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I know this update is a long time coming, and for that I apologize :)

Alright… first up in our ‘Methods of Control’ discussion is the Occupancy Control System, or OCS…. or ‘dark territory’…. or a way of running trains without signals.

OCS is called dark territory for several reasons. First of all, as opposed to Centralized Traffic Control (CTC), the dispatcher cannot immediately see where the trains are, or directly control where they are going by ways of remotely controlled switches or signal.

As we learned in the previous section, you need to engineer a means of having oncoming trains pass each other, because double tracking a line can either be expensive or impractical. Now that we’ve got our line installed with sidings, it’s time to decide who goes ‘in the hole’, and who gets to continue on their way.

OCS works on a principle of ‘clearances’ – in that the Rail Traffic Controller grants permission for a train to travel on the line, from point A to point B – point B meaning a meet with another train somewhere down the line.

Let’s say we’ve got two trains departing from Zipperville and Alphaville around the same time. At some point, one of these trains has to pass the other in order to make it to their destination. In our previous section, we discovered that sidings exist as ‘passing lanes’, in order to allow trains to pass each other on the main line. At the railway’s office, the dispatcher’s job is to determine where and how these trains are going to meet.

In OCS territory, this is accomplished with ‘clearances’. The dispatcher will build a plan for the line, determining when each train will meet, and how it will happen. After formulating this plan, he will put it into action by giving clearances that make this plan happen.

Train 1 is departing Alphaville, and is 2000 feet long. Train 2 is departing Zipperville, and is 1800 feet long. A dispatcher uses a wide variety of information to formulate his plan, including the size, weight, locomotive type, the weather and priority of the train in order to plan his meets. This is all required because he needs to roughly know how long it takes for at train to travel the line in order to make each meet as efficient as possible.

The roadmaster has told the dispatcher that Train 2 is carrying some very important cargo for Alphaville, and needs to get there as fast as possible. Right away, the dispatcher knows that Train 1 is going to be the one that is going ‘in the hole’ in order to let train 2 proceed without stopping. But…. where should this meet take place? All things being equal, Middlesburg is directly in the middle of the rail line. If both trains left their respective stations at the same time, and travelled at the same speed, then the meet would obviously take place at Middlesburg siding. However, it’s up to the dispatcher to determine if this is practical. If train 1 is going to be travelling slower, or if it’s a passenger train that will be making many stops, his plan needs to reflect this. Maybe the trains will meet at Southton, instead… or maybe Northton?

For the sake of simplicity, let’s say both trains depart at the same time, and will be travelling at the same speed. So, they will be meeting at Middlesburg. Now, it’s time for the dispatcher to issue clearances to the trains so they can depart.

Train 1’s clearance would be something like this:

Clearance number 1 to Conductor Smith on Train 1 North. Train 1 North may proceed from Station Name Sign Alphaville to the south siding switch Middlesburg, and clear the main track.

Train 2’s clearance would be:

Clearance number 2 to Conductor Jones on Train 2 South. Train 2 South may proceed from Station Name Sign Zipperville to the south siding switch Middlesburg.

Each train has permission to depart, and has instructions on what to do when they get to Middlesburg. Train 1 North will, once arriving at the South Siding Switch Middlesburg, leave the main track and enter the siding. The train will stop, the conductor will get out of the locomotive, and physically throw the switch for the train to enter the siding. The conductor can get back on the train at this point, because the position of switches (and warnings to crew who may encounter reversed switches) are part of OCS clearances. For example, if a previous meet at Northton meant that the north siding switch was reversed, the dispatcher will include that as part of their clearance.

North Siding Switch Northton may be in reverse position

Would be included in the clearance. This means the train, when encountering the switch, would have to get out and manually normal the switch before proceeding. Obviously, this is important! Rule card carrying employees (such as other train crews, maintenance workers, etc.) if they encounter a reversed switch out on the line while working or passing through, will often stop and reverse the switch as a courtesy to the dispatcher and the crews. Once done, the crew member reversing the switch will contact the dispatcher and file a switch normal report with them, so future crews won’t need to worry about the switch.

So, if all goes to plan, the meet will go off like this:

- Train 1 will arrive at the South Siding Switch Middlesburg, throw the switch and enter the siding to wait for train 2, pulling up to the north end of the siding.
- Train 2 will arrive at Middlesburg, and slow down to stop at the South Siding Switch Middlesburg, the end of their clearance

Both trains have met the requirements of their clearances, and cannot move any farther. Obviously, this is no way to run a railway, so the dispatcher will have given new clearances to each train while they are en route to Middlesburg. Train 1’s clearance would have been:

Clearance number 3 to Conductor Smith on Train 1 North. Train 1 North may proceed from North Siding Switch Middleton to Station Name Sign Zipperville. Train 1 North may not proceed until Train 2 South has passed North Siding Switch Middleton.

And Train 2:

Clearance number 4 to Conductor Jones on Train 2 South. Train 2 South may proceed from South Siding Switch Middleton to Station Name Sign Alphaville. South Siding Switch Middleton may be in reverse position.

That ends their journey – through a careful set of OCS clearances, both trains were able to safely and quickly be on their way with as few interruptions as possible. OCS clearances can contain other information, such as protection of work limits track work, provisions for two trains to follow each other, and performing switching on the main line.

There are several limitations to OCS – while the dispatcher will have a rough idea of where each train MIGHT be, based on the limits of their last clearance, there is no way for the dispatcher to check on a train’s progress without physically asking them. This creates issues when there are several trains operating on a piece of track, and a train has a particularly long clearance (A clearance from Middleton to Alphaville encompasses half of the line!) A train will, either out of courtesy or if asked by the dispatcher, to give a ‘track release’. This is a report that a train has cleared a certain landmark or location, essentially ‘giving back’ the track to the dispatcher. For example, let’s say that Train 3 North sitting in the  siding at Northton – the dispatcher cannot issue a clearance over track that he’s already given to the southbound Train 2, so he will ask Train 2 to give a Track Release once he’s past the North Siding Switch Northton. Once the train has passed the North Siding Switch at Northton, he will contact the dispatcher and give the track release:

Train 2 South, clear of the North Siding Switch Northton.

The dispatcher will mark Train 2 clear of the track between North Siding Switch Northton, and be able to issue a clearance to Train 3.

Clearance number 5 to Conductor Johnson on Train 3 North. Train 3 North may proceed from North Siding Switch Northton to Station Name Sign Zipperville.

Because Train 3 doesn’t need to normal the North Siding Switch at Northton (to save time and risk of the conductor waiting for the train to pass, normal the switch, and then walk 2000 feet to the front of the train), the dispatcher will know that any clearance through the area will have to include ‘North Siding Switch Northton may be in reverse position’. If it’s a very short train, or if the conductor can snag a ride to the head end from someone, like an maintenance foreman’s pickup truck, the conductor will normal the switch and issue a Switch Normal Report with the dispatcher. The maintenance foreman might even normal the switch after the train has passed, and issue the report himself.

This lack of control of switches is another disadvantage to OCS. Someone might not always be around to normal a switch on the line, so it’s up to the train to stop and throw a switch in order to enter a siding or pass by a siding switch without flying off the tracks. In methods of control like CTC (which we will discuss later), the dispatcher himself control the switches from the dispatch office, negating the need to be stopping and throwing switches.

Issuing clearances is typically done over the radio. The dispatcher will read the clearance to the conductor, who often has a pad of clearance forms in which the conductor fills in the blanks (a lot faster than scribbling out every word the dispatcher says). After issuing the clearance, the conductor will read the clearance back to the dispatcher to ensure the correct information was relayed. After the dispatcher confirms that the information is correct, he will ‘complete’ the form by giving the time the clearance was issued, and his initials as his ’signature’. This is called issuing a ‘written instruction’. Most, if not all ’safety critical’ clearances, reports and messages are ‘written’. Switch Normal Reports and Track Releases are not only written, they are also confirmed by a second person if available. If the conductor gives a switch normal report or a track release, they are confirmed by the locomotive engineer. Each railway has a specific methodology for making this happen.

OCS is still widely used on less important lines, and branch lines. Canadian Pacific uses OCS on some pretty busy lines still, including parts of the Transcontinental Mainline, specifically between Sudbury, Ontario and Bolton, Ontario (just north of Toronto).While CTC is easier on crews and more efficient, it is very expensive, and costs on average about a million dollars a kilometer to convert an existing line to CTC. Because of this, OCS is still in wide use, even on busy lines.

That’s the Occupancy Control System in a nutshell. Next, we’ll be discussing Centralized Traffic Control.  Thanks for reading!!

We have some plans in the works for Railsexy.com and we hope to draw some more attention and more contributors to the site.

We will be building a comprehensive user moderated rail photo archive site, to rival railpictures.net.  I am tired of hearing people who I know to be good photographers, complain about their perfectly good photos being denied from railpictures.net for stupid reasons.

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Hi all – Welcome to my first contribution on Railsexy! A little about myself, I’m a former railroader, having worked as a Rail Traffic Controller for a major Canadian railway. I got laid off, and well.. I decided not to return and instead pursue a career in a different field. I hope that my insight will help the visitors of this site to get a better idea of what goes on :)

A railway, at its most basic level, consists trains traveling from point A to point B. It seems basic enough, and when you’re only running one train on a line, you aren’t going to have any issues regarding the control of traffic. However, since time on rails is money, it makes most financial sense for a railway to operate many trains on a piece of rail between point A and point B. Almost immediately after someone invented the idea of running more than one train at once, it was discovered that trains on the same line might crash into each other if a method of control wasn’t developed - in short, someone needed t  make sure the trains don’t touch each other.

I could go into the many methods of control invented over the years to keep the trains safely apart, but I’ll save that for another entry. The most primitive and effective method to keep the trains from touching is only allowing one train into a certain area at once. This works well in very rarely used areas, and a form of this type of control is still in use today (We’ll get into that when we talk about OCS). It isn’t the most effective way of operating a railroad, though – which is why a way to safely control many trains at once is required.

Let’s say you’ve got two towns: Alphaville and Zipperville. These are two bustling towns with industry and people about 400 km apart. The two towns decide to make trade easier by constructing a railway between them. Initially there is only one train operating on the entire line, so there’s no risk of any collision accidents.

The train starts in Alphaville in the morning, and arrives at Zipperville about seven hours later, and returns back to Alphaville the next day. The railway is well used, the people are happy and industry is flourishing. The line is so well used, however, that towns spring up along the line to mine local ores and access the forestry resources in the area to be shipped to Alphaville and Zipperville. The line becomes so busy that the towns add a second train to the line. One train will carry only freight, while the other train will carry passengers. Terminals and switching yards are built at Alphaville and Zipperville, as both towns grow to become important economic and industrial centers.

Because the trains will be operating at different times, different speeds, in different directions and will be making stops along the way, a method of control is required to make sure the trains not only are able to operate safely, but profitably as well. Because it was prohibitively expensive to lay a second track along the entire 400 km route,  trains must be able to share the tracks with each other, even if they are heading directly towards each other! Passing tracks, called sidings, are therefore required. In this line, three sidings are constructed: one at Southton, one at Middlesburg, and one at Northton. The sidings are constructed long enough so that most trains operated on the line can fit inside of them. The reason for this will be made clear, and future editions of this series will show what happens when a train is too long for a siding (it happens quite a bit in the real world, which is why the RTC makes the big bucks!!)

A siding is little more than a ‘passing tracks’ that allow either overtaking or head-on trains to pass. In the old days, pretty much every town had a station and a siding. Today, many of these towns exist only in the names of existing sidings, station name signs and locations on Employee Timetables. Siding-based single track railroading is the bread-and-butter of modern railroading — most railfans who live in cities such as Toronto, Calgary or Montreal have never witnessed a ‘meet’ in real life – they do exist, and account for probably 90% of all railroading in North America. Methods of control dictate when and how trains meet, who gets put in the siding, and how this information is relayed to the crew. In Canada, there are two main methods of control: the Occupancy Control Sytem and Centralized Traffic Control.

Rail yards are often the hubs of rail activity.  But what is their function?  This article will explore the various types of yards, and their functions.

The Flat Yard

Perhaps the simplest type of rail yard is the common flat yard.   The flat yard is just that,  a flat yard, with tracks which run parallel to each other, connected by a common ladder track (or 2 common ladder tacks, one at each end).  Flat yards can be as small as a simple 1 or 2 track siding used for storing freight cars, to a massive 50 track yard used for classification and sorting.  The key to a flat yard is that all the switching is done manually.  Thus it is a slow and inefficient method for sorting and classifying cars.  In most cases these yards are usually used in industrial areas, or for regional/local yards.

Flat yards are often very simple, and use track numbering which is also very simple, often starting ‘track 1′ from the closest parallel track from the main line, and working out from there.   There are often no pre-determined receiving or departure tracks, however often these tracks will be used for the same purpose on a regular basis.  It is also rare for a flat yard to have more then 2 ladder tracks.  Busy yards may have 3 or 4 ladder tracks, however most only have 2 – one on each side.   Flat yards also rarely have more then one or two main lobes (groupings).

Hump Yard

A Hump Yard is a modern sorting facility.  Think of a Hump Yard as a grand terminal of freight.  This is where most modern freight gets sorted and classified.  Every major city has at least one Hump Yard near it, as a general rule of thumb.

The Hump Yard is actually a combination of flat yards and hump yards alike to create a flowing system.  Often there will be a group of receiving tracks which will consist of a flat yard where trains can pull into.

The locomotives of these trains will detach from their consist, and often will head to a locomotive facility for refueling and reassignment.  The locomotive shop is also another aspect of most hump yards, and is also a small flat yard used for servicing.

A local yard switcher will connect to the consist of cars that the incoming train left on the receiving tracks, and then will direct it to a ‘hump’ which is where the train will be sorted into new trains.  The switcher pushes the string of cars over the hump, which is often a small hill.  Gravity propels the cars down the hill and into an electrically controlled yard.  The car, now free of its former train, rolls into the correct track in the classification bowl to be included in a train to its new destination.  This is actually the hump of the hump yard.

From there, a yard switcher will often take a string (or rake) of cars out of the classification bowl (hump yard) and place them into a departure yard.  The departure yard is another long flat yard, which is where outgoing trains are assembled from strings of cars made in the classification yard.

In some cases, yards will have more then one hump yard, to serve either local and long haul service, or to serve eastbound and westbound traffic.  If this is the case, these yards will often have separate receiving and departure yards for each.

It is also common to have a yard within a hump yard for local traffic, as well as a yard for car storage.

Intermodal Yard

The Intermodal Yard is becoming one of the busiest types of yards on any rail system.  Intermodal yards are large spread out flat yards, with large cranes and hoists to facilitate the loading and unloading of container (COFC – Container on Flat Car) and road trailer (TOFC – Trailer on Flat Car) loads from specially constructed flat cars.

The key to Intermodal operations is that you can completely avoid humping and classifying for the most part.  Trains just run from one Intermodal yard to another, usually as high priority trains, and local loads are removed and sent by truck to their destination.  The rest of the train remains in place and is sent off to another destination.  This streamlines operation.  And while this type of operation kills the classic style of freight railroading we all grew up to enjoy watching, this is one of the biggest money makers in the freight world, and thus it keeps the trains rolling.

The Auto Yard

An Auto Yard is often a flat yard with a single ladder track on one side.   Ramps set at the dead end of each track facilitate the loading and unloading of automobiles into autorack cars.  These yards are usually surrounded by a vast sea of new cars in a large parking lot.

That basically covers all of the train yards in use today.

In the early days of Steam, and even in the first 30 years of Diesel-Electric locomotives, the challenge for any manufacture of locomotives was to get as much horsepower out of a single unit as possible.  The Horsepower Race for Steam Locomotives fizzled out when Diesel-Electrics started proving their worth during World War II.

One of the biggest selling point for 2nd and 3rd generation diesel-electrics was unit reduction.  Each unit could produce more horsepower then a previous generation of diesel-electrics, and thusly you needed fewer units to move a train.  This worked out well.  As an example:

• In 1962, 6 F unit locomotives could be used together to provide power up to 9,000 horsepower.
• In 1963, The same railroad company bought some GP30’s and used only four GP30’s to produce 9,000 horsepower.
• In 1966, The same railroad company bought some SD40’s and used three per train to produce 9,000 horsepower.

Union Pacific was always ahead of the class in terms of horsepower.  In the 1940’s it produced the 4-8-8-4 Big Boy Steam Locomotive, which was the worlds largest steam locomotive.  Not to be unmatched, it led the race with Diesels as well – often using some unique methods.  One of those methods was to use a Steam-Turbine-Electric system to power a diesel-esque looking locomotive with 2,500 horsepower, which was remarkable in 1939 when they made this happen.  In 1948 the UP used jet engine technology to create a 4,500 horsepower Gas-Turbine-Electric.

In 1958 UP teamed up with GE and created 10 ‘Big Blow’ locomotives, capable of 10,000 horsepower.  These were also Gas-Turbine-Electrics.  The UP was wild about horsepower, and in the 60’s it got Alco, GE and EMD all racing to build the UP the most powerful articulated locomotive possible.   Everyone was reaching for 15,000 horsepower.  EMD in theory won that race, with the DDA40X.  While They didn’t meet the goal, they did pretty darned good for a Diesel-Electric, pumping out 6,600 horsepower per twin engine unit.  Still the most powerful Diesel-Electric single unit locomotive ever produced.

AC Traction was the next biggest thing to come to the Diesel-Electric world.   Of course, AC Traction motors have been around for a long time,  and were known to be very efficient.  The problem was they liked to settle at whatever frequency the AC power was being provided at.  This ment that they were harder to control.  This is where computers came into play, and in the 1980’s this technology was readily available and caused a slew of AC Diesel Electrics to show up on the railroads.

AC Versions of Locomotives were often a few hundred horsepower more then their DC Counterparts.  For example, the SD70M is rated at 4,000 horsepower, while the SD70MAC is rated at about 4,300 horsepower.  EMD built a new engine to be used on AC units called the 265H which was a four cycle engine which could produce in-itself 6,000 horsepower.  This engine was an option in the new SD90MAC.  However only about 40 SD90MAC’s were produced with this new powerplant.

The reason being was that in the late 1990’s many railroads had came to realize that these 6,000 horsepower units were a waste.  Most heavy unit trains these days require a total of 12,000 or so horsepower.  If you are using two 6,000 horsepower locomotives, and one breaks down, you will not have enough power to move that train with just one locomotive.  However with 3 locomotives rated at 4,000 horsepower, chances are you will still have just enough juice to continue to your destination.

AC Traction motors and 4 cycle engines are still being used, however these days not in an effort to win any horsepower races, but more so to reduce fuel consumption.  The GEVO-12 by GE is capable of producing 4,400 horsepower from 12 cylinders.  This is a big improvement to the previous standard engine that GE used to use, which was a 16 cylinder engine, which produced about the same amount of power.

Today the ideal horsepower rating for a single locomotive has been set at around 4,300 horsepower.  And the new race is to reduce fuel consumption and to create ‘greener’ locomotives.

It is undeniable that the creation of the GP (General Purpose) 7 changed railroading drastically.  The GP7 units were designed by Dick Dilworth of EMD.  His goal was to make a road switcher which would work well “out where the real work was being done.”  The design was based on observations from Alco and Baldwin Locomotives, as well as considerations of the needs of a freight train crew.

Originally the GP7 was made with limited visibility.  This was partly because the union atmosphere at the time, wanted to keep the fireman on the locomotive, to simply watch the left side.  In reality, Firemen were kept on the crew until the mid 80’s or early 90’s in some cases – strictly due to union pressure.

Another consideration in building the GP7 with long high hoods, and a centrally located drivers cab was the consideration of the old Steam Era Engineers and Firemen.  They often liked the idea of a buffer between them and the front of the train – in case of collision.  Although these hoods were not structural, and would not stop a collision as well as a heavy boiler would, the impression of the high hood did play a key role in how popular the GP7 became.

The other critical aspect which made the GP’s popular was the control stand.  Dilworth brought in locomotive engineers from various railroads, and sat them down as a mock up engine cab.  The Engineers told Dilworth what they wanted.  And Dilworth followed through, to create a control stand, which stands in the middle of the cab, close to the right hand window.  From which the Engineer could easily operate the controls while looking either forward or backwards.  This design became the AAR Standard Control Stand.

EMD Could not produce GP7’s fast enough to keep up with demand, and opened up an Engine Plant in Cleveland, Ohio to try to meet demands.  In total, 2,729 GP7’s were produced.

The GP9 replaced the GP7 in 1954 and ended up becoming even more popular with 3,444 units being sold.  The GP18 made its debut in 1959 and augmented the GP9 until 1963 when both the GP9 and GP18 ceased production.   The GP18 was less popular, with only 350 units being built.

All in all, these GPs or Geeps were the turning point of freight operations in North America.

ITC #1605 GP7 – Photo by Sean Lamb

The Geeps were all very similar looking.  The unique differences are subtle, but easily identifiable.   GP7’s generally have 3 vents below the drivers cab, such as the photo above.   GP7’s also have a pair of grills in the access doors towards the rear of the long hood on each side.  The GP7 also had a skirt covering part of the gas tank, however in late model GP7’s and early model GP9’s the skirt was retained, however with access holes added.  Eventually the skirt was often removed completely later for access.

GTW #4621 GP9 with a short hood

DGVR #40 GP9 with dynamic breaking (as evident by the rounded vent at the top)

The GP9 is identifiable by often just one vent, or small half sized vents below the drivers cab.  The GP9 also only has one set of grills on the access hatch doors at the rear of the long hood.  And 3 sets of double grills on the central access hatch doors of the long hood as well.

An EMD GP18. Photo by Doug Kroll

The GP18 looks very similar to the GP9.  The only exception is the Fuel Fill cap, which is positioned a little higher on the GP18.  Instead of coming out of the Skirt on the GP9, it comes out of the side of the frame / lower walkway portion on the GP18.   The GP18 also had a Roots Pump Supercharger.

The authors favorite Diesel-Electric Locomotive, has to be the GP9 short-hood.  It was the most common locomotive I saw growing up near the CN Lines in and around Toronto, and the fact that the GP9’s are still kicking and in revenue service on several railroads, just proves their worth in my eyes.  These locomotives are beasts which deserve some respect.

Welcome to Railsexy.com

For those of you who have visited us before, you may notice a change.  For those of you who are first time visitors.  Welcome!

Railsexy.com is a new website set up for the discussion of trains and train spotting related topics.  We do plan on having a large photo gallery which anyone can contribute their photographs of trains to.

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