, that's plated as a signal because the RTD's commitment to single direction ABS is so complete that all wrong direction movements need to get talked past the stop disc at the next interlocking.
2.) No Distinction Between Auto and Interlocking Signals.
See any difference between the ID plate on the interlocking signals in the first picture and the ABS signal in the second? No? Well that's par for the course on a light rail system.
3.) ATS
Light rail systems don't uniformly lack speed and signal enforcement. They just opt for the budget versions. RTD Light Rail has some sort of loop based ATS on its main line sections, but the operators weren't too helpful in providing the details on how it worked. Of course where ATS proves impractical one gets a nice little sign.
4.) Single Headed Signals.
Light rail systems hate confusing drivers with multiple signal heads, so flashing aspects warn of diverging movements.
5.) Vehicle, Signal Thyself
Dispatchers cost money, so LRVs simply set their destination and let track mounted sensors do the rest.
6.) New Lines, New Rules
How can consultants bill those hours if they just say to stick with the same old thing? Of course the line that just opened in 2017 would have some new signal rules requiring a second head!
7.) US&S N-3's
You look hard enough around a large light rail system and you'll find a US&S style N-3 signal head 😏
Did I miss any? Throw something in the comments and I'll see if I can find an RTD example ;-)
In the late 1930s the Pennsylvania Railroad decided to equip its low grade Columbia and Port Deposit Branch with a state of the art signaling system in conjunction with an equally cutting edge electrification project. The Rule 261 signaling on a single track line with passing sidings was controlled by CTC machines at just two on line towers, PERRY and COLA. Remarkably this signaling lasted over 80 years with the northern half being retired in 2012 and the southern half being retired on April 9th, 2018. Fortunately I had been able to fully document the line as it originally appeared over the preceding decade and a half and you can review my work here.
Compared with other recent NS re-signaling projects that have continued through multiple calendar years, the PRR signaling on the lower 20 miles of the Port Road were replaced in about 6 months. Not only were the remaining PRR position light signals replaced, but NS also decided to convert the cab signaled line to Rule 562 operation, eliminating four automatic signal locations and converting another to a controlled point. Of course I don't need to tell you all of the changes that took place between PERRY interlocking on the NEC and CP-MIDWAY because NS is nice enough to publish comprehensive change documentation that also includes all possible signal aspects.
Starting from Amtrak territory at PERRY, the first major change was the conversion of the former CP-MINNICK interlocking to a new CP-MINNICK controlled point. CP-MINNICK used to provide access to the west end of the Perryville freight yard and was downgraded to an automatic signaling location when the yard was removed. Well, for whatever reason NS decided to install a controlled point cantilever mast in between the two former CP-MINNICK home signals. I guess it allows locomotives and trainsets to be reversed at the Perryville wye track without having to tie up the entire stretch of track south of CP-QUARRY, where NS likes to store trains waiting to get onto the NEC. It could also be a way for the signal department to add what is functionally an automatic signal despite a possible management directive to go Rule 562. Without the signal at CP-MINNICK, crews cannot tell if they are approaching a Slow Approach or a Stop signal at PERRY from their cab signal alone. The aspect chart also shows how the distant to CP-QUARY on the siding track has to display both Approach Limited for a Limited Clear and an Approach Medium for a Medium Approach. Also being wiped away are electro-mechanical cab signal code generators of the type that existed at the cab signal cut between CP-MINNICK and PERRY.
The once and future CP-MINNICK
Moving on, CP-QUARRY has had its eastbound home signal moved to be closer to the switch. Evidently PTC and cab signals are a substitute for sight lines. Also, NS is taking a play from the Amtrak playbook and having trains diverge over Medium Clear at CP-QUARRY approaching a Medium Clear/Approach at CP-TOME and Limited Clear approaching a Clear/Approach signal at CP-TOME.
