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Saturday, June 29, 2013

The New Interlocking Towers?

It is a bit ironic that the same automation technology that so utterly decimated traditional interlocking control systems now seems to be reviving things in a way.  As the cost of automation continues to drop what used to be handled by hand operated switches can be remote controlled using less formal methods. Here are a few photos I spotted of a new remote control yard operation at Camden's Pavonia Yard, which was recently downgraded from a humped classification yard to a flat remote control job.

Here we see the "tower" (pavilion?) in the middle of the yard leads.



The magic happens on a ruggedized touch screen panel that allows the remote control engine operator to also remotely operate the yard switches.



Here is the actual interface.  As you can see it also include authentication (probably hard coded to some easy to guess password) and various functions to both throw the switches and possibly remote control the engine or functions of flat switching.  Doesn't have the charm of a real interlocking tower, but its not hard to envision this sort of thing moving to a mobile device and out of yards and onto non-signaled branch lines.



Monday, June 24, 2013

Signaling Marches On

I have a few more signaling updates to go over.  First up the N&W colorized position lights at Marion, OH have finally been replaced by the generic Darth Vader cantilevers hovering over them.


As is typical there was no improvement of actual rail operations as the new signals still cannot display a restricting indication under NS-N&W signal rules.


Next up is the sprawling Chicago, Burlington and Quincy  complex at Galesburg, IL.  I was lucky enough to have passed through there last year on the California Zephyr and got a full set of pics.  Was hoping to get another round of photos this year, but it was not to be as the new signals were just recently cut over.


 On the former Grand Trunk line in Michigan, Canadian National is starting to go after even their modern type searchlight installations with LED Darth Vaders...again with no Restricting capability.



 Finally the last 2 B&O color position light locations were expunged from the Metropolitan Sub.  These included the intermediate signals at High Rock and the EAST BRUNSWICK interlocking.  Both were fully modern installs from the 1990's and were nowhere near the ends of their useful lives, but CSX got some government $$ to upgrade the line for MARC service so why not spend spend spend.  I did manage to fully document the autos at High Rock, but I only bagged half the plant at EAST BRUNSWICK with a followup trip planned for this summer.  Looks like I'll have some additional free time :-(  You can see the photos I did manage to take here.


Sunday, June 16, 2013

PHOTOS: Brighton Park Crossing

Brighton Park Crossing appears on collections of interlocking charts, but it isn't an interlocking. It appears on lists of Chicago Rail Junctions, but it's not really a Junction either. What it was was a mess, a throwback to a time when railroading was a confusing and messy affair, a piece of living history that became a somewhat sanitized museum before vanishing into our rapidly homogenizing rail environment. Now largely remembered as unique, Brighton Park during its heyday wasn't anything special, especially in the Chicago area, but it still represents an important case study not on the history of railroad signaling and how it developed in North America.


 For those of you who don't know, Brighton Park Crossing was a non-interlocking railroad crossing at grade between the compass east-west Chicago and Alton main line, and the three parallel compass north-south main lines of the New York Central – Chicago Junction, Baltimore and Ohio Chicago Terminal and Pennsylvania Railroad Panhandle Route. There were 8 tracks crossing 2 tracks that gave the plant a total of 16 diamonds with three wye legs and a number of crossovers thrown in to boot. The obvious question is of course, how did this complex crossing between three of the richest railroads in the country stay a non-interlocked manual operation during an era when the same railroads could and did afford to make something better at other similar locations in the region. Now of course I haven't been able to turn up the exact decision making process that lead to Brighton Park's ultimate configuration, but we are in a position to make a few good guesses.

The first, and perhaps foremost reason, was that this was simply not a priority route into Chicago. For the New York Central and PRR, this was not used by the streamliners making their grand entrance into Chicago from New York, but instead something more like the service entrance used by delivery vehicles. For the NYC all this route did was act a way to interchange freight with "western" roads. For the PRR the situation was essentially the same except for a smattering of passenger trains using the "back door" at Union Station to reach such thrilling destination as Indianapolis and Cincinnati. Only for the B&O was this their primary route into a downtown passenger terminal, but the B&O had long since given up trying to compete on time with its larger rivals, instead focusing on luxury. While the crossing did affect the Alton main line, the Alton was the priority user with the Pennsylvania Railroad being responsible for maintaining the crossing protection as the Panhandle railroad was built after the Alton. However being first is not always an advantage as whatever agreement was struck with the PRR would remain in effect even if conditions later changed. If the Alton had signed off on a non-interlocked crossing and did not wish to renegotiate then a non-interlocked crossing it would stay.

As you can see Brighton Park was not the B&OCT's biggest problem in reaching downtown Chicago in a timely fashion.
The second reason is the simple fact that interlocking technology was still very expensive back in the day and a similar interlocking plant at the 4x4 75th St interlocking (aka Belt Crossing) required a 132 lever mechanical frame that was not retired until the late 1990's. Making matters worse is that diamond crossings are notoriously tricky to signal properly because you cannot use traditional track circuits over a long string of diamonds. Because diamonds are already impractical to incorporate into track circuited rail single diamonds are simply excluded from the circuit. However multiple diamonds can potentially allow cars to "hide" in the dead section so in that case a construct called a "trap circuit" must be used. This works sort of like an axle counter before such things existed and basically makes sure that a diamond is marked as "occupied" as long as the train that tripped the circuit on one side of the diamond, also trips the circuit on the other side, in sequence. Multiply the logic over 16 diamonds and 10 tracks in both directions and you have quite the headache. Furthermore Brighton Park did not stand in isolation. Similar crossings existed at Ash St (8x4), 26th St (8x1) and 12th St (7x2 + 2x5) and all would have needed to have been interlocked to realize any of the benefits. Finally, speeds on the north-south trunks were only about 20-30 mph, so having to stop and proceed at crossings did not add significantly to the schedule.

The third reason is a bit softer, but one that I believe is still a strong unconscious motivator to preserve a status quo. If Brighton Park were to be interlocked, it would become more susceptible to policy capture and with the PRR pulling the levers the other railroads preferred leaving routing decisions in the hands of low level employees instead of higher level managers. Because it was not an interlocking Brighton Park was worked by switchtenders, which is even lower on the totem pole than a tower operator. They would be out and about, in full view of the crews and even switchtenders from other railroads. In the absence of some high priority passenger train there would be strong social pressure to be as fair as possible with regard to which train was allowed through the diamonds.


So lets take a look at Brighton Park as it was in its heyday before looking at what it eventually became.  Before it was retired Brighton Park was known for its switchtender's shanty, 10 diamonds and that semaphore bracket.  Back in the day however there was not one but two primary tender shanties, four semaphore locations and and three additional tender shanties.  Of all the manual crossings on the Panhandle trunk Brighton Park was easily the most complex in terms of the train control apparatus and this was mostly because this wasn't just a simple crossing like Ash Street, but actually had some switches that needed tending.  These consisted of two western wye connections between the B&OCT and the Alton, a southeastern wye connection from the NYC to the Alton and a twin pair of facing crossovers between the Panhandle and the B&OCT.  Operation of each of these crossovers was assigned to a specific switchtender with the Alton, PRR, B&O and NYC all employing tenders at Brighton Park to throw their assigned switches.  The diagram above actually marks which switches were assigned to which tender.


Of course the mechanically operated semaphores at Brighton Park became its most iconic feature.  At the time of its closure there were 8 signals still in operation, 5 on the central bracket mast and 3 on a secondary mast in the northwest corner of the crossing.  These were directly operated from an 8 lever S&F mechanical frame via pipelines.  The system was simple.  When it was time for a train to proceed across the crossing the switchtender would raise the semaphore corresponding to the line and direction.  The B&O, PRR, NYC and Alton each had 1 semaphore for each timetable direction for a total of 8.  The B&O, Panhandle and Northbound Alton signals were mounted on the bracket, NYC and southbound Alton on the single mast.  After Conrail abandoned the PRR Panhandle main line, a single ex-PRR running track was left in place for industrial work and it inherited the Panhandle semaphores. The lever frame provided basic mechanical locking to prevent conflicting movements from being routes (ie Alton xor anything else). Check out Jon Roma's Flickr page for additional photos of the semaphores and pipeline system.


I mentioned before that the B&OCT had wye connections with the Alton.  As you can see, with the Panhandle route standing in between the B&OCT and the Alton something had to be done.  This came in the form of two additional semaphore signals which would protect the diamond crossings of each wye track with the Panhandle main line.  The south wye was protected by an additional 4 semaphores worked from a 4 lever mechanical frame at the opposite end of the "A" tender Shanty.  The north wye was protected by a similar set of 4 semaphores, this time worked by a miniature lever frame next to the mast outside of the "B" tender shanty.


Since the 1940's and the resulting contraction of rail traffic, Brighton Park has been rationalized into the form we know it today.  You can find a complete rundown of the current state of Brighton Park on its own Chicago Rail Junctions page, but in summary, the former PRR Panhandle main line was completely ripped out leaving just the single industrial track behind with Conrail shifting traffic to the former New York Central line.  The B&OCT dropped its wye connections to the Alton as that route decreased in importance and other interchange points became available.  This reduced the number of diamonds to 10 in a 2x5 configuration.  Without the wye tracks all the many switchtender positions and tender shanties were eliminated including the PRR "B" shanty and the two semaphore masts protecting the wye tracks.  This left behind the "A" shanty and the 8 semaphore signals guarding the Alton crossing itself.


Like i said before Brighton Park isn't an interlocking and without the need to either house relays and electronics or keep them dry, the operating environment is rather minimalist.  There is a door, some windows, an air conditioning unit and an external portable toilet.  Even calling this a "cabin" would be generous and just about the only thing Brighton Park  has in common with an interlocking tower is "Tower Window Syndrome".  In this view you can see the pipelines emerging from the shanty's lever frame and passing through a set of cranks before running out to the two masts.

Sunday, June 9, 2013

Hancock Tower Inside Tour Re-posted

One of the first posts in this blog featured the former CSX / B&O HANCOCK tower located in Hancock, WV.  I had taken a large number of interior photos shortly before it was closed and demolished in 2007, but the writeup first appeared on a web forum that did not accept embedded images.  Therefore I re-wrote the piece to use links instead of images and that's what was posted here.

Well I have some good news in that I went back through and restored the photos in addition to a few other small edits.  For anyone who might not have ever seen the page on HANCOCK or those who saw it in its mostly text form I invite you all to take a second look.

http://position-light.blogspot.com/2011/05/inside-hancock-tower.html


Tuesday, June 4, 2013

Know Your Cab Signal Displays!

North America has two dominant cab signaling technologies and by two I mean one that is dominant and another one that is still used. The first is the pulse code cab signaling system based on the system originally invented for the Pennsylvania Railroad and the other is the two aspect system used on some former Chicago Northwestern lines sometimes referred to as Automatic Train Control. While in the case of the former there are a few variations pertaining to the number and type of cab signal codes, the real diversity comes in the form of how the cab signals are presented to the train crew which contrasts with wayside signals that are becoming increasing homogeneous. As cab signal displays are usually installed under the purview of the railcar vendor as opposed to railroad signaling departments there is even a large amount of diversity between different batches of locomotives. So today I will tackle the task of helping you know your cab signal displays.

The first model we will examine is known as "The Classic" and was what was most commonly fitted in locomotive cabs before the widespread use of plastic. These were generally installed new up until the 1980's and were most commonly found in Conrail locomotives although other small time users of cab signaling like the Rock Island and its successors. Classic style displays were mounted on the central pillar of the front windshield and consisted of two faces visible from both sides of the cab each with 5 display targets capable of showing 4 indications. The display was rather large and beefy due to the light bulbs used to illuminate the display targets. True to their name, classic displays displayed actual cab signals, hence why one would see miniature position or color lights. Typically used without speed control these cab signals gave the crew a rough idea about the line ahead and the last wayside signal they passed. Non-PRR lines often used 4 color light displays instead of 5 position light displays and there were classic versions of the two aspect system used on the CNW, IC and some other railroads. Here we see a classic style display mounted in a Conrail Geep.


Starting in the 1980's advances in miniaturization lead to what I like to call "The Compact", which became popular with Conrail, Amtrak and more recently Norfolk Southern. Effectively the same design as "The Classic" and mounted in the same location, "The Compact" uses smaller light bulbs or LED's to illuminate the same 4-indication, 5 head display. This photo shows a brand new Compact model display mounted in a newly rebuilt NS SD60E.


 Meanwhile, further west, the Union Pacific embarked on a project to equip hundreds of miles of its main line between Chicago and Wyoming with what it terms Automatic Cab Signals, but functions in the same manner as NORAC's Cab Signaling System. UP successfully mapped its color light route signaling scheme onto the 4 indication cab signal model, but its legacy 2-indication "ATC" system inherited from the Chicago Northwestern provided a bit of a rub and prevented UP from adopting its own color light version of "The Compact". What resulted was what I like to term "The Combined", a combination 4-indication ACS display and a 2-indication ATC display. Now, why didn't they just use the 4 indication display to also show the 2 indications used by the CNW. After all in theory it has two indications to spare. That is because ATC isn't joking when it says automatic train "control" and the way the system gets away with two indications is the use of speed target timers that require the train to reduce speed to Restricted within a certain period of time. ACS and ATC were integrated into a single box, but retained different displays to help the crew remember what system they were operating under. Here we see a Combination type display centrally mounted in  the cab of SD70M #4450.


 For a better look at the old 2-aspect ATC display here is one in a cab of a retired METRA E unit at the Illinois Railway Museum.  Mounted on the center pillar can be seen the R/Y "Restricting" indication and the single G "Clear" indication.  The white light may be an overspeed indicator or a ATC territory indicator.


 Automatically controlling train speed through cab signal indication is a natural extension of any cab signal system and the technology has been available since at least the 1950's in passenger locomotives using electromechanical systems with relays and air valves. When commuter rail operator SEPTA wanted to update the cab and speed control system in the cabs of its MU fleet, the result was a more advanced display that did away with the 5 individual position light displays and instead replaced with two multi-aspect heads. Unlike the other displays we have seen, these integrate the speedometer and cab signaling function into one integrated display since that information is also used by the electronics inside the display to handle the speed control system. For signaling the upper display shows | For Clear and / for Approach and Approach Medium while the bottom display shows the | part of Approach Medium and a \ for Restricting. Here we see a Two Head display mounted in a SEPTA Silverliner IV.