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Tuesday, October 25, 2016

Videos from Across the Pond

I just found a few interesting videos involving UK signalboxes.  The first two involve the Banbury North Signalbox , which was recently decommissioned, but then opened for public tours (a somewhat rare occurrence due to all the health and safety BS their railways are tied up in).  Unfortunately the signalbox, like many others, is slated for eventual demolition so little other purpose than it being there.  Britain's attitude towards its decommissioned signalboxes is downright baffling seeing as every foot of railway infrastructure is publicly owned and almost everything in the UK is covered by some sort of historic preservation law.  Network Rail also seems to be chronically pressed for cash and where they can find the funds for these demolitions is beyond me.

The first video shows the full tour that was given to the public and the second video shows the view from the locking room as the levers are manipulated.  Those of your from North America should keep in mind that mechanical British signalboxes such as this, typically work on the manual block system.  Some track circuits may be provided, but train movement is primarily by manual block using block instruments instead of voice or message communications.

The third video is from Harrow On The Hill signal cabin on the London Underground in 2002 and shows a Westinghouse Style N machine, which is basically a US&S Model 14 with the levers pivoted around 90 degrees so that they throw in the traditional "back and forth" orientation, instead of left and right.  Even the tri-positionality of some of the signal levers is retained.  The most fascinating thing about this video is the use of a pneumatic assist to move levers at the far end of the frame when certain route levers are pulled in the primary operating area.  It's basically a non-vital intra-tower remote control system that doesn't require additional relay logic, a serious expense in pre and post war Briton.  This technology was later extended to create the Style V frame where all the levers were moved primarily by remote control pneumatics.

BTW, if you are wondering why the model board is all lit it, is it because that was considered safety critical information and any bulb out had to mark the track circuit as "occupied".  Of course with the bulbs burning by default I am sure there would be plenty of bulb out opportunities.

Monday, October 17, 2016

STATE Tower Closes (1937-2016)

This weekend the world lost not only an interlocking tower, not only a PRR Main Line interlocking tower, but a PRR Main L interlocking tower still sporting its origional US&S Model 14 electro-pneumatic interlocking machine.  On a personal note, STATE was the first tower I was able to talk my want into (during a long layover on the old Three Rivers while express cars were being attached) and also the first classic interlocking machine I was able to operate. 

STATE was closed due to high speed rail stimulus funds or that transportation funding deal PA worked out a few years back or some combination of the two.  STATE was the last active tower west of THORN and at times had remote control over ROY and RHEEMS, until those two were transferred to the section C dispatcher attached to CTEC.  For those of you who are unaware, STATE's opposite, HARRIS, was preserved after its closure in 1990 and now serves as a museum.  unfortunately, since STATE is an office embedded inside the Harrisburg Station it is unlikely the same sort of thing would happen, however one never knows.

Middle floor, left of the bricked up windows.
In addition to the tower being closed, STATE interlocking was substantially rationalized.  Pneumatic point machines were converted to electric, parallel paths were removed, the engine pocket spur was eliminated, the double slip switch was shipped off to Albany and #8 track was turned into a stub.

Amtrak: We don't need no extra crossovers.
PRR: One more signal is never enough

In terms of what one might consider "upgrades", the almost entirely slow speed plant traded in some of its dwarfs for high Amtrak colorized PLs supporting Limited speed movements from the main platform, although any capacity gain was wasted by placing the only set of crossovers about a half mile away from the station end of the interlocking!   For those of you familiar with the Albany terminal rationalization project, you can tell Amtrak engaged the same set of consultants.

STATE re-signaling project- 10/2015
 This project has been metastasizing for a good 3-5 years now and a lot of what they were planing was evident when I visited last year for Halloween  I guess it was bound to happen at some point and I guess I should be thankful for the extra time we had to document the plant in the digital age and I guess the new gantry and cantilever mounted CzPLs will inspire railfans for decades to come, but with so few Model 14 machines (or any non-solid state interlocking machines) left in operation

STATE and ROY machines.
I have a lot of good photos both inside of the inside and outside of STATE to stay tuned for future articles covering them.  STATE may by gone, but it will not be forgotten.

Sunday, October 2, 2016


So a while a go I posted a piece on Amtrak's OVERBROOK interlocking in the Overbrook neighborhood of Philadelphia.  Today I will be focusing on the interior and exterior of tower itself so if you missed the first port go back and read it over as I won't be reiterating any of the interlocking specific information.  Most of the interior photos were taken in 2003 and 2004, while some of the exterior photos were taken between 2011 and 2015.  Part 1 of this two part look at OVERBROOK will cover the tower's exterior, first floor and Model 14 machine on the second floor.

OVERBROOK tower was built by the PRR in 1926 and was, chronologically, in the first wave of the all-brick style of towers that would become a trademark of the PRR in its later years.  OVERBROOK was soon expanded in 1941 as part of a CTC project that gave the tower control over the remote interlockings VALLEY and JEFF (on the Schuylkill Valley Branch ), as well as having its own limits expanded with control over the west end of Belmont Yard installed as OVERBROOK's "Woodbine" section under direct wire control.

Still, compared to other PRR towers, OVERBROOK is notable for its rather diminutive size.  Similar to later 1930's towers such as WINSLOW and YORK, it still presents itself as a bit smaller, especially compared to its sister towers elsewhere on the electrified main line.

The smaller size is more apparent in the quarter view where we can see that there is only one window on each of the sides, compared with two on the WINSLOW/YORK series of towers.  One feature that reduced the footprint was the location of the air compressor plant outside the tower.

Despite its location in a big city, Amtrak was never hesitant to store spare signaling components such as PL signal targets and A-5 point machine covers, in the open, behind the tower.

Like most PRR towers, OVERBROOK is fitted with an internal staircase with a ground level entry.  The money really shows with Flemish bond brickwork with a number of decorative courses.  Also note the canopy over the door complete with slate shingles.

The PRR standard bay window takes up most of the width of the tower and today is outfitted with a number of VHF radio antennas.  Also present is the interlocking horn, which is still functional and used to clear off people crossing the tracks in the station area.

A train order lamp, consisting of a single PL-2 unit, is still mounted on the east side of the tower.  With 4 tracks and one bi-directional, there was less need for train order hooping at OVERBROOK, but it still took place from time to time.  The 80's or 90's vintage Amtrak tower sign is clearly showing its years.  Don't look for any further investment in tower aesthetics as efforts to re-signal the line loom.

Here is another view of the front of the tower, complete with a 9/11 flag, before the platform was rebuilt in 2003.

Opening the door we are immediately greeted by the sound of clockwork ticking and the smell of the 1940's as we walk right into OVERBROOK's relay room.  Normally the relay room is locked and only accessible by C&S personel, however OVERBROOK is the rare exception where the operator can also poke about in the guts of the interlocking.  In this particular bay of the relay room we can see older shelf relays off to the left and "newer" plug type relays on the right.  Note the maintainer's chair, phone and stash of spare plug relays.  This interlocking and tower is actually assigned its own full time maintainer, likely near retirement and the only person who knows how things works.

The shelf relays are attached to the 1926 portion of the interlocking, which basically means the 4-track crossover.  Unfortunately I took these pictures back in 2003 when my camera card capacity was 96 photos, or I would have taken a lot more.

Thursday, September 29, 2016

PTC and Stub End Terminals

Despite what some on the news media are saying, the PTC mandate would have not stopped the recent overrun at Hoboken Terminal, nor was it ever intended to.  The law, as drafted by congress, specified 4 things that PTC should protect against. 
  • Train to train collisions
  • Speed in excess of engineering limits
  • Workers in designated work limits
  • Open switches
Just like Stop Signal violations are not included in this list, stopping short of the end of track, or any other obstruction, is also not included on the list.  In fact, the FRA PTC regulations specifically exempt "terminal areas" from the PTC requirement, as long as the system enforced a 20mph (Restricted speed) limit in said terminal areas.  So as I said, the law, as written, and the approved PTC plans would not include terminals such as Hoboken.

Remember that Hoboken Terminal is already cab signal territory and all the trains are ATC equipped.  Despite the news reports that the train was moving at a "high rate of speed", from the condition of the cars it was likely only traveling at 10-15mph, well in accordance with the rules and the permitted speed of the track.  If PTC had been present to enforce timetable speeds, no action would have been taken.  If the end of track had been set as a positive stop point, yes, that would have stopped the train....and every other train that ever used the station, about 100-200 feet short of the end of the track because that is the safety margin that PTC systems work with.  That means every terminal station track in the country would instantly lose two car lengths.  Already overcrowded trains would need to be shorter and the net result would be more drivers dying in road accidents.

Bumper block at Hoboken dating from 1907 when a lot of rolling stock was still made of wood.

Setting aside the costs of adding PTC to complex terminal interlockings, even if you did something clever like step the timetable speed down to like 5mph, at that point you start running into issues with either slowing trains to unacceptable levels (remember the 100-200 foot buffer zones still apply) or not slowing trains enough enough to prevent a similar accident (ie safety theatre).  Why not?  Because even at 5-10mph, a modern train would blow right throw Hoboken terminal's 1907 vintage bumper posts shown above.  That's right, in this case I am pinning the blame for this accident's drama on bumper blocks that act more like a ramp to launch railcars into the roof than any sort of stopping mechanism.

Here at La Salle St station in Chicago we see a more modern setup with standard bumpers positioned in front of a deceleration zone and finally backed up by a thick concrete wall if those prove insufficient.  Other stations, especially those with high level platforms, have sufficient defenses to stop a train traveling at even the full 20mph.

Trains are not elevators.  We can't stop every accident and if we try we will only throw more and more money at ever smaller gains.  Money that could be spent on new lines and new services that can take people off the roads where over 30,000 Americans die each year.

Thursday, September 22, 2016

PRR Main Line Re-Signaling and Other News

Well I can fully confirm that the much anticipated resignaling project on the former PRR Main Line (currently NS Pittsburgh Line) has begun.  Perplexingly it has started on one of the line's newest sections located at the eastern end between CP-CANNON (exclusive) and (at least) CP-LEWIS.  As was foretold by regulatory filings NS is adopting a Rule 562 configuration by eliminating the wayside intermediate signals in favor of the already present cab signals.  The remaining wayside signals at interlockings will be equipped with 'C' boards for Rule 280a "Clear to Next Interlocking"

Replacement signaling will not spoil the view before the position lights are removed
This will see the end of a great deal of bi-directional PRR PL mast signals and a 3 track, 6-signal tubular gantry just east of CP-HAWSTONE.  As of this time the pneumatic switches are still in place at CP-PORT and CP-MIFFLIN and no new signaling has appeared from CP-CANNON eastward.  Furthermore, no replacements for the PL dwarf signals have appeared at CP-MIFFLIN. Both Conrail and NS era replacement color light signals are also being replaced at CP-PORT and CP-MIFFLIN.

Up north, CSX is finally reaching the end of its multi-year NY Central Main Line re-signaling project, with small target searchlight automatics being removed in the Batavia region where Engine 999 performed her 112mph record run.

I also just heard that the B&O CPL signals at VINE and LOCUST interlockings have also just been retired, so it looks like I wasn't quick enough getting followup shots with those.

 Elsewhere on CSX, the famous modern-mounted SCL elephant ears around Hamlet, NC continue to be whittled away.

 In a bit of interesting news, on the former Conrail Chicago Line, NS is continuing to apply Conrail blue interlocking nameplates, however they have added the 'CP' designation to the signs, which Conrail omitted, preferring just the name or milepost.

Finally, in another bit of Conrail related news, it looks like SEPTA is on its way to replacing the last Conrail era signals on its West Trenton line at CP-TRENT.  Most of this 90's vintage signaling bit the dust when SEPTA decided to separate itself from the CSX line rather than try to handle the joint running any longer.

Well that's all I have.  Remember to get your buts out there and take some pictures before, like in the case of VINE and LOCUST, it is too late.  I'm specifically referring to the PRR Main Line here.  Her out there!

Tuesday, September 13, 2016

Conflicting Route Conundrum

So the following photo drew a number of questions on both its own page and also a few of the signaling forums.  As one can see it appears that two conflicting routes have been lined over the same switch at the end of a passing siding, something that appears to indicate some sort of failure in the interlocking, or some photographic trick like multiple exposures.  The photo was taken on a Norfolk Southern line in Georgia and it's location is one reason that people are so confused.

Before I give away the answer I'll first state that the signaling logic is functioning as intended and there was been no photographic trickery.  Still, Clear and Diverging Clear appearing next to eachother in this context should be contradictory.  Here's I'm going to post another photo from a different part of the country that is a pretty big hint about what's going on here.

This was taken on the former ATSF Raton pass line where the last operational semaphores in North America are located. These semaphores are constantly being photographed, but nobody seems to be confused as to why adjacent signals can both display clear like this.  Well, there are two reasons.  The first is that there is something about Diverging Clear sitting next to a Clear at the end of a siding that just seems plain wrong.  The other reason is because the sort of signaling where this circumstance occurs is much more common out west than it is in the east.

This is your last hint before I give away the answer/
 If you haven't figured it out yet the answer to the puzzle is that the signals in both these pictures do not protect an interlocking and are not part of a CTC setup.  They are part of an ABS-TWC (aka NS Rule 271) arrangement, that also likely an example of Automatic Permissive Block .  The signals operate automatically based on occupancy of the line ahead and, more importantly for this post, trains exiting the siding do so over a spring switch so both routes through the control point are valid.

Surprise!  It's a spring switch and its also not an interlocking.
ABS-TWC / Rule 271 can actually take a couple of forms.  The first involves signals placed only on the main track so trains on the main and the siding will encounter the same signal and act accordingly.  The other places signals on both the siding and the main.  Since they are operating automatically and they 'protect" a trailing spring switch, both signals will default to a Clear indication.  Out west if there is only one possible route from a signal then the railroads don't bother with a lower head since they are happy to have route signaling handle the switch speed through the timetable.  However in the east it is standard practice to provide reduced speed movements with a  Diverging or Reduced Speed Clear signal indication.

Same situation, one less signal.
 This arrangement is not always an example of APB because APB involves an element of traffic control with absolute headblock signals that prevent trains from entering a line segment where an opposing movement is under way.  Typically the presence of absolute signals at siding exits implies APB, but this is not always the case and NS Rule 271 operation requires Track Warrants for traffic control.  In theory an APB line can operate under Rule 261 with the Conrail Southern Tier Line being one example

Well, what's enough of me rambling on.  Like I said this arrangement is far more common out west and there you don't see the Diverging aspect.  This is why it is absolutely critical to have a good understanding of how traffic control applies to various methods of signaling.  Realizing the line was running under Rule 271 with manual traffic control, it is clear how two trains could never take both routes simultaneously.

Wednesday, September 7, 2016

Letting the Air Out

Well I just completed a round trip on the NEC, paying a bit more attention to some of the signaling changes than I normally do and I have the sad duty to report that both DOCK and MIDWAY interlockings have been completely stripped of their pneumatic point machines.  This isn't any surprise as both were in the midst of years long re-signaling efforts, but at least in the case of DOCK it is a severe disappointment as it was a very high density interlocking where Amtrak has been known to preserve pneumatics. 

MIDWAY will be missed because it was a fine example of a pneumatic 4-track complete crossover, with many of the turnouts having two A-5 machines.  This leaves only HOLMES and OVERBROOK as "proper' PRR 4-track air plants. 

DOCK on the other hand needs no introduction as it is a sprawling interlocking covering the Newark Penn Station complex.  As recent as 10 years ago Amtrak had still been installing brand new A-5 point machines during a turnout renewal project.  As with the Jamaica terminal, Penn Station and 30th St, I was hoping that DOCK would win a similar exemption.

At least we had them for longer than other interlockings like MORRIS and LANDLITH, which were seemingly converted overnight.