2023 Searchlight News

 For the last post of 2023 I'm going to go through my backlog of searchlight related news items. First up is the Florida East Coast where we are all aware of the re-signaling in the Brightline Zone, but it appears that the remaining searchlights on the north end are also on the way out. The Bayard siding, just south of Jacksonville, had no evidence of signal replacement in Feb 2023, but new masts were in place by September.

Up on the former B&M Main Line east of the CSX zone in Ayer, there was been a good deal of searchlight attrition, but this has been a piecemeal process and at milepost 425 near the VT/NY state line the MP 435 searchlight was still standing as of may 2023.

East of Ayer CSX hasn't quite had enough time to start re-signaling projects as they are still trying to rebuild the connector from Warcester to Ayer. Getting out to the two searchlit interlockings between the Lowell and Fitchburg MBTA zones are high on my list.

Up on the former Montana Rail Link the searchlight replacement is ongoing with new signals up around EAST BOZEMAN.

Unfortunately around 2019-2022 many remaining searchlights on the BNSF San Bernardino Sub lost its ATSF vintage searchlights except for a few around the Riverside Station.

Finally on the UP/BNSF Joint Line south of Denver, an interesting situation has developed where CTC has been added to one of the two former single direction ABS tracks and the other has been left as ABS with no PTC due to a lack of need. This has at least temporarily saved a number of searchlights, including the mast at Milepost 226.8 just of US 85 north of Castle Rock, which has had a replacement hovering over it since 2018.

That's all for now. Remember there's no time like the present to get out and get your photos. I'll be doing a followup piece on re-signaling on the New England Central line in the CT River Valley in a few months.

The Last N&W CPL Dwarfs?

It's sometimes easy to forget that the PRR position light dwarf signal was also used by PRR ally Norfolk and Western Railway in addition to the regularly sized position lights. Their PL dwarf was even included in the 1959 N&W program to partly colorize their signals resulting in something that gave off definite UK "ground signal" vibes, albeit with the ability to display green.

Although the old N&W has been ravaged by re-signaling projects over the last decade, there are still a number of well preserved lines deep in the Appalachian coal country and Virginia. However the same cannot be said for the N&W CPL dwarf as the N&W had color light dwarf alternatives in its rulebook as early as 1961. Therefore the N&W had a multi-decade head start on replacing its PL dwarfs at the point where NS started to get involved. As of the time of this post, it has been reported that there are only 4 N&W PL dwarf signals remaining in active service at three locations. The first location is Iaeger, WV, the second Coeburn, VA and the third, with two CPL dwarfs, is Cloverdale, VA.

The Iaeger example is immediately adjacent to state route 80 just east of the Tug Fork bridge at IAEGER interlocking, just past the west end of Auville yard on the Pocahontas Division Dry Fork Branch near the village of Hull where the three track N&W position lit full crossover used to be.

The Cloverdale pair are located at the east end of the Cloverdale Branch on the Roanoke District's CLOVERDALE interlocking about 8 miles north of the Roanoke Terminal in Roanoke, VA. The first governs the end of a long industrial track that serves a concrete plant and the second serves as the exit signal for the Cloverdale siding. 

The final location is actually an automatic distant signal on the otherwise unsignaled Toms Creek Branch for COEBURN interlocking on the Pocahontas Division Clint Valley District. It is located just off Tate Ave, a few blocks from the VA state route 158 and the central business district. All three locations are in the vicinity of recent re-signaling efforts and can be considered highly endangered as a couple of other known examples, including another isolated automatic distant in North Carolina, were recently lost.

Of course rare signal types have always popped up before and I'm just reporting on the results of a forum discussion so if you are aware of an N&W CPL dwarf that has been missed please let me know in the comments! The first draft of this post actually missed the Coeburn dwarf so thank you Oakley for pointing it out.

BNSF CTC Replacing Union Pacific Julesburg Sub ABS/TWC

Just a heads up that about 24 miles of ABS/TWS (aka Rule 271) on the Union Pacific Julesburg Sub in northern Colorado is being converted to CTC as BNSF takes over maintenance of the entire Bush Sub/Julesburg Sub corridor between Union and Sterling, CO. This line represents one of those dual operating arrangements where as traffic levels dropped, two competing railroads turned their parallel lines into a single joint. In the case of the Bush and Julesburg Subs, the division point was the small railroad location of UNION.

Over the last decade or so BNSF upgraded their side of the line and, as their traffic levels increase, they gained more control and have decided to apply CTC to the Union Pacific portion of bi-directional ABS. Although Union Pacific ABS signaling had eliminated use of the pole line and installed PTC, it also made use of short mile long signal blocks with US&S N type color lights at mileposts 77, 70, 69, 67, 66 and 65 in addition to fairly uncommon late model US&S modular color lights at mileposts 71, 72, For example the CTC interlocking replacing the ABS hand throw siding end at MP 58.8 in Sterling will have its distant at the MP 61 signal location. Union Pacific appears to have already been reducing the block length with 2 mile jump to a new Safetran signal at MP 63. The project will also include new interlockings and the currently hand throw searchlit ABS siding between WE and EE MESSEX and two new intermediate signals at mileposts 79 and 78 between MESSEX and UNION. 

 

It remains to be seen if BNSF will remove/replace all of the old UP intermediates or just those directly adjacent to one of the new interlockings, but for anyone in the area all of the existing signals are easily accessible from public highways including US 6 and County Rd 178.

Results of FRA PTC Braking Algorithm Study

I recently discovered the results of the FRA's Positive Train Control Passenger Braking Algorithm Enhancement project dated September 2023. As regular readers are aware I have been a frequent critic of the overly conservative braking algorithms used by various PTC systems and vastly under perform the performance capabilities of the rail vehicles. While this FRA study was confined to the entirely wireless ETMS system used outside the northeast, it might still offer meaningful improvements to these systems in general. Long story short don't get your hopes up. In fact the results of this study might make things even worse.

So I encourage everyone to try and work their way through the linked paper (mirror here), but in my quest to add value I will provide a summary of the key points. The study examined four potential algorithm enhancements, Target Approach Management (TAM), specified consist length trains, tuned train types, and adaptive braking. TAM is for low speed (5-10mph) approach to stop signals while the other three are general purpose braking algorithms that better take into consideration various quirks of passenger train and EMU/DMU operation. The study was almost entirely carried out via computer simulation where real world variables like train consist, rail adhesion and brake pipe latency were tested in tens of thousands of combinations to estimate real world performance. There also appeared to be real world tests carried out on a test track.

The first important takeaway is that the performance baseline for defining an "undershoot", as in PTC stops the train too quickly is 500 feet for speeds under 30mph and 1200 feet for speed over 30mph. Under the baseline scenario these limits were exceeded 20-25% of the time. The PTC braking algorithms calculate a stop point probability distribution and then add a safety factor. Higher speeds mean more uncertainty so the typical stop point for 25mph might be a couple hundred feet short of the signal, the stop point for 90mph could be multiple thousands of feet short. This is why PTC forces so much aggressive braking at line speed.

As for the results of the study the good news was that the new TAM algorithm improved low speed undershoots (defined as more than 100 feet) from nearly 50% under the current proprietary EMTS implementation to a fraction of a %. Unfortunately that's all the good news you are going to get as the other "improved" general purpose algorithms blew up undershoots in the simulated runs. Specified Consist undershoots increased between 9 and 17% with some passenger train consists undershooting up to 40% of the time. Tuned Train Type saw mixed results with some equipment having less undershoots and some more. Adaptive showed no change for the commuter type equipment while undershoots for passenger type equipment went up from 20 to 30%. The gain for this drop in performance was an improvement in meeting the stop target from 98 to 99%. The real life tests resulted in a mixed bag of performance gains and losses, however unlike the costless simulations far fewer real life tests could be carried out and under much more limited conditions.

The problem with the study is that it ultimately treats a safety overlay system like autonomous operation. PTC isn't what has to stop a train before it hits something. That's the job of a skilled locomotive engineer. PTC is what should step in when the Engineer is clearly going to be doing something unsafe. Even unsafe conditions rarely lead to physical impacts at which point the crash safety system prevent potential injury or death. PTC preventable accidents of all types were already rare and PTC should eliminate at least 98% of those. Meanwhile poor train performance is pushing riders onto the roads where they'll die in car accidents. Celebrating a 1% improvement in PTC effectiveness at the cost of yet more performance isn't the win the FRA thinks it is. The infuriating part is that over on those highways self-professed self driving cars are blowing throw stop signs left and right and Federal regulators do nothing.

Caught on Camera: CSX's Gonzo Distant Signals

Distant signals, as defined as those that appear in otherwise unsignaled territory to warn train movements of an upcoming absolute signal (ie an interlocking), are seen in two flavors in the North American scene, fixed and dynamic. Many year's ago I discussed the use of dynamic distant signals on some Conrail Shared Assets lines in Southern New Jersey and although fixed distant signals are far more common, dynamic distants aren't remarkably rare. Today, most signaling systems make use of two possible distant signal rules. Approach the next signal prepared to stop and approach the next signal expecting a proceed indication of a type defined by route knowledge. As these appear in unsignaled territory neither of these conveys track occupancy information between itself and the absolute signal. CSX on the other hand defined its distant signals by a marker plate that, like the vomiting emoji, can be applied to any signal.

In practice the CSX App Marker would only be applied to Clear, Approach, Approach Limited, Approach Medium, Approach Slow and Restricted Proceed/Restricting. Basically anything that would normally appear on an automatic signal before an interlocking. Now of course this wouldn't be a "Caught on Camera" post if I didn't find an exceptional example of this system. In Cartersville, GA the unsignaled Cartersville Sub approaches the W&A sub at a wye interlocking designed BOWEN. At some point after 2012 CSX re-signaled the W&A sub and installed a new App marked distant signal right off Sugar Valley Road, seen below.

Unlike the typical dynamic distant with two lamps, yellow and green, this example has 5 lamps including a fixed yellow in the uppermost head. This was because the west apex of the wye was interlocked and could give a slow speed route and a medium speed route. Therefore the Sugar Valley Road distant can display Y/R/R Approach for a stop or restricting, Y/G/R Approach Medium for the medium speed route and Y/R/G Approach Slow for the slow speed route. Of course because it doesn't reflect track occupancy the most restrictive indication is Y/R/R Approach as seen here next to an approaching train movement. Ironically, the approach lit distant signal is indirectly reflecting the occupied nature of the block by being lit so at some level, the App Marker lies 😅.