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.
I've mentioned this phenomena before, but in this day and age when a Class 1 appears to have "forgotten" about some bit of classic signaling its usually because they intend to sell the line or they are planning something much more drastic than a re-signaling project. Usually this is complete signal removal (I'm looking at you Buffalo Line), but in the case of the largely PRR signaled NS Fort Wayne Line west of Alliance, NS apparently had in mind a radical single tracking project.
Currently the Fort Wayne Line is double track from the Cleveland Line split at CP-ALLIANCE (MP 82) to CP-MACE (MP 110), CP-ORR (MP 124) to CP-BIG RUN (MP 138) and CP-MOHICAN (Mp 157) to Crestline (MP 188). The line has always been a step child after lost traffic was diverted up the Cleveland Line to the Chicago Line. I would not be surprised if the line had managed to stay PTC exempt due to light traffic. The current Conrail era CTC signaling dates from the late-1980's and matches that installed on the former PRR Middle Division.
In 2022 NS released the following single tracking plan that would result in the likely retirement of all remaining PRR position lights on the route and also bring the curtain down on the last major instance of PRR signaling on NS.
Retirement of selected double main line track operations into single signaled bi-directional track (Rule 261).
Approximant limits of project will be PC 84.8 to PC 188.3 on the Fort Wayne line of the Pittsburgh division.
Retire one main track at mile posts PC 84.8-96.7, 157.3-160.1, 161.9-169.4, 178.0-188.3. Change method of operation at mile post limits of 160.1-161.9, 175.1-178.0 to Non Controlled Track.
The good news is that as of 2022 no movement has been made on activating this plan and the recent manpower and capacity problems might cause some change of heart. Regardless, get out to Ohio and get your photos ASAP.
In the realm of railroad interlocking machines, what does this...
Have in common with this...
Well they are kind of the same thing, the latter just being an improved version of the former that does away with most of the sweat and tears. Just like dinosaurs evolving into birds, 19th century mechanical interlocking systems evolved into smaller and lighter form factors with more and more automation until the technology reached its ultimate dead end. It might seem that a Union Switch and Signal electro-pneumatic power frame is a completely different piece of kit than the "armstrong" monsters that came before, but if we lift the hood we can see how the past influenced the future.
Setting aside who invented what and when, by the end of the 19th century there were two common mechanical interlocking styles coming out of the UK. The Style "A" Machine used a vertically oriented interlocking grid where lever bars on the Y-axis would interact with locking bars on the X-axis via a system of tappets. This style is what tends up show up in books and diagrams as it is the easiest to visually digest. The other system was the Improved Saxby and Farmer Interlocking, this used a horizontally oriented locking grid with lever bars moving in the x-axis interacting with locking bars in the z-axis via dogs. Regardless of the terminology, the key takeaway here is that there were two primary interlocking systems and Union Switch and Signal wound up with the US license for the Improved Saxby and Farmer variety.
Above is an IS&F implementation at the abandoned Buffalo, Rochester and Pittsburgh Railway tower at C&M Jct near Du Bois, PA. We can see how the lever bars are engaged by rotating shafts. The shafts were in turn attached to cranks that were in turn engaged by rockers that changed the back and forth motion of the large interlocking lever into an up and down motion that then rotated the shaft, ultimately sliding the interlocking bar back and forth in the x-axis (if the interlocking conditions allowed). In the photo below we can see how the rockers engage with the cranks behind the row of levers on an more complete lever frame.
So what does this have to do with a Model 14 machine? Well if we literally lift the hood we immediately find the exact same style of longitudinal lever bars, just slightly smaller and more compact.
Because on "power" interlocking machines tower operators no longer needed large physical levers to throw the switch points via a long length of pipe, all the complex mechanisms needed to convert the back and forth lever motion into longitudinal motion can be replaced by a miniature rotating crank.
In case you were not yet convinced, the shafts that used to move the lever bars in the x-axis are still around to engage with the locking magnets controlled by the relay logic elsewhere in the tower.
In contrast, the other major type of North American pattern power interlocking machine, the GRS/Taylor "Pistol Grip" type, used the vertically oriented type of locking grid.
This horizontal vs vertical orientation explains why the largest Style "A" type frames were often in tall/narrow buildings, like STATELINE while the largest IS&F frames were in squat buildings such as DOLTON JCT.
STATELINE Tower Outside
STATELINE Tower Inside
DOLTON JCT Tower Outsde
DOLTON JCT Tower Inside
The US&S "Model 14" type interlocking machine was not even the final iteration of the Improved Saxby and Farmer type interlocking! That distinction belongs to the Westinghouse Brake and Saxby Signals Style V machine developed for the London Underground in the 1950's and used as late as 1967 for the all new London Victoria Line. The Style V was a Model 14 style locking bed turned on a vertical orientation with the levers being remotely actuated, typically using compressed air, allowing the interlocking to be remote controlled. I will probably give Style V's their own post at some point, but I wanted to give them a little shout-out in this context. Here we can see a Style V in action a bit after 1:31:25 in a 1960's Victoria Line construction public information film.
In its time railroad signaling was at the vanguard of high tech right along with the telephone system. With the pace of technology today, it is hard to believe that the concept of IS&F mechanical interlocking would be in use from before electric traction was invented up through the ATO equipped Victoria line. I guess it will sort of be how flavors of Z80 microprocessor will be in mainstream use, decades into the future.
I caught a tweet showing off some on Pentrex videos that had been uploaded to Archive.org documenting Amtrak's 1992 vintage Northeast Corridor. I've seen a number of these before and they are a pretty by the numbers affair with a mix of cab and trackside VHS grade video shots with occasional narration explaining things I already know. Well this time, on a hunch, I scanned through the runtime and discovered some rather lengthy segments filmed inside A and ZOO interlocking towers when they were open and handling NEC operations. A would be taken over by the new Penn Station Control Center in 1994 and ZOO would have its NEC functions transferred to CTEC in 1999.
The A tower segment begins at 6:10 and the ZOO tower segment begins at 1:06:45. Some interesting things to note is that A was staffed by a train director, two levermen and three assistants to the train director, although one or more may have actually been telegraphers. In 1992 most of the northern NEC would have been tower controlled with HUDSON closing in 2003, DOCK in 2017 and UNION in 2009. ZOO is staffed by a daytime crew of 4, a train director, leverman and two assistants to the train director, although I was informed that one of these assistants would be responsible for the NEC portion of the interlocking machine under supervision of CTEC. In 1992 ZOO was still hangling Conrail moves over the High Line.
Anyway enjoy. Hopefully this video will continue to fly under the radar and stay online.
The Guilford Rail System and to some extent is predecessor Boston and Maine Railroad, had a reputation for stinginess despite being one of the more "interesting" railroads signal wise. In 2014 the formerly Guilford owned Connecticut River Main Line was restored for passenger operation that had been routed off the line in 1987 due to poor track condition. I took a trip over this route via Amtrak's Vermonter in 2021 and posted a trip report covering the new Guilford style LED target signals, bracket masts as well as surviving instances of searchlights both in Massachusetts and on the New England Central owned portion of the line in Vermont north of the Mass border. However I missed something pretty important in that trip report that only became salient when I was processing all of the photos. Before I try and explain it I'll show a sample of the pre-rebuild Guilford Employee Timetable for the route.
At first view this looks like a pretty common Rule 261/CTC setup, an interlocking, some bi-directional intermediates. However if you look closely you'll see that each of the two intermediates, shown at mileposts 2 and 7, are distant to the CPR-1 and CPR-9 (not pictured) respectively. That creates a rather unusual 5 mile long block in the middle of the bi-directional single track section that would be broken up by an industry standard 2-3 mile long block. Although this setup was modified in 2014, it was not modified much with a new interlocking CPR-2 eliminating the very long block with a dual distant at milepost 5 for a relocated controlled point CPR-8. The next line segment had a 6.5 mile northbound block replaced with another two 3 mile blocks with the milepost 13 intermediate. However the third line segment is where things go off the rails again with a massive 8 mile long automatic block between the mileposts 20 and 28 intermediates.
The CT River Line changes ownership at the Massachusetts border reflecting the historic split between the Boston and Main and the Vermont Central. No matter the ownership however, where the line had been upgraded from Track Warrant/Form D to CTC, the block lengths are reasonable, however wherever the Boston and Main had installed CTC, megablocks are the norm. In fact, on the former Boston and Maine signaled territory controlled by the NECR, the situation is even worse with the intermediate signals acting as single direction distants only similar to Amtrak's 562 cab signal territory, just without the cab signal blocks. The controlled signals in advance of the single track segments are the only indications of block status until the distant signal 2 miles short of the next interlocking.
This creates automatic blocks of 6 miles south of Putney, 11 miles south of Bellows Falls, 10 miles south of Wapole , 14(!) miles south of Claremont and then a comparatively reasonable 6 miles south of Windsor. North of Windsor a new CTC extension has reasonably spaced blocks of about 3 miles each. At the time of my journey I figured I was just doing a bad job looking out for and photographing intermediate signals, however upon further review I wasn't missing anything, The Boston and Main had employed CTC with manual block distances and setups. If this had been the PRR they could have replaced Clear, Approach and Restricting indications at the ends of sidings with Clear Block, Caution and Permissive Block.
While this sort of layout might seem to be a clever twist of frugality, it is in fact an example of the adage "The Stingy Man Pays the Most". Not only is the capacity not much better than with manual block/track warrant, ANY track circuit failure in ANY of these super blocks will result in a Restricting signal indication at best or, more likely, a permission past stop signal. The next choice is a 10 mile slog at Restricted speed (elapsed time 30+ minutes) or a dispatcher process to temporarily replace signal rules with TWC/DCS rules if that is even possible thanks to whatever is causing the track circuit problem, like a broken rail. This explains in part why the poor maintenance of the Guilford years formed Amtrak to move off the CT River Line and seize by eminent domain the segment between Vermon and Windsor. Any signal problem would instantly cause a 30 minute delay in addition to all the bad order track. In summary this setup might work for low density lines with some passenger trains that need better protection than track warrants. However if track circuit integrity is taken seriously, this setup is highly fragile. It's no wonder that setups such as this are somewhat more popular with axle counters substituting for track circuit integrity.
If you recall my musings on Tower Window Syndrome, you might recall that as towers age, their original windows are replaced by cheaper replacements from the local home improvement store or just plywood. The famous ZOO tower in Philadelphia wasn't the worst example of this, but it was an example as its once full compliment of windows was slowly reduced in size and number.
Over the last few years ZOO tower was given a brand new set of windows and a set of replica PRR keystones to boot. This seems strange for a tower is facing closure within the next decade or so unless someone at Amtrak is just really into historic preservation.
Well while talking with some folks at the Harrisburg Chapter NRHS I was informed that there are plans afoot to not only preserve ZOO as an ancillary railroad structure (like a signal maintainer base), but turn it into some sort of museum. I am not sure how far along these are, but it would explain the new windows and historic markings.
While certainly a possibility and also an amazing location near the actual Philadelphia ZOO where tourists could view the NEC, there would be a few hurdles creating marking from the Amtrak employee lot and providing a walkway across the active NY-PGH Subway track as well as additional fencing and whatnot for liability purposes. Still, the idea of a preserved ZOO with a restored 230 lever US&S interlocking machine and model board would be a fantastic end to a century of service.
I recently had to the privilege of riding Amtrak's second daily round trip to Roanoke, VA, allowing for single day excursions to the Star City. A similar second round trip was added to Amtrak's Norfolk, VA service and together these two trains represent the only scheduled Amtrak service on former Norfolk and Western trackage and therefore the only way for one to experience N&W signaling in person. An added benefit is that the reverse peak Roanoke train uses the shorter NEC morning/overnight trainsets with 2+1 seating Business Class section on the rear of the train which provides a railfan view. This would also be my first opportunity to survey the former Southern main line with a unobstructed rear view since Amtrak reversed their LD trainsets in 2015.
The first observation is that NS did not restricting signal capabilities to most of their interlocking signals during their most recent re-signaling protect in the mid-2010s. This allows a train to follow closely behind another in the same direction. Instead following movements need to wait for the leader to clear the block or get permission past the stop signal. Providing for Restricting likely adds a bit more signaling logic to establish direction of traffic. Another change from the former Southern arrangement was that equilateral turnouts have now been given an explicit straight and diverging routes even though both routes have the same speed. On the N&W there remained examples where both routes at the end of a double track segment could get a "straight" clear.
Equilateral turnout with "diverging" route and no restricting at RIVERMONT
Equilateral turnout with "diverging" route and no restricting at RIVERMONT
South of Lynchburg where the Regionals change between the former Southern and N&W Main Lines, there is an uncommon "full complete" Southern aspect system signal with three lamps with three lights each. The presence of a bottom head is due to the slow speed route to the double wye N&W connection in addition to a medium speed crossover route. It is unclear how approaching movements are informed of the difference between the two routes, but it is likely that *Y*, Approach Restricting, is employed. Although the next signal will not display a Restricting, the former Southern RR rule book listed *Y* as Approach Slow. In theory Approach could also be used. Regardless, this would be a good location to observe the scheduled Amtrak Roanoke movements.
Full complete Southern type signals on both tracks at MONTVILLE interlocking.
In downtown Roanoke there was quite the amazing track and signal complex. Although all of the N&W Position Lights and pneumatic point machines have been removed, the sheer quantity of appliances all visible from the Amtrak Station or public streets makes the location a must visit. Oh, there are also two N&W interlocking towers standing at either end of the corridor.
PARK ST tower visible past a variety of N&W pattern color light signals in downtown Roanoke.
The N&W signal system has a few speed indications, specially in the area of dwarf signals due to the use of PRR type position light dwarfs. Slow Approach (*Y*), shown below for the departing Amtrak trainset, is only able to be displayed on a dwarf signal and also happens to match the NORAC version. Placement of the yellow lamp in the center of a R/Y/G arrangement also allows for Y/G Approach Diverging and R/G Diverging Clear.
On the former N&W Blue Ridge Sub, we had to do a pull-in pass due to long PSR specials hanging out on the main tracks. At WEBSTER interlocking we pulled forward into an occupied block, waited for an opposing train of empty hoppers to pass by over a Diverging Clear, then reversed with a permission past the stop making it likely that the lower head Y on track #1 was for Y/Y Advance Approach and not R/Y Restricting as per the previous commend about lack of Restricting indications.
I'm sure I could go on, but those are the most relevant points from my first passenger train journey over signaled N&W trackage.
The problem with PTC and railroad safety regulation in general is that, despite having a lot of interest from transportation planners, advocates and enthusiasts, rail is still a pretty niche industry so when a "Think of the Children" type moment occurs there's not much in the way of interest groups to push back on ill conceived regulation or legislation. The Positive Train Control law is the poster child for this sort of bad lawmaking, but because rail has made itself so less salient than air or road transport, the complaints were falling on no ears. Well, it appears that this may be changing as some more main stream publications are picking up on the massive waste of resources PTC has been.
A recent article from the right leaning pro free market publication Reason actually puts the annual cost of maintaining the PTC system at a staggering $850 million per year to maintain. To put that in context, that is the cost of a starter light rail system that is pretty much being set on fire instead of being used to perhaps build a light rail system. The article is quoted below, but just keep the $14 billion install cost and ~1 billion annual costs in the back of your pocket when someone trots out the old "safety is worth any cost" argument.
Railroads
spent a decade and billions of dollars fulfilling a costly federal
mandate, at the expense of addressing less eye-catching causes of
rail-related deaths.
Reason.com by Christian Britschki June 28, 2022
The
latest Amtrak crash near Mendon, Missouri, that left four dead and many
more injured contains a tragic lesson about Congress' misaligned rail
safety priorities.
The
accident occurred yesterday when an eight-car passenger train traveling
from Los Angeles to Chicago derailed at a grade crossing after striking
a truck that was obstructing the tracks. Three passengers and the
driver of the truck died, and 150 were taken to nearby hospitals.
The
grade crossing was "uncontrolled," meaning that it had no crossing
guard arms, warning lights, or other safety features that are typically
employed to prevent accidents at road-rail intersections. Accidents at
grade crossings are a large portion of rail-related deaths.
According
to safety data from the Federal Railroad Administration (FRA), 236 of
the 896 rail-related fatalities in 2021 happened at highway grade
crossings. Of those, 33 involved Amtrak trains. The vast bulk of the
other deaths involved trespassers on railroad property getting struck by
trains. There were also 168 suicides by rail in 2021, which the FRA
reports separately.
This
particular grade crossing has apparently been on the radar of both
state officials (who had a plan to install safety improvements) and
neighbors. In the wake of yesterday's accident, one farmer who lives
close to the crossing complained to local media about the lack of safety
features and the steep climbs that made it hard to see down the tracks.
Despite
the frequency of fatal grade-crossing incidents, the major rail safety
push over the past decade has been to prevent train-on-train collisions,
high-speed derailments, and other exceedingly rare high-casualty
events.
In
September 2008, a passenger train in California collided with a Union
Pacific freight train, killing 25 people and injuring 135.
A
month later, Congress passed the Rail Safety Improvement Act that
mandated railroads adopt Positive Train Control (PTC), an expensive
suite of automation and communications technology that can automatically
slow speeding trains down.
A
common feature of federal safety legislation is that it adopts a very
expensive solution to solving the last, most media-salient incident
while ignoring more modest safety improvements that could prevent the
more ordinary tragedies that capture less attention.
The PTC mandate was no exception.
It
cost railroads an estimated $14 billion (about $2 billion of which was
covered by federal grants and loans) over a decade [OK?] to comply with
the PTC mandate, which was eventually fulfilled in 2020. The
cost-benefit analysis of positive train control has never looked
favorable.
The
FRA estimated that the technology would provide about $90 million in
safety benefits each year while costing $850 million to maintain. An
earlier estimate by the agency found that it would have prevented seven
fatalities over the course of a decade. (The infrastructure law passed
by Congress last year does, to its credit, create a grant program to
help pay for much-needed grade crossing removals, which probably should
have been prioritized sooner.)
That
the money spent on PTC provided little return in terms of safety
improvements is only one problem with the mandate. Each dollar that went
to the technology was one that couldn't have been spent on more
efficacious safety improvements.
According
to local ABC affiliate KMBC, Missouri officials estimated the costs of
improving the Mendon crossing at $400,000. So it's possible it could
have been improved long ago but for an expensive PTC mandate.
Just remember that Safetyism is a bi-partisan affair. The PTC law was signed by GW Bush from a Democratic congress and subsequent Republican administrations did nothing to attempt to get rid of it. Some might say PTC has been most successful policy to kneecap passenger rail that nobody has ever heard of.