How to Patch Your Signaling System (in 3D)

In this week's installment I will travel to Georgia to highlight an interesting development on the CSX Abbeville Subdivision that I discovered while visiting a friend last year and how it ties in with a pet peeve of mine that wound up influencing signaling in the UK. The Abbeville Sub was a former Seaboard Air Line route between Atlanta and the port city of Wilmington, North Carolina. The line is your typical single track CTC with passing sidings and sees only freight traffic including double stack trains.

I have mentioned before that the current practice in North America regarding signaling system alterations is to typically replace the existing signaling even if the existing signaling if relatively new with solid state components. My suspicion is that it is easier to test new signals in situ than to try to patch in new vital logic to the older, in service equipment. However every so often there are exceptions to this rule, usually where a single signal is replaced due to structural deficiency or damage. Less frequently single signals will be replaced as part of a change in the physical plant. (And least frequently will the old hardware be modified.) This post is an example of CSX performing a simple signaling upgrade and only replacing the signals that were directly affected instead of everything in sight.

The location in question is between milepost 506.8 and 513.4 near Athens GA. The upgrade in question was the installation of a new interlocking at milepost 509.6 to serve a large grain customer so that crews no longer had to operate a hand throw switch. Previously there had been an automatic signal at 510.1, an interlocking at the south end of the Fowler Junction controlled siding and another interlocking at the north end of the siding. The distances involved were 2.3 miles between the auto and SE Fowler and 9,800 feet between SE Fowler and NE Fowler. All signaling was of Seaboard origin and dated from the 1970's or early 1980s. On CSX a controlled siding is one with interlocked end points, but no train detection so all diverging moves into the siding receive a Restricting aspect. Signal progression for a Restricting signal on CSX is just Approach to Restricting so the 511 automatic could make do with a single 3-lamp head in each direction. However the new interlocking at milepost 509.6 would split the 2.3 mile long block into two blocks of 1.5 and 0.8 miles respectively. While a 1.5 mile block wasn't a big deal, the 0.8 mile block would be too short for a train to safely stop and it was decided to install 4 block signaling on either side of the short signal block. This would require the signals at the 513 auto, the 511 auto and NE Fowler Jct to display an Advance Approach aspect, which they were not set up to do.

Now had this been working under NORAC, Union Pacific or Canadian signal rules the change would have been trivial because Advance Approach (preceed prepared to stop at second signal) is represented by a flashing yellow (*Y*). However CSX's Seaboard System rules use Y/Y for Advance Approach. This means a hardware modification to install a second head or, completely new signals and that is what the signal vendor encouraged CSX to do. So here we see the new 5110 automatic signal that I happened to catch displaying Advance Approach. Note the old (P) board at the base of the signal which was used in the Seaboard system to mark Permissive automatic signals as opposed to the more common numberplate.

I was pretty lucky to catch the 511 auto displaying Advance Approach as the signal itself is approach lit providing only a brief window of time when a train is in the block where one can catch anything lit up. Aside from the actual signal hardware everything else about the TCB signaling in the area had been left unchanged including the relay cabinet and the original concrete signal base that the new mast appeared to be glued on top of.

This is a good opportunity to explain why I dislike the Y/Y advance approach indication.  The obvious problem which is demonstrated by this complex patch job is that you have to add an additional lamp or signal head when shortening block lengths instead of just setting the yellow to flash.However from a signaling theory point of view Y/Y Advance Approach makes the signal aspects much less consistent. Basic block type signals can no longer all be displayed on one head (or with one lamp). Moreover on CSX Y/Y for Advance Approach displaces what would normally be Approach Slow into a three lamp aspect, Y/R/G. This then serves to dilute the impact of having only absolute signals three lamps as well as disrupting the pattern of the "Approach Speed" series of signals listed below.

Y/R = Approach Stop
Y/L = Approach Restricting
Y/Y = Approach Slow
Y.G = Approach Medium
Y/*G* = Approach Limited

By stealing Y/Y for advance approach the pattern is disrupted. Y/Y was originally the standard way to display Advance Approach and was actually copied by the Big 4 British railways when that system adopted color light signaling in the 1930's.  The reason for this was because at the time flashing relays were both expensive and unreliable, but as technology marched on flashing signals became common and when Conrail was forming what would become NORAC in the 1970's the decision was made to dump Y/Y Advance Approach and replace it with flashing yellows.  The real headscratcher is that even if CSX's embrace of Y/Y advance approach precluded wholesale conversion to the two headed style of Approach Speed signals, the Seaboard rules do not currently make use of *Y* for another indication.  Much like Conrail did CSX has been free to phase it in ever since it embarked on its massive re-signaling spree starting around 1999.

Anyway, in addition to the 511 Auto the 513 Auto also needed replacement to fit Advance Approach due to the now "short" 1.5 mile block between the 511 auto and the new interlocking.  Again had *Y* been available all the original signaling hardware would have been able to be left in place.

According to the Timetable - METRA Beverly Branch

While Timetable and Train Order operation isn't quite dead yet, the "timetable" part of it almost certainly is, even on the one line that officially still uses the system. This is because for all the talk of superior and inferior trains the LIRR does a pretty good job at making sure trains know explicitly when they have to take sidings due to the Manual Block system that covers the more traditional T&TO. Of course that is what I thought until I started going some research on METRA's Blue Island interlocking tower located on their Rock Island division.

Anyone familiarizing themselves with the METRA commuter network may have noticed the strange lack of any automatic signaling system on the Beverly Branch portion of the Rock Island District. The Beverly Branch is an interurban themed loop off the Rock Island main line that sees the majority of Rock Island district trains save for a few rush hour express runs. Running 6.5 miles from Gresham Junction to Blue Island – Vermont Street about 5 miles of that is not covered by any sort of automatic signaling, which under GCOR means ABS or CTC rules. Of course what the line lacks in signals it makes up for in stations with a total of 10 filling the unsignaled section between the new CP EZLIABETH and the 125th St interlocking.

Now unsignaled track, even on commuter rail lines isn't that uncommon, but if one reviews the operating rules for that section you will not see anything pertaining to Track Warrant Control or even its lesser known GCOR cousin Track Permit Control. What one finds instead is Time Spacing, which is defined in a serious of special instructions in the METRA employee timetable.

* A proceed indication displayed by the controlled signals governing entrance to the non-signaled territory or verbal authority from the train dispatcher or control operator will authorize trains which have scheduled passenger stops, as indicated in the Employee Train Schedule, to enter and run with the current of traffic in the non-signaled territory. A train must not follow another train until 10 minutes after the preceding train has departed.
* Road Dispatcher at Gresham Junction and Control Operator at Blue Island must hold trains at the controlled signals governing entrance to the non-signaled territory of the Beverly Sub District until 10 minutes after the preceding train has passed. They must also notify any train which is followed by a train scheduled to precede it.
* Trains not indicated in the Employee Train Schedule as operating via the Beverly Sub District and trains moving against the current of traffic will be authorized by track permit after an absolute block has been established in advance of the movement.

What we have here is a somewhat informal version of timetable operation which keeps the time separation components, but discards many of the issues about actually keeping to your assigned schedule. Only scheduled trains may enter the time separation area on signal indication, but it doesn't matter what that schedule is or if they are following it. The rationale behind this the high density of stations which all trains on the line must stop at. With stations less than one half mile apart each there isn’t much room for trains to build up a dangerous amount of speed and it is not difficult to observe any traffic running on the line ahead.

Even with the frequent station stops and a 30 mph maximum line speed, a second layer of safety is provided by the operators (now dispatcher in the case of Gresham) who cannot display a signal into the time separation without waiting 10 minutes since any preceding train was admitted. This time separation requirement applies for trains within the block which cannot depart a station any time sooner than 10 minutes after the preceding train has departed. The signals at both entrances to the section can either display some version of Clear and Restricting, so just like in manual block systems the Clear served as a manual block proceed indication that is valid all the way to the next interlocking, unless the train is held up by the at station 10 minute rule. At the new CP-ELIZEBETH (replacing a portion of the old Gresham Junction interlocking) you can see the proper direction track westbound signal can display G/R on the upper head and R/L on the lower. The reverse track can display G/R/L on the lower head.

While in theory time separation could be employed equally well on a bi-directional scheme with admittance to the blocks governed by the operators/dispatchers at either end, in practice all reverse direction moves must get a track warrant. Moreover all non-scheduled trains must also get a track warrant as no scheduled train skips any stops and the station stops serve as safety critical time checks.

Unfortunately all these stops come at the cost of timeliness with the 5 miles in the un-signaled territory taking upwards of 20 minutes to traverse according to the schedule. That means that the line would not do much worse if it was simply converted to Yard Limits and trains run at restricted speed (although you might not be able to make any stops). In terms of train frequency the shortest headways on this line are 13-14 minutes apart, although to handle the peak traffic other trains can be sent via the Main Line with its full CTC protection.

In advance of each exit interlocking, CP-ELIZABETH to the east and 125th St to the west, there is an automatic distant signal allowing the block in advance of exit interlocking to be run under ABS rules. The setup is reminiscent of Amtrak style Rule 562 operation with cab signals with fixed waysides only at distant.

The history behind why this stretch of line was left signaled the way it was is a bit of a mystery, especially considering that the Rock Island was the first to make use of RTA funds to improve its service. One probably culprit are the large number of grade crossings in the Beverly Hills section of the line with 24 being located in the unsignaled section. Automatic crossing protection using DC track circuits would have required complex logic when combined with automatic block signaling. Demands from the time to improve crossing protection or an effort by the Rock Island to avoid paying crossing tenders may have lead to the discontinuance of automatic signaling in that area. The practice may have also evolved from older manual block or timetable operation that was never upgraded due to the slow speeds and frequent station stops.

How much longer this practice will continue is a matter for speculation. The Rock Island district is already targeted for a pilot PTC system and such dark territory is the thing that PTC generally eliminates as part of required signaling upgrades. However PTC could be used as an overlay to provide actual enforcement of the current time separation and remove any necessity for track circuits on this stretch of track. The time separation rules would of course probably be left in place for when the PTC system inevitably doesn't work.

Another Signaling News Roundup

Time for another post grouping all of the recent signaling news.  As always CSX is re-signaling something and this season their cancer has spread to the Philly Sub with new signaling going in between ROSSVILLE and the Van Beibber siding.  Automatics appear to be included as well including the late model pair between ROSSVILLE and BAY VIEW.  This is a bit sad as ROSSVILLE was re-signaled about 10 years ago and the autos were converted to modern audio-frequency circuits about the same time.  The Van Bibber siding is still relay equipment so I guess its not surprising.

Staying with CSX new signals are up on the former C&O main line at Fostoria which had remained a breath of fresh air ever since the B&O main line re-signaling in the late 1990's.  However it seems that the reprieve is up, even for the C&O aspect Darth Vaders.

 Its a CSX Hat Trick as I learned that the new signals on the C&O Main Line between MX Cabin (Hinton yard) and Alderston were just cut over so there is increasingly less reasons to take the Cardinal to and from Chicago.

 Moving down south we find a major re-signaling project in the Birmingham area as the 32nd St interlocking complex is going under the knife from NS.  In this case the signaling itself may be getting more interesting as the original Southern plant was rather minimalist, but the new Darth Vader heads are just as bland even if they are displaying new aspects.  Also going are R/ / Y restricting indications which are somewhat special.  If you life down there use the convenient grade crossing to get some closeup pics.  This follows the re-signaling of the re-signaling of the large 3x2 diamond crossing at 14th St.

Mystery Searchlights Revealed

Last August I reported on a strange type of searchlight signal being installed by Canadian Pacific.  Canadian Railroads had, until recently, been supporters of the searchlight signal style switching to Unilens and 3-color LED's as electro-mechanical searchlights fell out of favor.  Well, Unilens signals had always gotten a bad rap when it came to beam intensity and I noticed that in pictures of the new signals around the Mechanicville Yard complex that what was being installed didn't look familiar and also, from external reports, were quite bright.  Well, I finally up to the area to check things out.

It turns out that these searchlights are indeed not of a traditional type or made by a traditional manufacturer.  While they roughly look like old school searchlights the housing is quite a bit larger and unfortunately did not provide any clue to the type of mechanism inside.

A closeup of the builders plate shows that these aren't even made by a signal vendor, instead a custom steel housing outfit in Manitoba.  So it looks like for a time CP was going in house to supply its signaling needs.  If these were to more reliably house old school searchlights or a new housing for some sort of LED based unit perhaps using a mirror system I do not know,, but I suspect I will find out eventually.

Looking down the barrel there appear to be LED elements behind the traditional focusing lenses, which is not surprising seeing that CP has now flipped to bare LED Darth Vader units.  unfortunately while some light was shed on these mystery searchlights I unfortunately discovered another variety at CP-448 on the Guilford Freight Main Line in Eagle Bridge, NY.  Oh well, give me something to do the next time I am in the area.

PHOTOS: CPL Theatre - VINE and LOCUST

Well once again it is time to turn some hum drum interlocking photos into some sort of cohesive narrative on signaling. In today's installment I bring you VINE and LOCUST interlocking on CSX's Philadelphia Subdivision. These two interlockings are located back to back about 1/2 mile from eachother on the former Baltimore and Ohio line along the Schuylkill River in Philadelphia. Located just 600 feet from the far more impressive Pennsylvania Railroad Northeast Corridor and its 30th St Station, the B&O line was always a distant second in the City's transportation pie...taking you the same places the PRR could, just in a lot longer time.

Now technically the B&O line ended at VINE, but during the golden age of railroading the line made a connection with PRR antagonist Reading Company which had an alliance with the B&O to allow it access to the major New York area market. Now as I said the B&O's route between Washington DC and New York was hopelessly outclassed by the PRR's mega main line, even more so after the latter built tunnels directly into the heart of Manhattan and then electrified the whole kit and kaboodle. Their response was to try to compete on quality of service in the form of the daily Royal Blue service. This train would be handed off to the Reading at Philadelphia, then take Reading tracks to Bound Brook, NJ where there would be another hand off to Reading subsidiary Central RR of New Jersey, which would then take the train to its final destination in Jersey City where the passengers would leave their super luxurious train and board a deluxe...*sigh*...bus, to go the last few miles to Midtown Manhattan. Needless to say this train did not survive long into the era of the Eastern Shuttle between NY and DC.


Now this stretch of track along the east side of the River had two main uses. The first was passenger service with the B&O's 24th Street station located right there. The second was freight traffic to and from New York via the Reading, but the 1976 consolidation of the bankrupt Reading into Conrail ended these movements. Even in 1999 when CSX bought half of Conrail to regain access to New York, most traffic ended up bypassing this stretch via a connection to the West Philadelphia Elevated due to the clearance restrictions caused by the Art Museum tunnel. The upside of all this irreverence has been that since whatever signaling associated with the 24th St station was removed in the Chessie System era, what they put in for replacement has stayed intact to this day and that mean, you guessed it, the whole corridor is sprinkled with B&O style colour position light signals.

Now despite these two interlockings being located in a deep depression adjacent to the river on one side and a retaining wall for the city centre on the other, the City was awesome enough to install a Multi-Use Trail between the tracks and the river, allowing near perfect access for the purpose of documenting the signaling there. There's even a cute little level crossing for the pedestrians and cyclists, but more on that later.

Anyway we begin with LOCUST interlocking which is named for proximity to Locust St. LOCUST consists of a basic crossover and the western end of the old B&T Philadelphia terminal area between here and RG Tower where the freight yard is located. South of LOCUST in addition to the two main tracks there is also #3 and #4 Running track which are used to park freight trains for various reasons. In this photo we see the westbound CPL dwarf signals, which are dark due to approach lighting, and a freight train way in the distance parked on the running track. The principle freight traffic that uses this line are municipal waste trains to and from large transfer stations in New Jersey and Staten Island that cart away the endless stream of refuse from New York City en-route to points south. The running tracks are a popular place for CSX dispatchers to park returning empty trains until they are needed up north.

The track #1 CPL dwarf consists of a full central target with the 12 and 2 o'clock orbitals attacked. The 12 being for straight routes and the 2 for an Approach Slow for mores at GREYS FERRY interlocking. If you are wondering about diverging moves at LOCUST itself the switches only good for 10mph, which is 5mph less than the official "Slow" speed so they have a special note in the Timetable. Diverging moves are covered by either a flashing | for Slow Clear or a solid | for Slow Approach Slow.

The track #2 dwarf is the same as the #1 dwarf except it lacks the 2 o'clock orbital for Approach Slow. GREYS FERRY has another one of those 10mph turnouts for diverging moves only from track 1 to 2 westbound so at LOCUST all that is needed is Slow Approach Slow, which does not light an orbital. The lunar white Restricting \ is displayed for movements into the non-circuited #3 running track.

Now a couple months later a cut of 85 foot flatcars each with 4, 1 TEU garbage cubes parked on #2 track was lighting up the dwarf signals. In this zoom shot you can see the interlocking along with another cut of 85 foot garbage flats which was probably split to avoid fouling the interlocking and the crossing.

 Here we see each of the westbound CPL dwarfs lit up from a slightly off angle.

An Interlocking By Any Other Name

If there is one thing that can be considered constant in the world of railroad signaling, apart from mileposts that is, it would be interlocking names.  Interlocking names tend to hang around even as towers are closed and signals replaced.  Now sometimes large plants are broken up into smaller ones and telegraph codes may be replaced by names and names replaced by CP numbers, but there are numerous cases of interlockings keeping the same name through 3 or 4 owners over a time period of a century or more. 

While out documenting some searchlight signals on the former Delaware and Hudson territory in Upstate New York I came upon a unique piece of living history several miles west of Mechanicville where the generically named Canadian Pacific "Freight Subdivision" joins with a connector track to Rotterdam Junction westbound and a 9000 foot siding eastbound.  As you can see the relay hut for the interlocking plant is suffering from a bit of an identity crisis.

As the intra-interlocking pole line cable may give allude to, this interlocking plant has clearly been in service for a number of decades and the relay hut has no fewer than four different nameplates identifying it three different ways.  Solving this puzzle will take one back in time through a tangle of corporate ownership, but fortunately its not too difficult to figure out what is going on here.

The oldest name is the QS telegraph code which is the original D&H name and was probably taken from the tower that used to be at this location.  At some point the D&H caught the CTC bug and when the number of interlockings exploded, instead of trying to make up new call-signs some clever person in the D&H front office just went with a popular variety of the CP system with a suffix indicating the particular subdivision.  In this case the Subdivision was F for the "Freight" Subdivision which ran from the Boston and Maine interchange and massive yard complex at Mechanicville to the interchange with the former Erie and DL&W lines in Binghamton with further connections to Scranton.   This new organization reflected the growing importance of freight flowing to and from the New England ports over freight to and from Canada and also opportunities granted the D&H during the Conrail merger where the smaller railroad was given expanded track access to help "compete" with the semi-nationalized northeast freight monopoly.  So the new designation of the old QS interlocking became CPF-10 as it was 10 miles from the start of the line in Mechanicville.

In 1984 the B&M successor Guilford Rail System and its eccentric owner bought the ailing D&H for essentially pocket change and because he now had a lot more railroad to play with the owner decided to fully integrate his existing 'Freight' Main Line, which ran from near Brunswick, Maine through to Mechanicville, with the D&H line to Binghamton.  Out went the millage reset and in came a new set of three digit numbers from 467 to 611 and CPF-10 became CPF-477.  GRS ran the D&H into the ground so badly that the D&H portion of GRS went bankrupt in 1988 and Canadian Pacific was eventually brought in to take it over.  Now CP Rail wasn't about to go all wacky and re-name things yet again, but it did eventually come by and attach new nameplates on the relay hut. 

One result of the CP takeover of the former GRS integrated line is that the CP trains which run primarily to and from Canada (just like the D&H trains did) start off at MP 611 in Binghamton, run to milepost 480 north of Schenectady and then continue straight ahead onto the Canadian Sub with its new mileage system starting at Milepost 21 (facepalm).  Oh, and CP trains making the turn to stay on the Freight Sub will continue to count down to 468 at which point they turn onto the Colonie Sub at Milepost 19 which will then count down to zero at Albany.

CPF-477 of course is not the only interlocking to show off at least some of its heritage.  One mile to the west CPF-487 still shows the signs of its original name, QG.  Unfortunately CPF-478 and other interlocking plants along the line are being re-signaled and the new relay huts aren't going to have their naming history transferred over.  One example that might survive is the old hut from CPF-130 (that's D&H CPF-130) now serving as the housing for the radio repeater at CPO-4 on the Colonie Sub in Watervillet. 

So the lesson for everyone is to think long and hard before you go and re-chain your rail line because if your expansion plans get undone its going to create major headaches for decades to come.

CALUMET Tower Closes and Other News

Well this one certainly came in under my radar, but CALUMET tower located on the Indiana Harbour Belt where it crosses the CSX (BO&CT) main line in East Calumet City, IN just closed in early March 2013.  CALUMET was a very old mechanical tower with all the looks and structural integrity of METRA's 16th St crossing only containing a 96-lever National Switch and Signal (later bought by US&S) mechanical lever frame which would help to hold the tower up better.  Calumet Jct consists of the triple crossing between the IHB, B&OCT and EJE lines with the IHB and EJE each crossing the B&OCT on a set of 6 diamonds and then the EJE crossing the IHB via shallow angle movable point diamonds.

 Like all other surviving interlocking towers CALUMET lost a lot of complexity over the years and like DOLTON junction it had its mechanical points swapped for the power operated variety and most of its classic signals swapped for Darth Vader masts, but its ease of access and location at the crossing of two major main lines made it a very popular railfan hotspot, although only for those willing to brave the bad neighborhood it was in.  While no scheduled passenger service passed by CALUMET I personally had the honor of getting a rare mileage trip past during an Amtrak detour over the Porter Branch after a large freight train derailment on the Chicago Line and I am glad I was able to get my own photos of the old girl while where was still someone up top bending the iron.

CALUMET, which one source lists as being built between 1895 and 1897, clearly saw a long and full life and now will probably face the fate that befalls most wooden towers of that type of either being torn down or being burnt down.  There is a slim bit of hope in that the near by GRASSELI tower, which closed in 2007 as the third to last tower with mechanically worked points in North America, was actually preserved and moved to a nearby railroad museum so who knows, perhaps the same motivated individuals are still around to get the IHB to hold back the backhoes and give this tower a new lease on life.  One thing is for sure that is CALUMET is preserved its lever frame will be vastly more interesting to play around with. Unfortunately the once tower rich IHB is down to only about two active plants on its serpentine main line after HICK closed a year or two ago up where it joined the Chicago Line.  The EJE isn't far behind although it two movable bridges with local control towers are unlikely to be put under CTC.

There is of course a Has-Been post on the closing of CALUMET, although that site doesn't seem to like direct inbound links so you might have to re-load the page or cut and paste the link and of course John Roma has been inside to take pictures.