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(2014-03-19)  
North-American, British and French terminology.

The evolution of rail transport in the New World was largely independent fromits counterpart in the British Isles and the rest of Europe. Some of the resulting differences in terminology are summarized by the following table:

(2014-03-16)  
The model railroad scales are best expressed in millimeters to the foot.

This strange convention involving two competing systemsofunits came naturally to early trainmodelists  (in Britain)  who started usingreadily available metric rulers to build models of prototypes measured in feet...

The nominal scale of a minature train applies to all parts of the vehicles,with the possible exception of the wheels and the paramount trackgauge.

The reference to the foot as the prototypical length is sometimes omittedand we may talk about the 7 mm scale  (O scale, 1:43.5) 4 mm  scale  (OO scale, 1:76.2)  3.5 mm scale (HO, 1:87.1).

To translate a millimeter specification into a scaling factor, recall simply that afoot is exactly  304.8 mm. This gives the followingdecimal expressionsfor the HO (3.5 mm) and OO (4 mm) scales,respectively:

304.8 / 3.5   =   87.0857142            304.8 / 4   =   76.2

• The HO scaling factor is 87.0857... (often rounded to 87.1 or 87).
• The OO scaling factor is exactly 76.2  (often rounded to 76).

Upon standardization, it was decided that both scales would use the tracksthat are technically accurate for the HO scale only  (they are thus 12.5%undersized for OO models of actual trains).

The 8/7 ratio between the two linear scales means that the OO scale correspondsto volumes that are larger than HO volumes by the cube of that ratio,which translate into a  49.3%  increase in bulk.

Increasingly, the HO scale is simply referred to as  1:87 and models are produced to this precise specification, which isvirtually indistinguishable from the original definition of  3.5 mm to the foot (the difference is 0.1%).

Next up are the S and O scales:

• The S scaling factor is exactly  64  (³/₁₆''  to the foot).
• The O scaling factor is exactly  48  (¼''  to the foot)  in the US. In the UK and in France however, the O scale is still defined as  7 mm  to the foot, which isequivalent to a scaling factor of about  43.543  (usually rounded to  43.5). This "7 mm scale" is exactly twice the HO scale. An intermediate ratio of 45 is used in Germany and Russia.

(42 in) / (56.5 in / 64)   =   5376 / 113   =   47.575221238938053...

Historically, the O scale  (7 mm to the foot)  predated the HO scale. This explains the latter acronym  (it used to be called "half-zero"). The O scale can be denoted either by the letter "O" or the digit "0" (zero). Likewise HO (two letters) and H0 (trailing digit) are synonyms.  The arcana continues:

• The scaling factor for "#1" is   32  (³/₈''  to the foot).
• The H scaling factor is  24  (½''  to the foot).
• The G scaling factor is  22.5  (¹⁶/₃₀''  to the foot).

Minor discrepancies in the scale of model trains have little conseqences,as long as they're precisely engineered to operate on the same tracks. Early on, manufacturers had to settle on a limited number of track gauges.

This process parallels the gauge standardization which had occurred earlierin rail transportation, driven by the need for interoperabilty of rolling stock,as summarized in the next section.

(2014-03-17)  
Brunel'sbroad gauge of  7' ¼'' (GWR)  lived from 1833 to 1892.
60% of the lines worldwide are in the standard gauge of  4 ft 8½ in.

By definition, the gauge of a railroad track is the inner spacing between the two rails  (normally, the term gauge denotes the distance between the rails but it's sometimes used to refer to the spacebetween the rails, sometimes called the 4-foot way in British railway jargon).

In metric terms, thestandard gaugeis exactly  1435.1 m  (often described as  1435 mm,which messes up the exact arithmetic without any benefit at all).

The second most common gauge today is the Russian gauge which was originally specified as  5 ft  (1524 mm). Finland still uses that original definition but the Russian railways have adopteda rounded metric definition of  152 cm  (1520 mm). For regular traffic, both definitions are compatible but high-speed trains havetighter tolerances... On 12 December 2010,  the Allegro high-speed trainwas inaugurated between Helsinki (Finland) and St. Petersburg (Russia) with Karelian Trains (Class Sm6)  of the Pendolino  family manufactured by Alstom. It's actually built for a nominal gauge of  1522 mm. So are the new high-speed tracks compatible with the Russian gauge. It's thus best to consider  1522 mm  to be the oneand only modern definition of the Russian gauge  (existing tracks arewell within manufacturing tolerances of this nominal definition).

Many narrow gauges are primarily used for short hauls in industrial settings. Some of them are much more widely used.  Most notably:

• The 3-foot narrow gauge  (914.4 mm)  in North America.
• The metric narrow gauge  (1000 mm)  in Europe.
• The Kyoki  or Cape gauge of  3 ft 6 in  (1066.8 mm)  in Japan.

The kyoki  gauge of 1066.8 mm is dominant in Japan, except for itsShinkansen high-speed lineswhich are in standard gauge  (1435.1 mm).

Australia also uses the Cape gauge of 1066.8 mm on most of its lines. Unlike Japan and despite the lesser stability of such narrow tracks,they're providing high-speed service on that same gauge. TheTilt train ofQueensland Rail is the fastest train in Autralia and the fastest train in the world on narrow gauge. Yet, its record speed of  210 km/h is far from what can be achieved on standard gauge  (the current record of 574.8 km/h was achieved on 3rd April 2007 by a five-car TGV "V150" double-decker, specially preparedfor speeds beyond 150 m/s,  or  540 km/h).

Yet, it's unlikely that the need for speed will ever resurrect Brunel's broad gauge  (2140 mm; slightly more than 7 ft)  last used bytheGWR in 1892. (The rare suffix "b7" is used by modelers to denote that gauge.)

(2014-03-17)  
The  16.5 mm  model gauge is used by  HO, OO, On30 or Gn15  models.

At the nominal HO scale of 3.5 mm per foot, standard gauge  (1435.1 mm)  would be 16.479666...mm,  which is normally rounded to  16.48 mm  or  16.5 mm. That's the standard track gauge for both HO and OO model trains.

(1 ft) / (3.5 mm)   =   3048 / 35   =  87.0857142  is the HO scaling factor.
1435.1 mm / (3048 / 35)   =  16.4796 mm  is the HO standard gauge.

At the OO scale of 4 mm to the foot, standard gauge accurately correspondsto the so-called EM-gauge of 18.333...mm, which is part of the Protofour (P4)  modeling standards at the 1/76.2 scale (pioneered by Joe Brook Smith and Malcolm Cross in July 1964).

At HO scale, the 3-ft narrow gauge is exactly  10.5 mm, which corresponds to the  HOn3  gauge, commercially availablesince 2010 from Blackstone Models (a division ofSoundtraxx created in 2004).

The popular N-gauge is only 9 mm; Pecois advocating the use of this for narrow-track modeling  (minework etc.) at the  OO  scale  (1:76.2)  next to standard  OO  track (16.5 mm)  and in sharp contrast with it. Dubbed  "OO9",  that use of a  9 mm  gauge would correspond to theunusual gauge of exactly  27 inches.

The practical minimum gauge for usefulrail transport is around 15 inches  (381 mm). Anything below that is considered a miniature  line.

The number 15 evokes very narrow gauges so strongly that the acronym Gn15  (G-scaled very narrowgauge) was coined as a generic term to describe their activity by the community of modelists whorun garden-sized model trains  (at typical scales between 1:48 and 1:20)  on HO tracks.

(2014-03-17)  
A type  of model trains is the combination of a scale  and a gauge.

Although modelers might prefer to have tracks and trains built to the exact same scale,they often settle for widely available miniature tracks whose actual gauge (the inner space between rails)  is only an approximationof the scaled down dimension of the actual tracks used by the ptototypes they are modeling at their chosen scale.

More than  80  different types of miniature trains are sufficientlywell-defined to have a recognizable standard designation (not all of those are supported commercially or by associations). To each such type corresponds a unique gauge and a unique scale. Thus, we may talk unambiguously about the HO gauge (nearly  16.5 mm  between the rails) or the HO scale  (3 mm/ft = 1:87.1). Likewise, the HOn3 gauge is 10.5 mm between rails.

A given gauge can be shared between many model types (which can operate on the same track layout if their loading gaugepermits, although thescenery may be out of scale). Conversely, models of the same scale can represent a consistent picture ofreality with vehicles of different gauges operating on different tracks in a single layout, if needed. The big picture is summarized by the table below  (a Numericana  exclusive).

In our table,  the model types in italics  or between parentheseshave little or no support, for a variety of reasons. For example, there are no prototypes with a gauge of 4' or 18'',which makes types ending with n4 or n18 utterly useless for modeling purposes.

Bold numbers,  for scales or model gauges, indicate values that are exact by definition. Likewise, bold model types  are those whose nominal gaugesare perfectly true to scale. For readability, some groups of prototypical gauges have been singled out with the color-coding  described below (i.e., standard , Cape/metric/yard  & minimal ).

Notes :

(*)    The scale corresponding to the Stephenson gauge for  HOn3 track (10.5 mm)  is called the track scale  for the model gauge of  10.5 mm:

1435.1 / 10.5   =   136.6761904...

Normally, the track scale of a widely available model gauge will be used by many professionaland amateur modelers.  The  1:137  is an exeption. It's apparently all but unused  by the modeling community. It happens to be nearly one tenth of SE scale (SevenEighth =⁷/₈'' to the foot):

12 / (7/8)   =   96 / 7   =   13.714285...

(**)   The interesting combination of the British OO scale  (4 mm to the foot, or 1:76.2) with  On3 gauge  (19.05 mm = ¾'' )  wouldresult in an  "OO19"  modeling standard where the gauge is merely 1.15% out of scale. This is currently unsupported  as a whole.

Instead, the P4 standard (OO scale with a prototypically correct standard gauge of 18.83 mm) and the  EM standard  (OO scale with  a -3.4% out-of-scale18.2 mm gauge,formerly dubbedEighteenMillimeter gauge) are both actively supported by the BritishEM Gauge Society  (EMGS) whose members re-wheel OO models to run on custom-built tracksusing their preferred gauge (instead of HO gauge or On3 gauge). They use  28 mm track  (28.084 mm)  when modelingBrunel's old broad gauge  (2140 mm).

Color-coding and prototypical gauge suffixes :

 Green highlighting  is for entries which are used to modelthe standard Stephenson gauge of  56½ in.  (1435.1 mm). When set in bold type,  the correspondance is an exact onewhich can be used to work out exactly  its nominal gauge or its nominal scalewhenever the table provides only an approximation while giving the true value (in bold)  for the other quantity (the gauge is 1435.1 multiplied by the scale and the scale is the gauge divided by 1435.1).

For example, the standard gauge at  S-scale  (1:64)  is actually:

1435.1 mm / 64   =   22.4234375 mm   (rounded down to 22.42 mm)

A more delicate case is the gauge shared by Sn3 (1:64) and the 3 mm scale (1:101.6) which is boldly defined  as 14.2 mm.  This would entail prototypicalgauges respectively equal to:

64 (14.2 mm)   =   908.8 mm      and      101.6 (14.2 mm)   =   1442.72 mm

The relative error with respect to the target gaugesof 914.4 mm and 1435.1 mm are only -0.61% and +0.53%, respectively. Nevertheless,such tiny discrepancies are sufficient not to award bold listings to either type. To put it another way, the perfect nominal gauges ought to be:

1435.1 / 101.6   =   14.125 mm      and      914.4 / 64   =   14.2875 mm

Whoever chose a  14.2 mm  gauge (commonly called "14 mm track") for both cases made a brilliant decision. Neither type of models is noticeably out of scale! As a bonus to British modelers, an OO scale model onthat gauge will represent the Japanese narrow gauge of  3½ ft just 1.4%  out of scale  (OOj or OOn3½). Likewise, the representation of  2-ft  narrow gauge at 1:43.5 scale  (O14)  using the same track is just 1.3% out of scale.

 Yellow highlighting  signals three common narrow gauges of similar sizes:

• American 3 ftgauge  (1 yd  =  914.4 mm)  denoted by an  n3  suffix.
• European meter gauge  (1000 mm)  indicated by an  m  suffix.
• Japanese kyoki  of 3'6''  (1066.8 mm). Suffix is  j  or  n3.5  or  n3½.

When such an entry appears in bold,  (which occurs for HOn3, OOn3, On3 and Fn3) it corresponds exactly  to the relevant prototypical gauge. Thus,  Fn3  entails the following exact scaling ratio:

914.4 / 45   =   20.32

Incidentally, the table allows you to retrieve indirectly the fact that HO scale is exactly 3.5 mm  to the foot  (:  start with the fact thatHOn3 gauge is exactly  10.5 mm).  Then, you can obtain the true nominal HO gauge:

1435.1 / (304.8 / 3.5)   =   16.47916 mm  (usually called  "16.5 mm")

 Red highlighting  is for extremely narrow gauges approaching the practicalminimum of  15 inches  (381 mm). The absolute minimum for modeling purposes is  14 inches (e.g., 45 mm track at 1:8 or 22.42 mm at 1:16).

At the opposite end of the spectrum are a few broad gauges which can be fairly well represented at popular scales using commercially available tracks (theRussian gauge, which is 6% above standard gauge, isn't one of them). Since most modelists prefer compact layouts for a given size of locomotives,the broad gauges are not nearly as popular as standard or narrow ones (they're identified by a "b" infix, in the upper triangle of the above table).

The Irish gauge  of  5 ft 3 in  (i.e., 63'' or  1600.2 mm)  is representedperfectly at a  2 mm scale  (1:152.3)  on standard 10.5 mm track  (Nb63).

The Indian gauge  of  5 ft 6 in  (i.e., 66''  or 1676.4 mm) can be well represented at various scale on available model tracks. Including  Nb66 which is only 0.2% out of scale at 1:160 scale on 10.5 mm track.

(2014-04-16)  
Live Steam & Diesel Model Railroading.

Thetable of the previous section can be extended to large scales:

Among larger scales, "F scale" is favored by those who are concernedwith matching the scale and gauge of a model train to those of a prototype.

In many cases, the dominant factor for outdoor train modelling is the gaugeof the tracks, which is rarely changed on a given property,because of the investment involved. Manufacturers will accomadate the installed tracks.

"E-scale" is what one manufacturer (RMI Railworks of Fresno, CA) callstheir preferred scale (1:3.2) for large ridable models. They are heralding this scale as "Estate", "Exceptional", or "Extreme"(it's exactly 30 times larger than the obsolete "E-scale" of 1:96,or oneeighth of an inch per foot, which has been superseded by HO). They offer rolling stock for a variety of gauges at that scalebut only up to 12 inches, which still corresponds to a prototypicalnarrow gauge of 38.4''.  To match the standard gaugeof 56.5'', a model at scale would have to use a gaugenearly 50% larger  (448.47 mm)  which isn't supported by RMI.

(2014-03-17)  
They are roughly  geometric progressions with inverse common ratios.

The system below is based on the numbers  32  and  45  whoseproduct  (1440)  is close to the standard gauge expressedin millimeters  (1435.1)  and whose ratio  (1.40625) is close to the square root of 2  (i.e., 1.41421...).

This regular system is clearly not very different from what's actually used in the industry and it showsthe result of natural market selection mascarading as engineering design over a century or so: From one gauge to the next, both the gauge and the scale are multipliedby the square root of  2  (for two steps, the gauge and scale are thus doubled). We're simply dealing with a straightforward geometric progression  here!

Never mind the lack of regularity of the historical naming scheme:

• T  is for Three milimeter gauge  (1440 mm / 480 = 3 mm). It runs!
• ZZ  is more exreme than Z  (1440 mm / 300 = 4.8 mm).
• Z  (last letter) was heralded as the ultimate in miniaturization in 1972.
• N  is for Nine milimeter gauge  (1440 mm / 160 = 9 mm) supersedingOOO  (triple O) considered the ultimate in miniaturization in 1964.
• TT  is for TableTop  (its 12 mm gauge at scale 1:120 is 1440 mm).
• HO  wasHalf the originalO scale(nowS7: 1:43.5 on 33 mm track).
• S scale
• O scale was called "zero" because larger scales had positive numbers.
• H scale stands forHalf-inch  (namely, 1:24 scale).
• F scale stands forFifteen-millimeter scale  (exactly  1:20.32).

(2014-03-17)  
The code  is the rail height in thousands of an inch (Code 100 = 0.1'' ).

For HO scale: C110   =   2.8 mm  (old Jouef track). C100   =   2.54 mm  (common track). C83     =   2.10 mm  (American scale, Kato). C75     =   1.90 mm  (British fine scale).   C80 and C55 are commonly used for N-gauge.

(2014-03-23)  
This alloy is also misleadingly called nickel-silver  (it contains no silver).

Maillechort  is actually analloy of copper, zinc and nickel. It is to brass  (i.e., copper-zinc alloy)  what stainless steel is to iron, as the addition of nickel improvesthe resistance to corrosion  (lower-grade miniature rails are also available which are made from stainless steel).

Cu₆₂Ni₁₈Zn₂₀  (NS106)  is the most popular variant. It's sold as  Awa®, Nickeloid®, Silmet® or Spedex®. That's the "nickel-silver" used for premium miniature railroad track  (stainless steel is considered lower grade).

There's no silver at all in maillechort,but its early use as a substrate for silver-plated silverware had lead to severalmisleading commercial names,  including "nickel-silver", "new silver" and "German silver". Variants of the alloy may be given several other names in different applications, includingargentan, alpacca, ruolz and EPNS  (electro-plated nickel-silver).

Maillechort  was perfected in 1819 by Maillet  andChorier, two Frenchmen fromLyon who combined their own surnames to name the invention.

The one-euro coin consists of a rim of yellow maillechort  surrounding a whitecenter of cupronickel on a nickel core.  For the two-euro coin, it's the other way around (the yellow maillechort  is at the center).

Since 1728, maillechort  (nickel silver)  has been a popular choice for themanufacture of musical instruments,although it's now less prestigious than it once was. Since 1970 or so, the top instrument makers have been returning to solid silver or goldexclusively for the metal parts of their best bows.

(2014-03-21)  
The spacing of railroad ties  (railway sleepers).

The French called travelage  the number of cross tiesper unit of track length; the French standard calls for  1666  ties per kilometer.

(2014-04-16)  
Properlightingat a given scaling factor  s  (e.g., s = 87  for HO).

In a finely scaled model, lighting should be properly scaled as well. The basic physics of scaling light is very simple but it's unfortunately all butignored by most modelers, which may lead to gross misrepresentations...

In the US, the Federal Railroad Administration (FRA) setsthe standards (we've corrected their utter disregard for the plural form of "candelas").

On Union Pacific locomotives, the headlights are 200 watts each and the ditch lights are 350 watts each. The candela rating depends on the efficiency of the conversion from radiant to luminous power (watts to lumens)  and the focusing of light by the headlight optics  (lumens to candelas).

On the other hand,the lighting of passenger cars comes from nondirectional sources (ordinary lightbulbs)  whose total luminous power is measured in lumens  (lm). To model such a light source, you must determine the lumen rating  L for the prototype and work out a scaled equivalent with thetechnology you're planning to use in the model (LED or incandescent light bulb). The following examples might be helpful for guessing that data:

Light source	Luminous power
60 W  incandescent light bulb	600 lm

At a distance  d,  the luminous flux received by the retina of the observer is inverselyproportional to the square of  d.  When looking at the corresponding light sourceon the model, we should have the impression that its distance is  s.d. Therefore, its lumen rating should be :

L / s²   =   L / 7600   for an HO model
(L/5800 for OO,  L/4000 for S,  L/2000 for O,  etc.)

To provide properly scaled lighting inside a passenger car, you should firstdetermine the total lumen rating inside the prototype. Divide that by the above reduction factor and find a way to match that rating withwhatever lighting technology you choose  (LED is probably best,especially if you use the newer white LEDs without the blue tint of the previous generation).

I just bought  (on e-Bay, for $20)  two vintage trois-pattes SNCF passenger cars by Fleischmann  ("probably" #U371 1442) with electrical contacts on the axles, but no working lights. A perfect opportunity to do the job right...

One of my favorite electronic components is the LM317 voltage regulator which comes in3-pin packages similar to transistors.  Standard devices can supply up to  1.5 A butFairchild makes a low-power versionin a small TO92 package (the LM317LZ) which can deliver up to  100 mA.

(2014-03-16)  
HO and OO model trains may share the same layout  (at different times).

Permanent layouts with detailed scenery are an essential part of the hobby. Bachmann originallyentered the model train field by providing injection molded plastic models of buildings,under the brand Plasticville®U.S.A.

Running HO and OO models at the same time is not recommended at allbecause of the blatant scale difference when the trains are side-by-side.

However, the same layout could accomodate both HO and OO model trainsat different times.  If that's the intention,then it's best to minimize the discrepancy between the trains and thescenery by choosing for the latter an intermediate scale (sometimes dubbed HO/OO)  equalto the geometric mean of the HO and OO scale, namely:

304.8 / sqrt (3.5 x 4)   =   81.46...

The resulting 7% scale mismatch so entailed is hardly noticeable. However, because HO is so dominant, precise scenery is usually designed at the 1:87 scale,which is 12.5% undersized for OO models.

It's also possible to use OO figurines in the foreground and HO decorations in thebackground to create the illusion of a greater depth of field (forced perspective). The eye is especially sensitive to the size of human figurines;if background figurines are smaller, distances appear larger than they are.

(2014-04-16)  
Never cast a shadow on a flat backdrop.  Magic of mirrors and lighting.

The backdrop is a key element of a scenery. It represent scenery elements so distant that they can be painted on arelatively nearby wall while preserving the illusion of true perspective.

That illusion of perspective, however, is immediately and utterly desroyedif a scenery element from the foreground  (a tree or a building, say) is allowed to cast a shadow on the wall! This is the single most widespread mistake among modelersand most of them are not even bothered by it on the final layoutwherever it happens.  Neither are the spectators, becausethey don't believe in the illusion in the first place (they see the room and the celling and know that the sky is not real on the first place).

However, when you make a video of the layout, an otherwise perfect illusion can becompletely destroyed by such shadows which are then seenfor what they truly are:  mistakes.

Viewing your railroad World through a window...

For a confined layout which must be located along a "main" wall, you may want to simulatea window frame between two long horizontal pieces of wood (vertically aligned and decorated with the same trim). The lower one should extend slightly above the highest piece ofterrain occuring at the edge of the bench. The upper one will help create the illusion of the layout's "sky"beyond the window frame so created.

This upper frame can be extended into a narrow shelf to accomodatelighting fixtures for the layout and hide the "end" of its fakesky  (a bluish curved surface starting vertically at track level and endingsomewhat horizontally above that shelf, hidden from the eyes of little childrenat bench level). This opens up the possibility of artistic upgrades,like the projection of moving clouds, simulated sunrise/sunset or even nightsky.

How to avoid unrealistic shadows on the painted backdrop :

Distracting shadows don't occur when the light rays are parallel to the back wall, or nearly so. If a shadow hits the wall, it should be hidden from the spectator by some foreground element.

Another technique is to have scenery elements touch the wall  (possibly with some partof the element painted on the wall itself).

Finally, if all else fails, you can "erase" the shadow by illumating it "just right"with localized lighting  (possibly using a few bright LEDs on the backside ofthe offending scenery element).  Such a technique is so unexpected by the brainof the spectator that is will create a strong illusion that the wall is not even there. It's very delicate to do right, though.  An artform in itself.

The magic of mirrors :

One powerful technique to create an illusion of space at midrangeis through the use of mirrors.  We have all seen how small restaurants may appearmuch larger by having the upper part of at least one of their walls mirrored up to theceiling.  This makes the ceiling look at least twice as large (possibly infinitely larger if two opposite walls are mirrored).

There are several ways mirrors can be successfully applied in a model train layout,using either large or small mirrors. Large mirrors will always remain fairly obvious but small mirrors canbe used in ways that fool the spectator completely... Both techniques require considerable planning to be effective.

If a large mirror perpendicular to the main wall is used,the tracks should be planned never to go too close to the mirroror be hidden from it by scenery elements. If at all possible, arrange things so that an object and its imageare never seen together  (especially for trains and other movingobjects).

For example, you may install a sunk track next to the mirrorwhich is never seen directly but whose reflection in the mirror ispartially apparent. This would give the impression of a double track with one track hidden from view. If that's the desired effect, watch the direction of circulation of the mirror image (if your layout is meant to be consistent with,say, trains running on the left of a double track). Any writing visible in the mirror should be painted backwards!

One great way to use small mirrors is to place themat nearly  45°  from the main wall. This can give the illusion of something beyondthat wall, obtained as the reflection of some hidden perspective,more or less parallel to the wall. A lot of planning must bo into this (it's safer to plan the surrounding scenery for the mirror,not the other way around).

Deep-Stairway Illusion

Another very specialized use of mirrors which I find interesting is to simulate depth forthe "subway" stairways of platforms  (when actual holes are ruled out). One example is the Butterfly Station Platform Sheltersin the Walthers Cornerstone Series  (HO-scale,933-3175are sold separately from the matching933-3094Union Station).  The roof over the platform will typically prevents thespectator from looking directly into the stairwell and discovering the trick (afirst-surface mirrorperpendicular to the stairs), The illusion only works if the slope of the stairs is exactly 45° with identical verticaland horizontal surfaces  (which is the case in the aforementioned kit,probably to prevent the assembly mistakes that a more realistic asymmetrical design wouldallow).  A tiny lightsource in the plane of the mirror can complete the illusion.

In most illusions involving mirrors, first-surface mirrors are mandatory. That's especially true for this deep stairway  illusion (you may also want experiment with lines parallel to the edge of the mirror,which will help hide its exact location, even to people who suspect its existence).

(2014-04-06)  
Knuckle couplers.  Loop and hook.

Z-couplers don't hook up on corners.

Athearn owns McHenry couplers. EZ-mate (Bachmann).

(2014-04-07)  
The maximum size of rolling stock.

Because railways were developped in Britain ahead of the rest of the World,the need for very large rolling stock was not yet anticipated at the time. As a result, the British loading gauge is very restrictive.

This is where the locution "six-foot way" comes from.

British outline.  German outline.

The Berne gauge defines a clearance enveloppe on a curve of  250 m  radius.

(2014-03-17)  
First, second, third and fourth radius  (R1, R2, R3, R4).

Various manufacturers of sectional track sell elements of curved trackwhich are pecified to cover a fraction of a full circle  (usuallyexpresses in degrees; if it takes n elements to build a full circle,then the bend of each element is  360°/n). The radius of that circle is measured with respect to the center of the track;each manufacturer proposes their own set of radii, as tabulated below (in millimeters).

Kato's Unitrack®  is based on a  24-inch  basic radius of curvature (609.6 mm, rounded to exactly 610 mm)  and a  60 mm center-to-centerspacing between parallel tracks.  Half a dozen curvatures are commercially availablein that system:

The standard Unitrack siding  (featuring parallel track 60  apart, center-to-center) entails a #6 turnout  with two compensator elements:  An R867-10  corrector curveand an  S149  (149 mm straight section). The straight part of the #6 turnout is equivalent to two S174The combined length of this assembly is

(2014-03-17)  
Distance between tracks to allow safe crossings of all trains.

6-foot way, bumper locking, overhang, big-boy.

In British railway jargon, the space between the rails of a track is calledthe four-foot way  and the space separating the outer railsof parallel tracks is dubbed the six-foot way. Those traditional terms are a poor indication of the width of those ways (roughly 5 ft and 9 ft, respectively)  but they can ne usefulin sorting out the function of each rail in a busy yard.

In modern times, the quantity of interest is the center-to-center distancebetween parallel tracks  It's equal to the width of the the afforementioned "ways"plus the width of 2 rails.

French tracks are ordinarily spaced 4.2 m  (4.5 m for high-speed trains) center-to-center, for straight segments.

At HO scale, 4.2 m becomes 48.23 mm.  However, for the layout to accomodateOO models, the distance must be at least 55.12 mm. The  4.5 m French high-speed standard becomes 59 mm at OO scale,which is probably a good design standard for straight tracks in alayout meant to accomodate HO and OO models.

On a curved track, rolling stock can protrude significantly inward and outward...

(2014-03-30)  
At the heel of a #N turnout of length N, the tracks are one unit apart.

In other words, the number rating of a turnout is the length it takes to achieve a unit offset. In US railroading, the rated speed of a switch  (in mph)  dependson its number:  It's about twice the number for moderately long turnouts  (#15 or #20) it's less than that for the sharper turnouts used in yards  (low numbers). The rated speed of very long turnouts  (#22 or more)  is more that twice their number.

The Russians rate their turnouts by giving the tangent of the crossing angle, which is simply  1/N.

N	Tangent	US speed		Russian speed
#15	1/15	30 mph	48.3 km/h
#20	1/20	45 mph	72.4 km/h

A few problems with modular track systems :

The lengths of the straight sections in the #5 and #6 turnouts of Bachmann's EZ-track systemare respectively  11½''  and  15½''. Both are packaged with a small  2¼''  additional piece ofstraight track which have an essential feature which isn't documented. The two tracks at the heel of those long turnouts are too close to mate withregular pieces.  However, the underside of short pieces feature two slanted groveson the side meant to meant with the turnout. You need two such pieces to use the turnout  (one ot them has to be purchasedseparately).  Soften the roadbed by bending back and forth two opposite groveson short pieces, then fold the roadbed inward  (you could cut it or break it bit youdon't have to).  So modified, the pieces can mate with the two tracks at theheel of the turnout.

Unless there's a matching turnout somewhere else in the layout,the length of its straight path must be compensated by short straight piecesfrom the EZ-track system (4½'' and 2¼'' pieces are sold in packs of four, and an assortedpack of 10 pieces is sold as #44592 which contains 5 sizes: ¾'', 1'', 1¼'', 1½'' and 2'').

(2014-03-21)  
What manufacturers ought to supply to allow interesting compact layouts.

Besides the long  curved elements described above,there should be long  straight elements of roughly thesame length. Turnout components are indispensable which allow a choice between a straightpath and a curved one  (in a left turnout, the curved path is to theleft of the straight one; it's the opposite in a right turnout ).

For compactness and flexibility, the straight and curved sections in standardturnouts are shorter than the standalone straight and curved long sections. Shorter elements must be supplied to accomodate the following layout requirement:

• Corrector curve  (turnout corrector).
• Compensator straight.

(2014-04-01)  
Positive potential applied to the right-hand rail produces forward motion.

This is the traditional way to control rolling stock in model trains. Unlike the mre recentDCC protocol, this allowsthe control of only one locomotive perblock, which canbe a severe limitation.

The nominal full-throttle  voltage is  12 Volts  (DC) but the motors are supposed to withstand up to  16 VDC.

(2014-03-17)  
A one  is a full squarewave lasting 116 ms. A zero  is 200 ms or more.

Except when it's in the process of rapidly switching its polarity,the voltage between the rails is always 14.25 volts  (nominal).

CV = Configuration values.

• EasyDCC by CVP.

(2014-03-29)  

(2014-03-30)  

(2014-03-29)  
Locating DCC equipment by monitoring changes in current.

In a track layout divided into electrically isolated blocks, the current supplied to each blockcan be monitored.  In analog (DC) mode, this merely tells whether something is on a given detection block  (and/or if something has moved from one block to the next).

With digital control (DCC) the command center can rapidly switch on and off a device (typically, the headlight of a locomotive)  and determine precisely on what blockthat device is located by sensing which block experiences a change in current.

This technique gives the appearance of two-way feedback communications (it looks as though a locomotive is telling its location to the command center). It's known as transponding.

For a computer to avoid collisions it's also important that all rolling stock draw at leastsome current to be detectable (at the very least, the first and last element of a train should do so). This is most easily accomplished by bypassing the isolation ring(s) in a metal wheelsetwith a resistor of no more than 15 k  (to draw a current on the order of 1 mA  or more).  This is done with eithera small surface-mount resistor or some resistive varnish  (containingtiny particles of graphite which come together and form a stable resistor as the varnish dries).

(2014-05-31)  
Open Local Control Bus  (OpenLCB).
Input "producers"  &  output "consumers".

The most popular cables for local area networks  (LAN) consist of four twisted pairs  (8 conductors) connected to two RJ45 jacks with molded plastic hooks ("RJ" stands forregistered jack;RJ45 jacks are also dubbed "8P8C" as they feature 8 positions and 8 conductors). Those cables are commonly known as Ethernet cables (they are used forEthernet over twisted pair,which has replaced thethick andthin coaxial versions of Ethernet). They come in several mutually-compatible grades  (known as "categories") according to the maximum data transfer rate they can support. The evolution of the various grades of those cables parallels the evolutionof Ethernet  (at times Ethernet innovations were advertised as workingwith existing cables, possibly by using more pairs).

For the undemanding specialized use discussed here, any grade will do,including old Cat3 or Cat5 cable  (which is very cheap).

Pictured at left is theTIA/EIAT568-B color-coding of such cables. Pair 1 is blue (pins 4 & 5) Pair 2 is orange (pins 1 & 2)Pair 3 is green (pins 3 & 6) Pair 4 is brown (pins 7 & 8).

To a telecommunication engineer, this standard may look rather crude. However, it can serve its undemanding purpose very well and more cheaply than more sophisticated alternatives (for example, Ethernet can use the full data-transfer capability of the 4 twisted-pairs and still carry"phantom" DC power via two different common modes on two different pairs).

Nevertheless, the OpenLCB/NMRAnet network is a bus just like Ethernet is. As such, it should be properly terminated  and grounded (without ground loops)  for trouble-free operation.

(2014-03-17)  
Reproductions of famous locomotives.

The 4-6-0 "Mogul" (10-wheeler, in US jargon).

(2014-04-11)  
Humble or prestigious passenger services.

SaysPhoebe Snow, About to go Upon a trip To Buffalo

"My gown stays white From morn till night Upon the Road of Anthracite."    Lackawanna Railroad  (1900)

The fictional character of Phoebe Snow  had been created by Earnest Elmo Calkins (1868-1964) to advertise the lack of dust generated by burning anthracite on steam locomotivesfor passenger trains,  compared to less clean forms of coal. The Sackawanna Railroad owned large mines of high-quality anthracite whose usefor civilian purposes was outlawed during WWI.  That put an end to the Phoebe Snow  campaign, which ended with a last poem:

Miss Phoebe's trip     Without a slip Is almost o'er

Her trunk and grip Are right and tight Without a slight "Good bye, old Road of Anthracite!"

So ended the campaign for the Road of Anthracite, which remained known as the Route of Phoebe Snow for many years.  (The slogan was most notoriously painted in whiteon the brown box cars designed in 1937).

As outlined below,  the name was vigorously revived for a few years in the Diesel era,just in time to inspire the American singer Phoebe Ann Laub  (1950-2011)  who adopted it asher stage name.  Her own fame as Phoebe Snow  reached great heightswith the hit song Poetry Man (1975).

Phoebe Snow diesel train  (The Phoebe) :

On 1949-11-15, a streamliner was inaugurated for passenger service between Hoboken NJ and Buffalo NY (396 miles, or 637 km, in about 8 hours on a daylight schedule).  This flagship diesel trainreplaced the aging Lackawanna Limited  premier train and was officially named The Phoebe Snow. The Erie-Lackawanna  Railroad abandonned the Phoebe Snow  name againon  1962-10-28 The train service itself was discontinued only a few years later,  in 1966.

Exreme Railways, by Chris Tarrant :

• Congos Jungle Railway.

(2014-04-14)  
Large detailed models built around miniature trains.

• Grand Maket Rossiya: Russian landscape, trains and automobiles.