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Wednesday, December 28, 2011

PRR Main Line Survey 2009 Part 10 (CP-RADE to CP-WEST PITT)

Well for those of you who have stayed with me on this odyssey of signaling across Pennsylvania we have reached the final leg of our Journey between Greensburg, PA and Pittsburgh itself. The daylight was beginning to fail at this point so I apologize for the decreased photographic quality.

The relevant track charts for this segment can be found here.

Beginning at Greensburg it is worthwhile mentioning an interesting feature of the right of way that important to the signaling in the area. You may have noticed in part 3.2 that SW tower at Southwest Junction had a western section where the 4-track right of way shrank to three tracks for a pair of tunnels. I mentioned that past CP-CONPIT the main line took off overland across a plateau to reach Pittsburgh directly instead of following the Conemaugh River. This resulted in a steeper grade profile as well as a number of bottlenecks in the Greensburg area in the form of tunnels. The first was located directly east of the station and was eliminated in the 1890's, the second set of tunnels hung around a lot longer and remained an operational headache.

Known as the Radebaugh tunnels after the community west of Greensburgh (which had its own tunnel) the first was built in 1852 as part of the original Main Line project and nearly derailed the entire enterprise as the cost and delays of tunneling began to give the Philadelphia area investors cold feet. The original tunnel was very tight and built on a curvy alignment through the local drainage divide between the Conemaugh and Monongahela rivers. In the 1890's a new, larger tunnel was built on a more direct alignment, at first replacing the original tunnel until traffic levels pressed the 1850's bore back into service to carry a third main track. You can see the two tunnel alignments on this Wiki Map. ... =Radebaugh

Still, three tunnel tracks on a four track line a bottleneck makes, but adding a 4th track or simply removing the tunnel never became a priority for the PRR so they did the best they could with interlocking design. Directly on each side of the new 1890's tunnel the 3 tracks shrank to 2 via a parallel shift layout with freight track 1 having the forced diverge at each. Track #4, also designated for freight, used the pimple alignment of the 1850's tunnel allowing the designated passenger tracks 2 and 3 the straight shot through.

In 1965 the waning PRR showed some of its old magic when new tunnel was daylighted in a project where the overburden was first removed and then in the space of 11 hours the tunnel roof was blasted and track re-laid with the RoW being widened over time. Track #4 remained in use through the old tunnel on the alternate alignment until the deluge from Hurricane Agnes collapsed it in 1972. The 1980 CTC project under Conrail did the rest permanently making the line two-tracks.

Anyway as I said all this was relevant to signaling as both SW tower east of the tunnels and RG tower, west of the tunnels, were built to deal with the bottleneck. Here we see the location of the new tunnel now just an open cut. In the right of the picture there is an interesting signal facing away from us for traffic on the branch line which is labeled R08. This is a distant signal to the upcoming interlocking and a vestage of the old PRR Manual Block system.

In this view taken in 2004 we see R08 in its original configuration as a PRR Position Light. This signal could display, Approach Medium, Approach and Caution. Approach Medium would display when a train coming off the branch line was had a proceed indication like Medium Clear and Approach would display if the interlocking was showing a Stop indication. Both would show that the track circuited approach block was clear, however if it was not the signal would display a Caution signal which on a PRR PL is \ over a marker light as shown in this photo.

Saturday, December 24, 2011

PHOTOS: Amtrak THORN Tower

Those of you who read my earlier essays on the signaling of the PRR Main Line might remember a bit about THORN tower in Thorndale, PA (where else!). Situated at the junction of the original PRR Main Line and the Low Grade Extension of the Trenton Cutoff, THORN interlocking proper consisted of a 6-track full crossover with the two track Low Grade Extension to the east and a small yard and helper base to the west, both sandwiched in between the two main tracks of the Main Line. Today THORN tower remains active as part of Amtrak's Harrisburg Line having seen many changes over its 70 years in operation.

THORN tower was built in 1938 and at the time it represented a bold form if new technology on the traditionalist Pennsylvania Railroad. The PRR had been a strong proponent of the traditional block system with Block and Interlocking Stations spaced even intervals along the line with Block Operators passing trains from one to another. As the PRR was a wealthy railroad and could afford the expense of building interlocking plants where many other railroads would make do with hand throw switches and the Automatic Block System. As the cost of technology began to drop in relation to labor Centralized Traffic Control began to be embraced by PRR rivals such as New York Central. Intended to replace train orders on long single-track lines, CTC pulse-code technology could nevertheless allow multiple interlockings of any configuration to be worked from a single location. While the PRR would continue to rely on the individual Block Station until the end, it did install several significant CTC projects with THORN being one of them.

THORN's territory stretched from MP 25.3 to MP 36.6 on the Main Line and also included the Philadelphia and Trenton Low Grade Extension between those two points as well. In addition to its own namesake interlocking, THORN had CTC control over DOWNS, GLEN and DALE interlockings to the east and CALN interlocking to the west. While today CTC implies bi-directional operation, the PRR was content to use the technology for simple remote control and most of the routes were left operating under single direction ABS.

The Penn Central era brought some minor reductions to THORN's plant with the Low Grade extension being reduced to a single bi-directional track and the line between GLEN and PAOLI being reduced from 4 tracks to 3, with the center track being bi-directional.

Under Amtrak the plant shrank further with the Low Grade Extension being completely abandoned, the Thorndale yard being almost completely removed and the 3rd track between GLEN and PAOLI being ripped out due to the loss of through freight service on the Main Line in the early 1980's. However most of the interlocking layouts were kept the same due to the costs involved with modifying the logic. Here is how the territory looked in 1992.

In 1994 the closure of Paoli Shoppes due to massive PCB comtamination forced SEPTA to build a new terminal Yard in Frazer, PA for its popular R5 commuter service. This added a simple interlocking for trains to enter/exit the yard and to turn back just east of GLEN intelrocking. The old DALE interlocking, now little more than a Control Point was eliminated and the few local freight accessing the Main Line would queue up at the home signal at GLEN.

While even more changes are planned for the Harrisburg Line, in 2010 THORN and its territory are much the same as they were in 2005 when I was able to commission a survey of the tower and its interlocking plant. Some of the photos had to sit on ice for a few years, but they have been recently processed and posted for you all to enjoy. Photos that were releasable at the time were processed at a lower resolution due to the conventions of screen sizes and internet connectivity at the time.

THORN tower is an identical twin to the previously discussed COLA tower, which like THORN was a PRR CTC tower built in 1937. Both these towers were built in conjunction with the electrification of the PRR Main and Low Grade freight lines to Harrisburg. It is a two story brick building with no trademark bay window. It could be considered a forerunner of the 1940's towers built up and down the Northeast Corridor and discussed in the overseas section. The tower has a number of subtle art deco flourishes as well as a pair of interlocking illumination floodlights (one currently active). Also on the right side of the tower note the tower emergency horn which, in theory, can be used to stop trains moving through the plant.

Thursday, December 22, 2011

Good News From Down Under

Actually its not Australia I'm talking about today, but New Zealand.  Recently I had heard that a re-signaling scheme had been carried out on the Hutt Valley Line, the old signals of which actually had their own website.  Well today I learned that the project only re-directed CTC control from a local US&S panel to a dispatch office in Wellington.  Even better all the original relay based CTC interlockings were left untouched.

Ok, that's pretty minor, but the news gets better.  While the US&S Model 14 interlocking machines in the US are marching towards extinction with the recent re-signaling projects at ALTO, UNION and WB, US&S parent company Westinghouse did sell power frames based on that same technology overseas to mostly British commonwealth countries as the style L, K, N and B miniature lever frames. They are basically US&S frames just with the levers working back and forth instead of side to side (so the poor signalmen wouldn't get confused ;-) )  Anyway these are about as rare as their breathern here in the United States with only a handful of examples still in main line operation in the UK and South Africa.  Well today I learned that again, despite some minor re-signaling, not only is the large Style L frame controlling the Wellington, NZ terminal still in service, but it was actually upgraded with three flat panel displays replacing its old bulb lit model board.  Talk about a clash of technologies!!

Not only does that frame survive, but so do three others on the North Island Main Trunk at Tawa, Porirua and Plimmerton with Porirua being in use daily and only Tawa being "generally known" about.  Here is a page that has some more up to date information on the Style L machines in New Zealand.

Anyway its nice to know that even if power frames vanish from the United States they can still be found in some nice vacation destinations overseas.  And then if those go you can always check out the pneumatically actuated Style V machines installed on London Transport up through 1999!!  

Monday, December 12, 2011

Wee Bit of Good Searchlight News

Just saw that out on the former Southern Pacific line in Mojave, CA the MP 377 signal bridge is being taken down for what are probably justified structural issues.  However the two track gantry with its 4 searchlight signals is being replaced with a pair of searchlight masts.  Huzzah!!  Finally, a Class 1 railroad that isn't afraid to Reduce, Reuse and/or Recycle.



The searchlight masts definitely appear to be used, but hey, I'll take it.

Sunday, December 11, 2011

C&O Main Line Re-Signaling Plan

Well the bad news is in and if you have plans to ride the Cardinal do it now because most of the remaining C&O signaling on the main line will be gone by the end of next year.  Already the signaling has been moving east from Montgomery, but I just learned that already the old signals have been removed between OX Cabin and Clifton Forge on the east slope of the Allegheny slope.  Next year the plan is to fully denude everything between there and Hinton including White Sulfur Springs and the summit at Tuckahoe.  Hopefully there will be something left when I ride the dome car on the Cardinal next season .  I'm feeling really bad that I didn't seize the opportunity this year, although I do have two surveys of the signaling on the line of marginal quality.

Saturday, December 10, 2011

PRR Main Line Survey 2009 Part 9 (CP-JW to SW)

As we enter the final zone of signaling on the PRR Main Line I thought it might be worthwhile to summarize things a little in relation to where the signaling in each section dates from and who installed it as we travel from Philadelphia to Pittsburgh to provide a bit of perspective.

  • MP 000 -> MP 067 - Pennsylvania Railroad - Relay + Electromechanical - 1940s
  • MP 067 -> MP 104 - Amtrak - Solid State - 2008
  • MP 105 -> MP 231 - Conrail - Solid State (GE Series 6) + Relay - 1990
  • MP 231 -> MP 237 - Pennsylvania Railroad - Relay (US&S 504 CTC) + Electromechanical - 1950s
  • MP 237 -> MP 265 - Conrail - Solid State (GE Series 6) + Relay - 1994
  • MP 265 -> MP 274 - Norfolk Southern - Solid State - 2000
  • MP 274 -> MP 290 - Conrail - Relay (no interlockings) - 1990
  • MP 290 -> MP 353 - Conrail - Relay(? Listed as D601 system) - 1980

Not sure what conclusions can really be drawn here, but as we pass Johnstown we enter into the earliest of the re-signaling projects that was intended to replace the original PRR signaling. The Pittsburgh Division interlocking charts indexed at Multimodal Ways list the interlocking system used in this section as D601 (details of which I was unable to locate) and the interlocking sheets are the last series of which were hand drafted. I suspect this is a late model of all-relay based CTC technology that first became popular in the 1950's and was eventually supplanted by the new SSI systems in the 1980's.

One side effect of being an early adopter was that none of the PRR signal bridges were replaced with Position Light mast signals. In 1980 railroads still had many first generation road switchers in service and they were designed to run long-hood forward so signals still had to be mounted to the right of the track (Engineer's Side). This meant either gantries or tall bracket masts were needed on double track CTC lines. The downside of this is that between MP 290 and MP 353 there has been significant attrition of position lights because by the time the gantries finally became life expired Conrail has stopped installing position light mast signals to replace gantries like they had between MP 105 and MP 231.

We begin our journey at Johnstown on a new track diagram, but still in three track territory.

Past CP-C we come to CP-JW, which used to be remote C tower with direct wire control from C's Model 14 machine. CP-JW was re-signaled when C tower was closed and had all new signals installed. Like CP-AO, CP-JW is on track 1 only and provides access to the Johnstown yard and helper base from the west. As such there is a power split point derail on the yard track. The signal on the main track is an innovative model that allows the whole signal head unit to be cranked down to ground level for servicing. While this saves on maintainers having to climb the ladder, it requires that the signal be taken out of service, a complicated process that involves the dispatcher and transmitting paperwork to trains. Simply working on a traditional signal will simply result in a dark head, which is covered by standard rules. The yard track has a simple 3-stack Safetran modular dwarf signal that can display 1 or 2 lamp combinations.

I should mention here that when Conrail re-signaled the lines it was more likely to connect the existing interlocking appliances and signals to the new vital logic controllers. Today most railroads prefer to install brand new signals and get all the testing out of the way before taking the old signals out of service and placing the new ones in service in one go. In a literal cut-over the interlocking would have extended downtime to test all of the splices were done properly. CP-C and CP-JW were both re-signaled in this new fashion.

The new relay hut was placed directly adjacent to the old one. It looks like in 2003 someone was still producing new Conrail style ID boards.

A traditional mast signal was erected at the west end of the interlocking in the new NS "tombstone" variety. The switch at CP-JW leads to unsignaled territory, but CP-JW is also the track 1 distant to CP-C and grants a lower head green lamp for Approach Medium aspects.

Just past the Johnstown Amtrak station we pass the 2752E signal mounted on a late model PRR gantry. The position light signals on this bridge apply to track 2 only and it is the eastbound distant to CP-C on track 2. This section of the line had its block signals refreshed by Conrail in the 1990's so their style of re-numbering applies. I should also point out that while this looks like a normal three track line, track three on the left is not like the others. It will diverge from tracks 1 and 2 and cross the Conemaugh River to run down the other side to CP-CONPIT. Singles lines with tracks that take different paths from point A to point B is not a unique occurrence and such routes are often called Slow Routes or Turkey Paths. In this case the time penalty for a track 3 routing is 15 minutes and every so often this train suffers the hit then tracks 1 and 2 develop blockages.

Also note where the second island platform for the Johnstown station used to sit.

Tuesday, December 6, 2011

Speed Signaling with Caltrain

Between 2002 and 2004 the Caltrain commuter route on the peninsula between San Francisco and San Jose underwent a near total rebuild to bring it up to the same high tech standards as many of the companies that had their headquarters adjacent to its tracks. At the turn of the 21st century the line was operating much as it would have been at the turn of the 20th with basic single-direction Automatic Block Signal operation with hand operated crossovers at temporary block stations where orders would have hooped up to trains during single line working. Much of the line still used jointed rail and there were only five interlockings on the entire route clustered at the north end near San Francisco, one of which was the 4th and King St terminal and the three of the remainder being used by freight trains accessing spur tracks.

Fortunately for history the line was documented by a West Coast signal fan and you can see his work here.

Two years later the line could not be more different. It was upgraded to fully bi-directional CTC operation with welded rail and large sections with concrete ties. Stations were rebuilt and two long 4-track passing sections were constructed near the Northern and Southern portions of the line to allow new express train services to pass locals without delay. A plethora of new interlockings were installed to allow 2-track express passing or just easy recovery from engineering works. Again, all of these changes were documented by the same signal fan.

What is perhaps more interesting is that as Caltrain owned the tracks between CP-COAST and San Francisco it was free to make the decision to abandon the old Southern Pacific inherited 'route' signal rules and adopt more modern speed signal rules comparable to those seen in the east. As Amtrak had the long term contract to run the Caltrain services this better fit its operating practices elsewhere in the country.

The old route style signaling had been popular back when interlockings were few and far between and traffic densities light, but with increased routes and higher speed differentials Caltrain dumped the whole route concept and adopted a speed signaling scheme influenced by prior art, but with its own unique flavour.

The Caltrain signal rules can be found its the following rulebook documents. Also included are the Union Pacific route signaling rules still in service on the UP owned portions of track so you can compare and contrast.

Caltrain ETT No 2
Caltrain ETT No 2 Supplement No 4

So what is interesting is that Caltrain started with the typical "Northeast" style signal set with Y/Y as Approach Slow and *Y* as Advance Approach, but dumped the use of "bottom yellow" in Restricting signals, using *R* instead. With bottom yellows now free R/Y and R/R/Y could be tasked to Medium and Slow Approach. The system retains some Western influences with the Approach Restricting aspect and Caltrain also added some innovative new aspects such as R/*Y* as Limited Advance Approach, R/R/*Y* as Slow Advance Approach and R/Y/*R* as Medium Approach Restricting. They also logically extended the Northeast style system by using R/Y/Y as Medium Approach Slow.

Because no automatic signal aspect requires 3 heads (a problem caused by using Y/R/G for Approach Slow) Caltrain was able to adopt a uniform visual aesthetic for its signals (probably to the delight of its vendor, US&S) by fitting all standard block signals with 1 head, distant signals with 2 heads and interlocking signals with 3 heads. Each head in turn was fitted with all three lamps, if they were needed or not. This gives the engineer an easy way of identifying what sort of signal they are facing, even if it means Caltrain spent a lot more outfitting signal lamps that would never need to be illuminated. On some of the 4+ track home signal gantries this can lead to quite the interesting Christmas Tree effect, especially when flashing aspects are involved.

This brings us to our main feature. Back in March I was out in the Bay Area for a conference and I was able to capture video from the north-facing railfan window of a gallery car of the entire line. Now this consists of about 40 minutes worth of video showing nothing but Clear signals and is probably something you don't really need to see, however I later filmed a second partial run at night where my express train takes the Bayshore passing route for some reason which shows off some aspects other than Clear. Also in evidence are the numerous grade crossings (including pedestrian grade crossings at stations which the trains have to whistle for) and this really cool Southern Pacific era 8-track signal gantry that was fitted with new signals and left in place. In that same area you can also see the last hand operated crossovers on the line used by local freight trains to switch between goods sidings that straddle the main line.

The first video between Millbrae and Bayshore can be seen here:

There is a gap between the way caused by my camera batteries running out.

In the second video you can see the new Lunar White marker lights that were attached to the signals in the terminal area for some reason. The terminal is the only un-resignaled portion of the line retaining its original Southern Pacific searchlights and pneumatic point machines (possibly the only pneumatic points west of Kansas City) and the Lunar Markers may be to differentiate the special case terminal signals with the new speed signaling system.

Anyway, I hope you all enjoy the video and see that converting to Speed Signaling is an achievable goal.

Monday, December 5, 2011

Finding a Blue Lining

We all know the railroads have been in overdrive lately resignaling even perfectly functional interlockings on non-pole line CTC routes.  Well I have managed to find one small silver, or should I say blue lining to all of this.  Recently NS re-signaled three interlockings on the western end of the Conemaugh Line near Pittsburgh.  CP-HERR, CP-ENTA and CP-SHARP were all Penn Central era interlockings with mostly solid steel signal gantries and cantilevers, position lights and pneumatic point machines.  Well NS removed the whole lot as they reconfigured Enta Yard.  However at both rebuilt interlockings NS bothered to install brand new Conrail blue location signs on the relay huts.  I guess its a nice thought, but I would have preferred they leave the interlocking appliances alone to begin with.

Here we see the original relay hut with the new cantilever mast.

And the new relay hut with the new sign.