All posts by Matt Csenge

North American Railway Signaling, Part 1: Basics

July 24, 2020 Matt Csenge Leave a comment

Railway signals play a critical role in the movement of trains on a line. Generally signals convey information about the occupancy of the track ahead and whether the train can safely proceed or needs to stop. Unlike with cars, the stopping distance for a train is generally greater than the sight distance of the engineer, so the safe operation of a train is absolutely dependent on the signal system telling the engineer what to expect ahead. For this article we will stick to signals common to North American railroads, and mainly focus on signals that can be found on modern Class I railroads.

Definitions

Before we can get into the basics of signaling there are some terms that need to be defined so that the concepts will be easier to explain:

Aspect: What the signal shows (e.g. green, yellow, red, green over red, etc.).
Block: A stretch of track into which the entry of a train is controlled by a signal or other form of authority.
Diverging route: The route through the curved side of a switch (known in the industry as a turnout).
Indication: What the aspect means.
Interlocking: A group of one or more switches and associated signals.
Maximum Allowable Speed (MAS): The maximum speed at which a train is allowed to operate though an area, as defined in the employee timetable.
Name: What the aspect is called (clear, approach, stop, etc.).

Highball!

Nearly everyone in the railroading world knows the term “highball”; it’s synonymous with “full speed ahead”, and basically gives the engineer authority to start moving or continue moving. Conductors and dispatchers often use it when communicating with the engineer of a train. But where does it come from?

Quite literally, a high ball.

One of the earliest forms of railway signal used to control the movement of trains was the ball signal, which consisted of a red ball on a rope and pulley, mounted on a pole. When the ball was raised (high), it meant the next block was clear and the approaching train could proceed at MAS. So let’s continue at MAS into railway signaling!

Signaling Basics

The view from Ogilvie Transportation Center in Chicago, IL, with a sea of signals visible. Complex areas like this may use speed signaling rather than route signaling, or even “go/no go” signals.
Matt Csenge photo.

In North America, there are two general categories of signaling used by Class I Railroads: speed signaling and route signaling. The types basically do exactly what it says on the cover: speed signaling tells the engineer how fast to go, and route signaling tells the enginer what route the train is lined for. Route signaling is the more common type of signaling, with speed signaling being used in dense corridors where there are multiple routes a train could take. In these complex areas using speed signaling the engineer may not know exactly where their train will be going, but they know what speed they need to be going to get there safely. With route signaling, the engineer knows exactly where their train will be going, and has to remember (or look up in the timetable) what is the maximum speed they can be going to get there safely.

Signals are placed at two distinct locations on the railroad: block signals are placed at the beginning of a block (in any direction that a train is allowed to travel within the block) and home signals are placed at interlockings. The block signal preceeding a home signal is known as a distant signal.

The rear of a BNSF Railway coal train passing a basic block signal on Crawford Hill in Nebraska.
Matt Csenge photo.

Basic block signals consist of a single head with three lights: red, yellow, and green. On most North American railroads, each signal head can only have one light lit at a time and thus can display three aspects: stop, approach, and clear, respectively. There is also a fourth color that is used occasionally: lunar white (aka lunar), which displays an aspect known as restricting. Here is a quick explanation of what these four aspects mean:

Clear (green): The block is clear, and the next signal does not indicate stop; proceed at MAS.
Approach (yellow): The block is clear and the next signal indicates stop; prepare to stop at the next signal.
Stop (red): The block is occupied, do not proceed.
Restricting (lunar): The block is occupied, proceed at restricted speed. Restricted speed is defined as a speed at which you can stop within half of your sight distance, maximum 15 mph, expecting to encounter a train. (Why half sight distance? There may be another train coming the other way at restricting speed!)

Six-track signal gantry with distant signals on the Long Island Rail Road in Woodside, Queens, NY.
Matt Csenge photo.

Home and distant signals need more than one signal head to display a sufficient amount of information, and thus may have as many as three heads. The aspects displayed by these three heads is about the status of interlockings, so for now we will just stick with the basic four above. The aspects and indications are listed again below with the aspects for two and three head signals:

Clear (green / green over red / green over red over red): The block is clear, and the next signal does not indicate stop; proceed at MAS.
Approach (yellow / yellow over red / yellow over red over red): The block is clear and the next signal indicates stop; prepare to stop at the next signal.
Stop (red / red over red / red over red over red): The block is occupied, do not proceed.
Restricting (lunar / lunar over red / lunar over red over red / red over lunar / red over lunar over red / red over red over lunar): The block is occupied, proceed at restricted speed.

Types of Signals

Common types of signals in use on North American railroads include color lights, searchlights, position lights (PLs), color position lights (CPLs), and position color lights (PCLs). Color lights are by far the most common, and the aspects in the basics section above are those of a color light signal.

Color Lights

Color light signals are by far the most common type of signal in the United States at present. Many railroads have begun to replace other types of signals with color lights in an effort to standardize the signals across their entire system. Most color light signal heads consist of three lenses, with green at top, yellow at middle, and red at bottom. Sometimes the signal heads are oriented sideways, though this is not common. Another type is the “Tri-Light”, which features the three colors arranged in a triangular shape on a circular background. A proper tri-light would be very difficult to recreate at scale with Lego, given the triangular arrangement on a circular background.

Many designs of color light signal have been built in Lego, and have even been included in Lego sets, such as 4541. One major gripe that I personally have with these is that they are “go/no go” signals that lack a yellow approach indication. While these types of signals are often used in yards, terminals, or other slow-speed locations, they would practicaly never be used on the mainline (at least not in North America). A train would not be able to stop for a red signal if it was operating at full speed when the engineer saw the signal, which is why the approach indication is so important: it tells the engineer the next signal is red, so be prepared to stop then. This gives them plenty of time to slow the train, before they even see the red signal.

Searchlights

Searchlight signals consist of one light with an internal mechanism that moves different colored lenses in front of the light. Working searchlights are also difficult in Lego, as they would depend on a multi-color LED.

Position Lights (PLs)

A trio of Position Light signals on the Long Island Rail Road (LIRR) in Queens, NY.
Matt Csenge photo.

Position lights were developed by the Pennsylvania Railroad, and consist circular heads with lines of lights at different angles (the center light is common to all aspects). These position of these lights mimic the position of the blade of a semaphore signal, the predecessor to these signals. Most PLs have a second head with at least one light, so they can shown additional speed aspects.

Here’s an example of a Lego position light signal:

Modular PRR Position Light signal by Matt Csenge.

Position lights were installed throughout the Pennsy’s territory, and can still be found along the Northeast Corridor and the lines of many other railroads, like CSX, Norfolk Southern (NS), and the Long Island Rail Road (LIRR, sic). Variations include dwarf and pedestal PLs, which are used in yards, terminals, and other areas where a full PL is not needed. (Note that “dwarf signal” is the correct industry term for these small signals used in yards, terminals, and other restricted clearance areas.)

An Amtrak train racing past a PCL signal at Secaucus Junction station in New Jersey.
Matt Csenge photo.

Amtrak’s Northeast Corridor between New York City and Washington DC was once the Pennsylvania Railroad mainline, and thus was chock full of PLs. At some point Amtrak added colored lenses to their PLs, making them Position Color Lights (not to be confused with Color Position Lights, which we’ll talk about next). PCLs also resemble “Red Eyes” PLs, which are standard PLs with two red lights for the stop indication, but red eyes PLs have a center lamp for use with the approach and clear indications.

Color Position Lights (CPLs)

B&O Color Position Light signals.
Photo from railroadsignals.us

Color position lights were developed by the Baltimore & Ohio Railroad around the same time as PLs. They feature one main head with up to four indications (the ones listed above), and as many as six marker lights above and below the main head to display speed information. CPLs can be differentiated from PLs because there is no middle light and the aspects are in color: vertical is green (clear), horizontal is red (stop), 45° right is yellow (approach), and 45° left is lunar (restricting).

Here’s an example of a Lego CPL Lego:

Full Color Position Light signal WIP by Matt Csenge

Similar to PLs, CPLs have dwarf varitions as well:

Modular dwarf Color Position Light signal by Matt Csenge.

Additional Complexity

This covers the basics of railway signaling in North America. Getting further into route and speed signaling, home signals, and interlockings will require their own articles, as these concepts get very complex. The indications of signals vary slightly from railroad to railroad, thus adding to the complexity. I was told once that Amtrak engineers on some routes need to be able to interpret as many as 6 different types of signals by memory, as their routes use the tracks of various freight railroads and thus their signal systems too.

Here’s one fun shot I wanted to share, of a cable car signal in San Francisco. I took this shot to tease my CEE 410 Railway Signaling professor by asking what the indication is for “red X over green over green arrow over white person?” He just laughed and suggested we order another beer!

Cable car signal in San Francisco.
Photo by Matt Csenge

Building Techniques, Layout Design, Track

Track Detailing – USA: Part 2

May 29, 2020 Matt Csenge Leave a comment

As a continuation from my Part 1 of this series, here are a few more trackside details to get your creative juices flowing!

Lubricator

As Hod Carrier discussed in the UK Track Detailing article, railroads often use grease or other friction modifiers to reduce rail noise and vibration on tight curves (R40 would definitely be lubricated!). These systems consist of a wayside tank and pump, applicators mounted to the rails to dispense lubricant, and wheel sensors to detect an approaching train and begin pumping lubricant. Wheel detectors come in various colors based on the manufacturer, but dark turquoise is a good match for the ones I’ve installed in the past.

Many lubricator installations on North American railroads are out in the middle of nowhere, like an installation I did on the outskirts of Lemoyne, Nebraska (the entire town was the outskirts, honestly…) for example, where hardwired power would be very expensive to install. In these situations, it’s very common to install solar powered units. The dark blue 1×4 tiles on this design are stand-ins for 1×4 tiles with solar panel print (part no. 2431pb499).

Whistle Posts

Whistle posts are another self-explanatory item: when they see the post, the engineer blows the whistle (or horn, but horn post sounds…wrong). These are palced in advance of grade crossings so the engineer can start the telltale horn pattern of a grade crossing: long-long-short-long.

Different railroads have different designs of whistle posts. Most modern ones are signs mounted on poles, but older styles include concrete pillars with a “W” molded into them. In both of these examples, the 1×1 tile is a stand-in for the 1×1 letter “W” tile (part no. 3070bpb031). Usually the concrete post or signs would be white with black letters for better visibility, but the 1×1 letter tiles don’t come in white.

Mileposts

Mileposts are very common on railroads, since there’s an average of 1 per mile. Yes, you read that correct; track and right-of-way realignment often leads to short or long miles rather than redoing the mileposts over the entire line. These markers help train and maintenance crews know precisely where they are on the line (give or take about a mile).

As with whistle posts, each railroad has its own standard design for mileposts. In this design, the 1×1 tiles are stand-ins for the 1×1 number tiles. Placing these every mile (on average 4224 studs, for those of you counting) would be a quick way to add detail to a layout. As with the whistle posts, the signs would typically be white with black letters but the 1×1 number tiles don’t come in white.

Pole Lines

Railroads have a long history in North America, which means they have seen many different technologies come and go. Pole lines played a crucial role in delivering information from one point to another. These lines carried not only telegraph transmissions, but also information for the signal system. I could go into great detail, but I’ll save that for another article and summarize: rail lines are divided into blocks, and each block has an electrical circuit that is on when the block is empty and turns off when a train enters the block. Each wire on a pole line carries that status information along the line to different parts of the signal system.

The wires are connected to the poles with glass insulators (the trans-clear, blue, or green plates), and the pole line would also have wires connecting to every signal and relay cabinet. Here I’m using Lego string elements, but it would almost certainly be more cost effective to use non-Lego thread or string. While pole lines are not commonly used anymore, in many places they were never removed. Abandoned pole lines with broken wires hanging to the ground would therefore also be a great detail on a modern layout.

Tell Tale

Tell tales are another piece of old railroad technology that has succumbed to innovation. In the early days, before trainline braking systems, brakemen would walk the roofs of railcars applying each car’s brakes anytime the train needed to slow down. As you can imagine, life expectancy for a brakeman was relatively low. Tell tales were one of the brakeman’s safety devices: a beam extending over the track above head height with ropes dangling down. If a brakeman was walking the roof of a car and felt the tell tale hit them, they would drop to their stomach immediately! Why? Because tell tales meant that the train was approaching a tunnel or overpass, and warned the brakemen to duck or they would be hit and killed.

This tell tale is a cantilevered type, and is clearly missing the all-important ropes. This design would feature additional non-Lego ropes to support the cantilevered beam, as well as ropes to allow the tell tale ropes to be lowered for maintenance. Like pole lines, though tell tales fell out of use they were often not removed and thus would be great details on a modern layout.

Switch Stand

Switch machines, as shown in Part 1 of this series are a modern item used primarily for main lines and high-traffic switches. For low-traffic switches and branch lines, switch stands are still the best tool for the job. Switch stands are how track workers manually line the switch, by lifting the lever and rotating it 90 degrees. The red and green parts are called “targets,” and they rotate with the stand to communicate the status of the switch to an approaching train: red means the switch is set for the diverging route, and green for the straight route.

Similar to the switch machine, this switch stand design will require a bit of additional ballast extending off the PennLUG standard cross section. There are many designs of switch stands with variations of the target location and design, and the throw (lever) design and location.

Tie Colors and Types

Some railroads paint their crossties different colors for different purposes. Union Pacific (UP) paints a tie blue at every culvert crossing under the track (blue=water, right?). They do this because often the culverts are pretty far down in the subgrade under the ballast, and often the inlet and outlet become obscured by brush. The blue tie helps maintenance crews locate culverts so they can check if they need to be cleared out, thus preventing washouts. Similarly, Amtrak often paints ties yellow when there are gauges or instrumentation mounted on the tie and they want tamping crews to be careful while maintaining the ballast around those ties. The defect detectors shown in the image are from Part 1 of this series. The culvert design is more suited to a MILS module than the PennLUG standard ballast, but the blue tie can be placed independently.

Varying the type of ties on your layout can also be a simple way to add some detail. While branch lines and short line railroads may use exclusively wood ties, most Class I freight railroads (BNSF, CSX, CN, etc.) do not use just one type of tie from end to end. There is a wide variety of materials that crossties are made from, as well as the forms those materials come in. Concrete ties are used for high tonnage or high speed lines; plastic composite ties, synthetic ties, and tropical hardwood ties are used in wet areas where treated hardwood would be susceptible to rotting; and steel ties are sometimes used in yards, as they need less ballast than regular wood ties.

From left to right in the image above:

Reddish brown tiles representing wood ties (my personal color of choice for wood ties),
Dark tan tiles, representing a tropical hardwood tie,
Medium nougat tiles, representing a Fiber-reinforced Foamed Urethane (FFU) synthetic tie,
Two versions of concrete dual-block ties, one with studs for the fasteners, represented by light bluish grey tiles and plates,
Three versions of concrete ties using different tiles and plates, represented by light bluish grey tiles and plates to for different designs,
Two versions of plastic composite ties, represented by black or dark grey ties (on dark bluish grey ballast),
Dark brown tiles and plates, representing a steel tie.

Concrete ties come from multiple different manufacturers, each with their own designs. If a railroad had multiple types installed they would typically be in large sections, rather than a mix of different ties. Concrete ties and steel ties typically use elastic fasteners rather than steel plates and cut spikes used on the other types, so the chunkier fasteners can easily be represented with the stud of a plate. Dual-block concrete ties have a steel beam in the middle connecting them, which would be buried in the ballast. Though they have yet to be widely accepted by North American railroads, some railroads are experimenting with dual-block concrete ties. Steel ties are not commonly used on signalized tracks as the rails need to be electrically isolated for the signal system to function properly. Additional variation can be achieved by mixing slightly different colors, like reddish brown and brown for wood ties, black for weathered wood ties and brown or reddish brown for new wood ties, and light bluish grey and light grey for concrete ties.

Some railroads also have test sections of track where multiple different types of ties are installed, with measurement devices monitoring their performance and wear. Shown above is a possible test site, with small bunches of multiple different tie types, relay cabinets housing testing equipment, and a pile of old crossties that were removed from the track, including a broken concrete tie. (See Part 1 of this series for more of the relay cabinet and piled ties) Piles of new ties of any kind would also be fitting!

Hopefully these examples help get some ideas going. Be sure to share photos of the details of your layout to inspire others too!

Building Techniques, Layout Design, Track

Track Detailing – USA: Part 1

May 21, 2020 Matt Csenge Leave a comment

After Hod Carrier’s wonderful article on UK track detailing, we thought it’d be good to look at track detailing for North America as well. These digital designs represent details found on American railroads and though the designs were based specifically on my experience with railroads in the United States, railroads in Canada and Mexico tend to follow similar practices and use similar equipment. All of these designs are compatible with the PennLUG standard of track building, instructions for which are available for free at l-gauge.org.

Dragging Equipment Detector (DED) and Hot Box Detector

Defect detector is a general term for a number of wayside vehicle monitoring devices used by railroads to inspect the cars in their train as they pass. Some common types of defect detectors include Wheel Impact Load Detectors (WILDs), Dragging Equipment Detectors (DEDs), Hot Box Detectors (HBDs), and Automatic Cracked Wheel Detectors (ACWDs). These detectors monitor the train as it passes over them and log and alert the crew to any defects that are detected, so that the offending car can be scheduled for repair or removed from the train.

Here I’m focusing on DEDs and HBDs. DEDs (at left) consist of sensors mounted between ties that deflect, or bend when a dragging piece of equipment, like a chain, strikes them. HBDs (at right) use an infrared detection system to monitor the temperature of the journal bearings where the car sits on the axle. If the journal is too hot, there is a problem with the axle causing too much friction. These two detector types are some of the most common on North American railroads, and are often sited together. When sited with a DED, the HBD will have guard slopes on either side to ensure any dragging equipment doesn’t damage the sensors.

Lego’s new Slope 45 1×1 Double (part no. 35464) is perfect for the DED. The 2×2 tile represents a junction box where the wires for the detectors would come together before going to a relay cabinet (shown later).

Derailer

Derailers, also known as derails, are installed in places where the consequences of derailing a train or car are less severe than the consequences of not derailing the train or car. The most obvious example would be at a movable bridge: when the bridge is open (raised) the derailer would be set to derail a train, as derailing the train is not as bad as the train crashing into the river below.

This type of derailer is known as a hinged derailer, which sits on top of the rail and lifts the wheel over the rail. These are commonly seen in yards or on industry sidings, to prevent stored railcars from rolling out onto the main line. In the US, the Federal Railroad Administration (FRA) requires industry sidings from main lines to have derailers installed for this purpose. The FRA also requires them to be painted a clearly visible color, like yellow. As the name suggests, the derailer has hinges so that it can be folded into the gauge of the track (i.e. between the rails) so cars can pass over it.

Here’s two versions of a hinged derailer, one in the derailing position and one in the open position. The blue sign is an optional feature, which is typically used when workers are doing maintenance on a piece of equipment. The “open” derailer requires a bit of modification of the track structure in order to get the tooth plate upside-down, but allows for it to be included on the layout without preventing use of a track.

Switch Machine

Mainline switches on most railroads are controlled remotely by a dispatcher, and switch machines have the job of physically moving the switch. There are many models of switch machine produced by many different manufacturers, and this is a representation of just one type.

The switch machine requires a bit of expansion of the ballast section under the tracks. The black tile at the top represents a junction box where the wires go into conduit to be run to a relay cabinet.

Switch Heaters

The purpose of a switch heater is pretty straightforward. Parts of North America are subject to low temperatures and heavy snowfall in the winter, and many switches are susceptible to freezing or getting packed with snow and becoming inoperable. Switch heaters use a wayside generator and ducts between the switch points to blow hot air into the movable part of the switch to prevent freezing of snow buildup.

This design uses the new Bracket 1×1 – 1×1 (part no. 36841) to connect the hose to the ballast section, making it look like the hose is buried in ballast.

Relay Cabinet

Relay cabinet is a general term for wayside electronics cabinets on the railroad. The name comes from the signal relays, or magnetic switches, that they originally housed. Shown here are two types, a smaller, older style at right, and a larger, newer style at left. These cabinets are not used exclusively for relays, and they can be found at signals, switches, defect detectors, grade crossings, and numerous other locations along the railroad.

Using Lego’s door parts allows for the interior of the cabinets to be detailed as well. This one includes a junction box at left, battery backup in white at bottom, and three magnetic relays using trans-clear headlight bricks (part no. 4070) and round plates to represent the magnetic coils. The large cabinet features headlight bricks at the roof representing the lifting points, as these are installed by crane. These features could make for fun vignettes, with signal maintainers working inside the cabinets or using a crane to install a new one!

Piled Ties

Maintenance on North American railroads is often carried out by track gangs; large teams of workers specializing in replacing one component of the track. Typically the materials for these gangs are dropped along the track in advance of them arriving at the worksite. Thus, it’s common to see bundles of new ties and buckets of spikes, clips, or other track materials along the right of way.

Similarly, old ties are often piled or discarded along the right-of-way awaiting a crew to pick them up (or simply being left to decompose). It’s pretty common for these ties to be deteriorated or have plates still attached to them, so in this case studs showing is a good thing!

Hopefully these ideas help get the creative juices flowing and give you some ideas to add detail to your home or club layout!