Reading Society of Model Engineers
Reading Society of Model Engineers

Berks County, Pennsylvania, USA


RSME Member Written Articles
Written By: Russ Ingham
Written By: Craig Ingham
Signal Application in Model Railroading
Written By: Craig Ingham

Above is a list of articles that have been written by RSME Members for publication in both our RSME newsletter "Timetable" and the RSME website. As new segments are written they will be added into the appropriate set of articles. Please click on a link above to read threw the articles.


Part 1

August 1996

Part 2

October 1996

Part 3

February 1997

Part 4

April 1997

Part 5

December 1997

Part 6

February 1998

Part 7

June 1998

Part 8

August 1998

Part 9

October 1998

Part 10

December 1998
Part 11 August 1999
Part 12 February 2002
Part 13 April 2002
Part 14 June 2002
Part 15 October 2002

Signals (Part 1)
by Craig Ingham
(August 1996)

You might have noticed that I typically sign off with "high greens to all". Most of us know that means a clear track ahead. Our understanding of the signals along the trackside is generally limited to a comparison of traffic signals we encounter on the streets we travel. On the roadways, the most complex signal we encounter is one with an extra lens with an arrow. Next time you see a signal on the railroad, take note of the various shapes and arrangements. You may note that signal shapes and arrangements change between divisions and railroads. Imagine being the engineer who must operate a train through the maze of differences. Almost without exception, regardless if the signal has one or more heads, the physically highest head governs your action. A green over any other color will indicate a clear track ahead. Any color below the high green is supplementary information and does not alter the fact that you are cleared to proceed at the accepted speed limit. These limits are regulated as posted or by "train orders". If you were to see a green over red over red, you would know that you have a clear track ahead. May all your tracks be clear.

to be continued...

Signals (Part 2)
by Craig Ingham
(October 1996)

As was suggested in the first installment, signals provide the train crew, specifically the engineer, with visual indications (instructions) as to clearance, speed and routing. It is a method for remotely providing the train crew with current right-of-way status. The first basics to understand are the terms aspect and indication. Aspect refers to the physical appearance of the signal. Indication refers to the information that the specific aspect conveys. Furthermore, each aspect has a name.

There are three basic signal aspects: stop, approach and clear. As the engineer, you are responsible to control your speed at a rate that provides a sufficient response time. This may be in response to the next signal or conditions between the immediate signal and the next signal.

Learning the names of the indications will help in understanding the indications. If the signal name ends with the word approach, or this is the only word, the engineer must be prepared to stop at the next signal. When speed is the first word of the name, you are in an interlocking machine and may proceed at that speed. These speeds are generally defined in the "rules" book. Also, when speed is the last word in the signal name, the engineer must change his speed before passing the next signal.

There are exceptions to every set of rules. A medium approach, which is found only at interlocking, is the only speed fixed signal requiring action before you pass it.

The three speed terms are slow, medium and limited. Their rates are in ascending order.

Now for the test #1! Assuming the rule book has established slow=15mph, medium=30mph and limited=40mph; define the signal indication for the immediate and next signals for the names slow approach, medium approach, slow clear, medium clear and limited clear. Caution, so far the physical signal has not been established, only the name and indication have been discussed.

to be continued...

Signals (Part 3)
by Craig Ingham
(February, 1997)

First, the test! Slow Approach-proceed at maximum of 15 mph and be prepared to stop at next signal. Medium Approach-proceed at maximum of 30 mph and be prepared to stop at next signal. Slow Clear-proceed at maximum of 15 mph within the interlocking and normal speed beyond the interlocking. Medium Clear-proceed at maximum speed of 30 mph within the interlocking and normal speed beyond the interlocking. Limited Clear-proceed at 40 mph within the interlocking and normal speed beyond the interlocking. How many of you answered correctly? By the way, the reference for this is the NORAC rules.

Now, let’s take a look at signal names with Approach as the first word. Approach Slow, Approach Medium and Approach Limited are indications requiring the engineer to slow down before passing the next signal. This signal is typically used in situations where insufficient distance or vision limitations exist which would make responding to a signal difficult. Using the same speed rules from the test, a Slow Approach allows the engineer to proceed approaching the next signal at slow speed; any train exceeding medium speed must at once reduce his speed to medium as soon as the engine passes the immediate signal. The example would be a train at 30 mph must reduce its speed to 15 mph before it reaches the next signal. If that train is at a speed greater than 30 mph, it must immediately reduce its speed to 30 mph as the engine passes the Approach Slow signal. For the Approach Medium and Approach Limited signals, the engineer must reduce his speed to 30 mph and 40 mph respectively before reaching the next signal.

So far we have learned three basic rules. Rule #1-when the word approach is the last (or only) word in the name, always be prepared to stop at the next signal. Rule #2-when speed is the first word in the name, proceed at that speed. It is an interlocking signal. Rule #3-when speed is the last word in the name, reduce to that speed before passing the next signal.

Are you ready for Rule #4? When the word Advance is included in the name, instructions applicable at the next signal are advanced or postponed to the second signal. This signal aspect is used when the length of the block is short and allows two blocks to take the required action. Included in the rule definition is a requirement that trains exceeding limited speed must, at once, reduce to that speed as soon as the engine passes the immediate signal.

These four rules provide the basics for understanding signals and their displayed aspects. Study parts one and two carefully before we move into the color and position signal aspects.

I have been asked how long this tutorial will last. Well, I looked at a Reading Company Rules of the Operating Department that became effective January 1, 1968, and it lists one thousand six hundred twenty (1620) rules. I also am looking at The Consolidated Code Of Operating Rules-Revised 1959 that covers 13 northwestern railroads and has over 1255 rules. These engineers frequently traversed from two to four of these railroads, and their different signals, in one run. Guess it ain’t that easy to be an engineer!

Our next installment will begin to cover the actual displays of color and position signals. In the meantime, another test. Do you know the when rules 251 thru 254 are used versus rules 261 thru 264?

to be continued...

Signals (Part 4)
by Craig Ingham
(April 1997)

In the last session, it was asked when rules 251-254 and 261-264 were applicable. Rules 251,253 and 254 govern the movement of trains in the same direction by block signals. Rules 261, 262, 263 and 264 govern opposing and following movements of trains by block signals. Generally speaking, 251-154 allow movement by timetable and superiority with ultimate control by block signal and any known condition that will delay or prevent a train from making usual speed must be reported to the train dispatcher in advance. Rules 261-264 are in effect when more than one train is operating on the same track and/or your train needs to be moved in the opposite direction from the established schedule. Under this condition, the train does not move without proper signal, train order or supervision of the train dispatcher who will issue instructions to operators when required. In either case, the signals and dispatchers are superior.

Single, double or triple signals may be used to convey instructions to engineers, trainmen or track car drivers. The most involved instruction determines how many signals are used. The name of a signal is read from top to bottom. When RED is used with GREEN or YELLOW, it is of no concern. Only the positions of the GREEN and YELLOW are consequential. For example; G-R-R is clear to proceed at normal speed, R-G-R is medium clear to proceed at medium speed within interlocking limits and through turnouts while R-R-G is slow clear to proceed at low speed within interlocking limits and through turnouts. There is one additional clear indication, R-G(blinking)-R, limited clear to proceed at limited speed within interlocking limits and through turnouts. Notice the position relationship to speed limits while still conveying a clear condition.

Likewise, a YELLOW is treated in similar fashion with position conveying speed limits. It is considered an APPROACH indication and requires being prepared to stop at next signal. For example; Y-R-R is approach prepared to stop at next signal-reduce speed to medium as engine passes approach signal, R-Y-R is medium approach-reduce speed to medium as soon as signal is clearly visible and R-R-Y (blinking) is slow approach and proceed prepared to stop at next signal- slow speed within interlocking limits and turnouts and then proceed at medium speed. A steady YELLOW at the low position now becomes RESTRICTING. R-R-Y is proceed at restricted speed until entire train has passed a signal displaying a less restricting aspect. Notice that they are all approach situations.

The next installment will involve signals with combinations of GREEN and YELLOW lights.

to be continued...

Signals (Part 5)
by Craig Ingham
(December 1997)

In the last session, signals involving a GREEN or YELLOW with RED were discussed. This session will begin to mix GREEN with YELLOW displays. Before we continue, let’s review some basic rules that pertain to signals. First, the name of a signal indication is read from the top position down. Second, the top color (GREEN or YELLOW) defines a CLEAR or APPROACH indication. Third, a GREEN or YELLOW in the middle position indicates medium speed. Fourth, a flashing color in the middle indicates LIMITED SPEED. Fifth, a GREEN on the bottom indicates SLOW SPEED. Sixth, if it’s not all RED, it’s not RED at all.

Daily, while crossing the intersection at Tuckerton, I typically see one of three indications on the south bound signal controlling the traffic into the Reading yards or around the city. R-R-R preventing traffic into the junction, Y-R-R indicating APPROACH (Rule 285) to the junction and Y-G-R indicating APPROACH MEDIUM (Rule 282). Unfortunately, I have not been able to view the route taken nor the conditions ahead of the train, so I do not know what dictates these indications. This specific location is the beginning of a series of signals that govern train routing around Reading, into the Reading yards, or west bound through Reading parallel to Buttonwood Street.

From our previous discussion, we know that the APPROACH indication instructs the engineer to approach the next signal prepared to stop. The APPROACH MEDIUM indication instructs the engineer to proceed and approach the next signal at medium speed.

What is the difference? An APPROACH signal requires the engineer to immediately reduce the train speed to MEDIUM. An APPROACH MEDIUM does not require immediate response but directs the engineer to approach the next signal at MEDIUM speed. This would suggest that an APPROACH signal is more restrictive and the next block is either occupied or not clear for other reasons.

This brings us to an interesting twist. Under NORAC rules, a Y-G-R aspect, the GREEN is blinking, would indicate APPROACH LIMITED; proceed approaching next signal at LIMITED speed. However, the January 1968 Reading/Conrail rules show APPROACH LIMITED (Rule 281B) as Y-G-G. Re-qualification to NORAC rules must have been a strain for some of the "old timers." By the way, the 1959 issue of "The Consolidated code of Operating Rules" for the C. M. ST. P. & P. R. R., GREAT NORTHERN, M. ST. L. RY., SOO LINE/DSS&A/MN&S RAILROAD, N. P. RY, S. P. &S. RY. and the UNION PACIFIC did not have an APPROACH LIMITED aspect.

The next installment will take a look at APPROACH SLOW. Take a stab at the aspect for that indication.

to be continued...

Signals (Part 6)
by Craig Ingham
(February 1998)

This installment will cover the APPROACH SLOW signal and its aspect. This means to proceed approaching the next signal at slow speed and trains exceeding Medium Speed must begin reducing to Medium Speed as soon as the engine passes the APPROACH SLOW signal.

If we remember the past sessions, the first word is APPROACH and therefore requires the top position to be YELLOW. The center position is RED and contributes nothing to the name. The lowest position is GREEN; because it is on the bottom, it means slow.

On occasions, I have noted signals that only have a top and bottom display with a space in the middle. The missing signal indicates the same information that a RED aspect would infer. This would mean that this signal location never requires a speed order. It will either be CLEAR, APPROACH, STOP, APPROACH SLOW or RESTRICTING. I suspect that these will eventually be replaced as the systems are upgraded.

Just when you may have begun to think that you understand signals, we find that the NORAC rules provide for another aspect of APPROACH SLOW indication. YELLOW, YELLOW, RED is also APPROACH SLOW and is an exception to the rules we have discussed so far. In this case the middle signal does not indicate MEDIUM SPEED. The January 1, 1968 Reading Company Rules of the Operating Department, Rule 282A refers to this as an ADVANCE APPROACH signal. Under this, the engineer was to proceed prepared to stop at second signal. If one looks at this closely, the two are not very different in intent.

With the next installment, we will look at high signals with only two heads. Generally speaking, they will be the equivalent of the three headed signals.

to be continued...

Signals (Part 7)
by Craig Ingham

(June 1998)

This installment will begin to cover aspects of two headed signals. The basic rule of thumb to follow when looking at two headed signals is to assume the third, or lowest head, is always RED. Generally speaking, the signals will represent the same aspect and instruction covered by the three headed signals.

We will start with a RED over RED. The obvious is STOP. If the signal has a number board near the bottom of the mast, it is a permissive signal and instructs the engineer to stop and then to proceed prepared to stop.

A GREEN over RED is a CLEAR signal to proceed at the allowed speed limit as posted or by orders.

A RED over GREEN is MEDIUM CLEAR. The engineer is to proceed at medium speed within the interlocking limits and through turnouts. However, if the GREEN is blinking, it is a LIMITED CLEAR and the engineer must slow to a more restricted limited speed as posted or ordered.

According to 1959 issue of the Consolidated Code of Operating Rules, as used by C. M. ST. P. & P. R. R., G. N. R. R., M. ST. L. RY, SOO, U. P. R. R., N. P. RY and S. P. & S. RY, all but the last two used the RED over GREEN as DIVERGING CLEAR; proceed on diverging route. The N. P. And S. P. & S. considered it as a MEDIUM CLEAR. None of the these show the LIMITED CLEAR aspect in these operating rules.

Also of interest is that the Reading Co. January 1, 1968, rules book, rule 281C, shows LIMITED CLEAR as a RED over GREEN over GREEN.

A YELLOW over RED is APPROACH. As in the single or three head signals, the engineer must slow and approach the next signal prepared to stop.

It is important to remember that we are talking about the standard high signals up to now. Dwarf signals are not necessarily the same. We will get into them at a latter time.

Following this line of thinking, take this test and identify the following aspects:


YELLOW over blinking GREEN


Blinking YELLOW over RED

I would like to review rules books, current or past, from other railroads. This information will be used as an expansion to this series of articles. I am finding the similarity and differences in signaling as it was and is used across the USA. Your feedback will be greatly appreciated. I would also like to hear from current and past engineers describing their experiences with signals, the humor and the tragedy.

to be continued...

Signals (Part 8)
by Craig Ingham

(August 1998)

The test from the last article, 7th Installment, is answered here:

1. YELLOW over GREEN is approach medium

2. YELLOW over blinking GREEN is approach limited

3. YELLOW over YELLOW is approach slow

4. blinking YELLOW over RED is advance approach

As always, there are exceptions. RED over YELLOW is a restricting signal and the engineer must proceed at Restricted Speed until entire train has passed a signal displaying a more favorable aspect or has entered a MSB (Manual Block System) territory. This is the same meaning as the RED over RED over YELLOW.

If the YELLOW is blinking, the aspect changes to mean medium approach. This is Medium Approach which is the same as RED over YELLOW over RED. With this aspect the engineer is to proceed at Medium Speed preparing to stop at the next signal. If the train was exceeding Medium Speed, it must begin to reduce its speed as soon as this signal is clearly visible.

Generally speaking, the two headed and three headed signals are very similar. As a reminder, with two headed signals, imagine that the lowest head is always red.

The dwarf signals will be the topic the 9th Installment. Across the country and through the years, Dwarf signal styles varied as a function of the owners desire or as inherited through acquisition. The general statement that can be made is that a railroad would use dwarf signals similar to the high signals used by that railroad. They typically had only one or two heads. The heads were either position, target ("bulls eye") or semaphore. Some others were lenses placed in a triangular pattern or the familiar "traffic light style." If any one knows of another style, please advise. As indicated by the name "dwarf," these signal heads sit close to the ground. They are used in place of high signals when it is not practical to install a standard height signal. As you drive around the Reading area, you will find many of these directed at trains running against the normal flow of traffic.

to be continued...

Signals (Part 9)
by Craig Ingham
(October 1998)

How many of you got the right answers to the questions from installment 7?

Now to the dwarf signals. We will find similarities and differences when comparing them with the standard height devices.

As always, whether single or doubled headed, RED means stop. If the signal has a number placard and is within the interlocking machine, this indicates the train must stop and proceed. If the aspect is GREEN over GREEN, clear is the order. Easy so far! But what if the aspect is a single GREEN? A single GREEN and a GREEN over RED is slow clear. See how the differences come in.

Another difference is a single YELLOW. One would expect this to be an approach aspect, but no-o-o, it is a restricting signal. The single YELLOW and the RED over YELLOW both indicate restricting. So then, where is the approach aspect? There isn’t one. With only one exception, an approach aspect will be modified with a speed compliment.

In the tenth installment, we will discuss the four aspects of dwarf clear signals. Comparisons of the NORAC rules with older Reading and western roads will be made. The eleventh will focus on the approach configurations and comparisons.

to be continued...

Signals  (Part 10)
by Craig Ingham
(December 1998)

We will discuss the four aspects of dwarf clear signals per current NORAC rules and the AMTRAK instruction.

GREEN over GREEN is clear . This is the same indication as a high GREEN or a high GREEN over RED over RED. With this aspect, the engineer may proceed at the posted limits.

If we change the aspect to a GREEN over RED or a single headed GREEN, this is a slow clear and the indication is to proceed at slow speed within the interlocking limits.

Now, change the aspect to GREEN over blinking RED and the you now have a medium clear. Please note that there is no single head signal for this dwarf configuration.

The limited clear aspect is either a blinking GREEN over RED or a single head blinking GREEN.

I have been looking at the 1968 Reading rule book and found some differences. At that time, the Reading considered medium clear to be a GREEN over RED (rule 283); note that it is now slow clear under NORAC. The same book shows the single head GREEN to be a slow clear (rule 287) ; no change to the present NORAC rule. The GREEN over GREEN or clear was Reading rule 281.

Review of the 1959 Consolidated Code of Operating Rules, which governed northwestern and Union Pacific trains vary to some degree. There are no GREEN over GREEN aspects. Generally, the GREEN over RED or a single headed GREEN were clear indicating proceed or proceed on main route. This was true for C.M.ST.P.&P.R.R. rule 240-G; G.N.R.R. rule 240-G; M.ST.L.RY. rule 240-G; SOO, DSS&A and MN&S R.R. rule 240-G; U.P. rule 240-G; N.P.RY. and S.P.&S.RY. considered single GREEN with number plate as ABS rule 501-C and within interlocking, the single GREEN and GREEN over RED were slow clear, rule 601-G. Sound simple enough? I wonder what the southern and central roads used?

I have not found a good description, or rule, that governs where and when the dwarf signals are placed. Generally, I typically see them in yard areas and on opposing direction right-of-way within a interlocking machine. A convenient place to observe a working dwarf, used under current NORAC rules is at Blandon. At the Route 73 crossing, the single track to/from Reading becomes two tracks north from/to Allentown. These tracks are used as directional mains with signal provisions for opposing traffic. The normal south traffic to Reading is controlled by a high signal and the north bound track, when used by opposing traffic, is controlled by the dwarf. If I am not mistaken, this dual trackage from Blandon thru Fleetwood and north toward Allentown is considered an interlocking machine. I am not familiar with the route and its configuration north of Fleetwood. If you go there, be careful; you will be on railroad property or other private property.

Please note: I am still looking for input from an "expert" who can provide insight to when and where the various signals are placed. Any signal maintainers or engineers out there?

The next installment will focus on dwarf approach aspects.

to be continued...

Signals  (Part 11)
by Craig Ingham
(August 1999)

We will discuss the four aspects of dwarf approach signals per current NORAC rules and the AMTRAK instruction.

YELLOW over YELLOW is approach slow. This means to proceed approaching the next signal at slow speed. Train exceeding medium speed must begin reduction to medium speed as soon as engine passes approach slow signal.

YELLOW over BLINKING RED is approach limited. Proceed approaching next signal at limited speed.

YELLOW over GREEN is approach medium. Proceed approaching next signal at medium speed.

YELLOW over RED or a single BLINKING YELLOW is slow approach. Proceed prepared to stop at next signal; slow speed within interlocking limits and through turnouts; then proceed at medium speed.

YELLOW over BLINKING RED is medium approach. Proceed at medium speed preparing to stop at the next signal. Train exceeding medium speed must begin reduction to medium speed as soon as medium approach signal is clearly visible.

RED over YELLOW or a single YELLOW is restricting. Proceed at restricted speed until entire train has passed a signal displaying a more favorable aspect or has entered MBS (Manual Block System) territory.

The 1968 Reading Company rules show the Y/Y as advance approach. Proceed prepared to stop at second signal. Notice that it referenced the engineer two signals ahead. The western roads, per the 1959 edition, did not have this signal. A new resource, CSX rules as of 1 January, 1999, has a dwarf color position approach slow that is vertical GREEN with a top right offset YELLOW as well as a Y/Y, rule 283-C.

The 1968 Reading Company rules does not list a dwarf approach limited or a Y/ FG nor does the 1959 western rules. The CSX rules have the same indication as NORAC.

The Reading and CSX had/have a Y/G, Rule 282, approach medium, that coincides with the NORAC rules. The NPRy & SP&SRy lists a rule 601-K listed as flashing slow clear, approach medium that is FY/R or FY.

The NORAC slow approach, Y/R is rule 288 on the CSX and the Reading. The NPRy & SP&SRy listed it as rule 601-E. The NORAC FY is/was not used by any of these. The CSX uses a Y and the western roads, with the exception of NPRy & SP&SRy, rule 240-E lists it as approach.

The NORAC restricting, R/Y and Y, was Reading rule 290 and NPRy & SP&SRy rule 601-F. The other western roads only had R/Y, rule 240-H. The CSX, 1999 rules lists the R/Y configuration as rule 286 as medium approach. The CSX restricting dwarf signal, rule 290, is D(dark)/R, R/D or D.

It’s no wonder why engineers "sweat out" taking their routine qualification tests. One can begin to see why an operator doesn’t typically jump from one division to another without a requalification or familiarizing period.

Please note: I am still looking for input from an "expert" who can provide insight to when and where the various signals are placed. Any signal maintainers or engineers out there?

The next installment will focus on Pennsy style position aspects.

to be continued...

Signals  (Part 12)
by Craig Ingham
(February 2002)

First, I must apologize for not keeping up with the article. Secondly, you “rivet counters,” please excuse the fact that I am not covering what I said I would in the last installment. Also, I have received some feedback from “visitors” to the RSME web page. This feedback has been helpful and addresses some of the questions that I posed in the previous articles. I will try to get this data compiled and share it with you through out 2002. Recognition will be given to the sources that provided the input.

For the moment, I am going to focus briefly on the “Banjo” signal. This discourse will cater to the younger readers and/or those who are not familiar with this style of signal by describing the design and operation of this signal. As most of the RSME members know, our member, Harry Zimmerman and his wife Beverly, have been refurbishing the RSME’s “Banjo” signal as time allows. They are far enough along that we must seriously consider where and how to display this piece of history. I will try to acquire information as to the signal’s origin.

banjo.jpg (45800 bytes)

The “Banjo” signal made its first appearance in the very late 1800’s, probably around 1870, and was in use on various railroads well into the early to mid 1900’s. I have seen a number of pictures that show them in use on the Reading commuter lines as late as 1945. Our “O” gauge railroad has an operational model of the combination Banjo and semaphore signal that controlled access to Reading, PA, at what was called Klapperthal Junction, located just east of Reading near the Titus power plant. I am not sure when this signal was replaced with the conventional colored triangular Reading signal, possibly around 1950 or earlier. A now deceased member, I. Russell Shull, built this model in the late ‘60’s or early 70’s but never got to motorize it (one of the many items on the “to do” list).

The name “Banjo” was attached to this signal because it looked like an upside down banjo as mounted on its post. Like other types of signals, certain features and colors were used to define its purpose and attributes. I must do more research on the colors that were used throughout the country. However, the color scheme that I have personally seen was a white “face” with a black back. The limited information I have on these signals indicates the standard conformance of most, if not all signals, was the black or non-highlighted backside of a signal prevented errant recognition of the signal. The white “face” was bold enough to be seen in the daylight and at night when illuminated by the headlight of the engine. This type of signal was possibly the last version of the “enclosed disk signal” and was developed from the original exposed “ball” or “disk” signals. These exposed signals provided a colored ball or disk shaped device to be raised to signal the engineer. The down side of these was that they were only useable in daylight hours. As the demand for railroad operations required night operations, changes were made and lighting was added. Initially, lanterns inside the “ball” or behind the “disk” provided illumination at night or during limited visibility. As automation and maintenance factors entered the picture, changes were again made and the signals were improved to permanently enclosed “heads” with integral lanterns, still requiring someone to climb the mast and light the “coal oil” or kerosene lantern, with mechanisms to manually move internal filters over the lens. Later, as signals were electrified, the manual operation was replaced by an electrical relay, the “Hall” electro-magnetic actuator, crude by today’s standards, powered by batteries in remote locations or by power derived and transformed from the nearby tower or station.

The enclosed disk signal began to take various shapes, based on the manufacturer or the specific railroad, and the “Banjo” was born. It’s size, shape and short neck was very noticeable to the engineer; the round head is about 42” in diameter. Several pictures show two versions, probably indicative of early and later generations.

One version shows one display opening and the other shows two display openings. The primary display port is on the vertical centerline and horizontally centered in the lower half of the head. This location allowed the colored silk disk, 2’ in diameter, to swing out of sight above the opening. The illuminated versions had an external standard lamp bracket on the back of the head to mount signal lanterns over an opening to light the display.

The other version had two openings on the face of the head. This style had the same large, lower portal described in the previous description, plus a smaller opening placed high on the vertical centerline. The large lower opening provided for daylight aspect presentation while the smaller had a lantern mounted as described previously for night and limited visibility operation illuminated higher opening. This required two disks, the larger one and a smaller one (also a colored silk disk but about 6” in diameter), offset so that they were simultaneously displayed or hidden. The lever mechanism they are mounted on is counterbalanced and will drop to the most restricted aspect if the relay (electro-magnetic actuator) fails.

These signals provided the typical aspects that were previously discussed, however, there were several limitations because there were only two positions as opposed to the three-color configurations that we are more familiar with. The Banjo could be found as a standard block signal in the normal height mounting with the large lens centered vertically at nine feet above the railhead or as a dwarf, located closer to the ground. With in interlocking or where blocks required multiple signals due to limited sight restrictions, a two headed configuration was used; one head above the other and in certain situations, offset left and right of the mast to define its aspect. As with the three-color signals, the upper head is the “home” or immediate signal and the lower head is the “distant” signal. An example of a “home” signal would be red for stop and clear/white for proceed. The “distant” head would be one of two configurations; green for caution and clear/white for proceed or yellow for caution and clear/white for proceed. I am certain that there are other color combinations so there is obviously more research to be done.

I will detail the specific dimensions of our Banjo signal for the next article.

to be continued...


Signals  (Part 13)
by Craig Ingham
(April 2002)

The Banjo signal dimensions that I spoke of in the last newsletter will be covered in the next article. Quite simply put, each time I went to the RSME to measure it, I couldn’t remember what I had intended to do. I am suffering from a very common, but incurable, disease – CRS (Can’t Remember Stuff). Therefore, I will begin discussion on the semaphore style signals.

The semaphore, like the “Ball”, Banjo and other early mechanical signal devices, relied on the physically positioning of the indicating element to represent its aspect. Again, the aspect is the information relayed by sight to the engineer and crew of the approaching train.

For those of you with a nautical interest (all you “Dixie cup” wearing “swab jockeys” who may have worn a signalman strikers’ crossed flags), you already know the definition of semaphore. However, for the rest of the readers, Webster defines the term in three ways:

1. Any apparatus for signaling, as by an arrangement of lights, flags and mechanical arms on railroads.

2. A system of signaling by the use of two flags, one held in each hand. (I tried holding both of them in one hand, but it didn’t have the same effect.)

3. Any system of signaling by semaphore.

The position of the flag, or arm, relative to itself and to the other flag, or arm, indicates a piece of information. As the relative positions change, the expressed information is changed. So far, even I can understand this.

This is all great as long as there is clear visibility. Early in the use of this type of signaling, their use was only practical when one could see it. As with the Banjo signal, eventually lighting was added to them, as night operations became a fact.

The railroad’s use of the semaphore began in the mid to late 1800’s, in the United States, and there are still a few in daily operations today. Their use is quickly ending as the railroads are upgrading and replacing old devices with more modern, more efficient and better automated signals. Safety and maintenance costs are driving this move. Europe has been using semaphore devices for many years, but I don’t know when they first started. Unlike they US, much of Europe developed this style of signal instead of changing to the positional lights and traffic light style.

The earliest semaphore signals, using arms, were very simple in design. One example of an 1880’s semaphore utilized two paddle shaped arms with squared ends: one arm was colored RED and positioned to move in the lower right quadrant; the other was WHITE and operated in the lower left quadrant. The term quadrant represents a position from pointing almost straight down and up to a horizontal position to the left or right of mast (pole) that they are mounted on. Typically, there were three aspects to be displayed:

Stop – RED arm horizontal and WHITE arm down.

Clear – WHITE arm horizontal and RED arm down.

Signal Inoperative – RED and WHITE arms in the down position.

I am sure that there were other configurations and colors, but that will be a topic for another time. The present research provided this information.

By 1900, the addition of lighting became typical and complimented this two-arm semaphore to provide improved operation and visibility. In this configuration, only the red arm was movable and included a red and green lens; the white arm was fixed in the horizontal position. One lamp was placed on the left side of the mast or pole and the light would shine through a hole in the white arm and illuminate the red or green lens as the red arm was positioned. This provided three aspects to the engineer and crew:

Stop - Red arm horizontal with RED lens illuminated.

Caution – Red arm lowered 30 degrees from horizontal with GREEN lens illuminated.

Clear – Red arm lowered 60 degrees from horizontal with the no lens illuminated; the white light from the lamp was exposed thru the hole in the white arm.

About this same time, circa 1890, the illuminated two-position semaphore began to appear on some railroads. Again, its use and information was limited compared to today’s standards, but was adequate for the time. As in the previous example, the lamp was located on the left side of the mast and the red lens of the arm would cover the lamp lens in the horizontal position. There was only one lens at the end of the arm and the arm now had a white band across the arm. This band was about 12” in from the end of the arm. The rear of the arm was colored white and the band was black. The arm was typically measured 5’ from the pivot point to the end while the lens end was only long enough to cover the lamp. This provided the following two aspects:

Stop – Red arm horizontal with RED lens illuminated.

Clear – Red arm lowered 45 degrees from horizontal and the white light visible.

Up to this time, the signals were mostly manually operated and train spacing was based on time separation. The signal operator would set the signal as the train entered the block or route. After a defined time, as set forth in that railroads “rules,” the operator would reset the signal to indicate Clear and hope for the best. Each crew was then responsible to protect the train with flags, flares or other manually placed devices located a prescribed distance behind the train that would provide sufficient stopping distance. Oncoming traffic was typically held until the scheduled train passed the meeting point. Thus, one can understand the importance of running by the timetable.

Next time, in addition to the Banjo dimensions, the discourse will cover the introduction of the “basic track circuit,” invented by Dr. William Robinson in 1872, which provided for the automatic operation of the signal by the train. This accommodated the increase in traffic volume and growing safety issues.

to be continued...

Signals  (Part 14)
by Craig Ingham
(June 2002)

Ah yes! I recovered from the severe case of CRS that was previously reported. Now our Banjo signal will be discussed in further detail.

The Banjo signal device is shaped simply as a banjo with a short neck. Our signal is constructed of vertically aligned tongue-and-groove beaded 1 x 2 inch milled lumber. The “beading” is nice. A single, formed 18-gauge sheet metal piece wraps around the circumference, beginning and ending at the bottom of the base. It is basically a 43-inch diameter circle sitting on a 12-inch high by 12-inch wide base and the depth (front to back) is 9-inches. With that picture in mind we can position the details. Hopefully, someday, when I am resting, a detailed drawing can be created and provided.

First, we will discuss the “window” positions on the front side that the engineer would see. On the vertical centerline, measuring down from the top 5-5/8 inches is the center of a 6-3/4 inch diameter opening with a clear glass lens. This window provides for an illuminated colored display of RED or GREEN, which will be detailed later.

On the same centerline, 27-1/2 inches from the top, is an 18-inch diameter opening with a clear glass lens. This window provides the colored daylight presentation, either RED or WHITE (no color), which will be detailed later.

Still on the same centerline, 55–1/2 inches down from the top, is the bottom of the base. This is where one must get out his trusty “French curve” drafting tool, or “fillet” (steak) command on your CAD program, and “marry” the 43-inch diameter “face” with the 12-inch high base. I did not take the time to determine the radius required for this, but it is relatively gentle.

Second, the rear side of the Banjo is of the same outer dimensions as the front side. This side provides for access to the “innards” for maintenance and for the illumination lamp mounting. The upper hole is dimensioned like the opening on the front but does not have a lens. Just below the opening is a standard mounting bracket for mounting a single lens kerosene lamp (similar to those used on car sides for marker lamps). At some point in time, the illumination was probably changed to electric lamps with similar mounts. Imagine the signal maintainer having to go out each night and when visibility was below the standard, as established by the specific railroad, to each signal and climb the access ladder to fuel and light the lamp. Probably a miserable task when it was raining, snowing or freezing!

Directly in line with the larger front opening is an access panel that is 27-inches wide by 30-inches high overall. The panel bottom is shaped so that the horizontal dimension is 13-inches with angled cuts from each end to a vertical point on the height 7-1/2 inches up. This panel is hinged on the left side of the vertical, as viewed from the rear, and a latch is provided on the right side. Typical of the craftsmanship exhibited by the railroads in that time period, the alignment of the panel’s tongue-and-groove pieces matched that of the rear façade. There is also a matching overlap in the opening and the panel so as to provide a seal from the natural elements.

Third, the display colors previously mentioned are incorporated as parts of a counterweighted assembly and include three disks as well as an open frame Hall electro-magnetic actuator (solenoid to many of us). There are two RED disks, with diameters of 16 inches and 6-1/2 inches. A third disk is GREEN and is 6-1/2 inches. The larger disk has a silk material stretched over a hoop and stitched to the round wire form. The two smaller disks are a transparent material, probably celluloid, that is attached to the round wire form. The arrangement places the RED disks at 180 degrees from each other with the smaller at the top, or 0 degrees. The GREEN disk is positioned at 90 degrees clockwise from the top and is offset by the counterweight. I did not determine the weight of the counterweight. The arrangement is set so that with no power, the electro-magnetic actuator not energized, the RED disks are positioned vertically with the small disk displayed at the top opening and the larger disk displayed at the larger middle opening. The small GREEN disk is hidden from view. The counterweight holds the assembly in that position. When the actuator in energized, the assembly rotates counter-clockwise to position the small GREEN disk at the top opening and no disk at the larger opening. The inside of the rear is painted WHITE to provide a visible Clear indication during daylight operations.

The actuator was mounted to the inside of the rear such that the rotational axis point was centered at 11-1/2 inches up from the center of the larger lower opening and 8-1/2 inches down from the center of the smaller upper opening. A 5-1/4 inch rod connected the small RED and GREEN disks to the pivot point and a 3-1/2 inch rod connected the large RED disk to the pivot point. OOPS! I did not measure the rod length for the counterweight.

Fourth, the arrangement for mounting on our Banjo head on the mast is a 2-inch metal angle, ¼ inch thick, with clearance holes for bolts to attach to the base. The head would be mounted either atop a mast or on a supported plate, like a deck, that was extended off the mast. The angle pieces are 9 inches long for the sides and 12-1/2 inches long for the front and rear. The 9 inch angle pieces have two clearance holes, on 7-inch centers, for each flange of the angle; four holes per piece. The front and rear angle pieces have two clearance holes on 6-1/2 inch centers. AHAH! Another measurement I forgot; the clearance hole diameter! Probably ½ inch diameter.

Additional information:
The voltage to energize the Hall electro-magnetic actuator is probably very low: between one and three volts. If I recall correctly, ours actuated when a “D” cell was applied; this must be checked again to be sure. Typical track circuits functioned in that voltage range; specific voltages varied to some degree based on the ballast material and the influence of moisture; too much voltage resulted in shorts or false detection. This will be a subject for a future segment.

Originally, a “gravity battery” probably powered our signal. A “gravity battery” is the glass jar type; two dissimilar metals in an acid mix in a glass jar. We have a few in our archives (defined by some as being buried under some other old junk). More on that at another time.

Our signal appears to have been a “home” signal located at the top of a multiple head mast or as a single head. This assumption is based on information from several pieces of reference material. Had it been a “distant” signal, the colors would probably have been either GREEN and WHITE (CLEAR) or YELLOW and WHITE (CLEAR). I have yet to find something from the Reading Company that specifically defines this. It is about time to check into the “data bank” at the RCT&HS.

When this relic is returned to a “like new” condition, a major decision must be made. Where do we safely display and operate it? Suggestions are welcome.

This article has become too long to address the subject of the “basic track circuit,” invented by Dr. William Robinson in 1872. Therefore, I will reassign that subject to another issue.

to be continued... 

Signals  (Part 15)
by Craig Ingham
(October 2002)

I am going to keep this article very short in order to provide room for Open House information and schedules.

There is a major correction to the Banjo Signal information that I felt was important to cover. The construction of the face and rear panels is two-ply. The previously described construction is built over a series of boards laid on a horizontal plane while the outer layer is on a vertical plane. I am assuming that this was done to provide a stronger assembly and prevents warping.

I haven’t had a chance to get the missing measurements so that information is still on hold. In fact, with all the repair work and preparations for our events, the restoration of the signal has slowed to something less than a crawl. It seems strange to say it, but we are waiting for winter so there is time to renew some of our restoration projects. If the winter is cold enough, we will have an excuse to stay inside and get some of the “fun” work done. All this routine, necessary property maintenance, and upkeep certainly interrupts the accomplishment of the “fun” things.

I’ll close for now and start to build the 16th installment.

to be continued...