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Final Answers
© 2000-2016   Gérard P. Michon, Ph.D.

Model Trains
Mathematical aspects of "the World's Greatest Hobby"

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Union internationale des chemins de fer  (UIC = International Union of Railways)
Association of American Railroads  (AAR).
Railway Technical Webpages  by  Piers Connors :  Wheels and Bogies.
Railways: History, Signalling, Engineering  by  James B. Calvert :  Turnouts.
Normes européennes de modélisme (NEM) by  MOROP  (founded in 1954).
National Model Railroad Association  (NMRA):   Trackwork for beginners
British Railway Modelling Magazine  (BRM)
Kalmach Publishing: Model Railroader.
Model Railroad Hobbyist magazine.
Model Railroad Trains (at About.com)
Collectors Weekly:  Standard Gauge Model Trains (Lionel 2¼'', 1909)

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Roco (Germany, 1960)   |   Walthers (1932)   |   Weaver (1963)
GarGraves Trackage Corporation (1940)   |   Peco  (track & scenery).
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Busch :  Accessories, models and scenery in HO & N scales.
List of manufacturers and publishers  catering to the model train community.

Blogs :

Keystone Crossings by Jerry Britton.  History of the Pennsylvania Railroad.
Nelson's N-Scale Site
Retailers :   Model Train Stuff (MB Klein, 1913)  |  Arnie's Model Trains (1975)  |  Trainz.com  |  HobbylinC  |  Caboose Hobbies  |  Spring Creek Model Trains  |  Switch Stand Train Shop  |  The Favorite Spot
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How-to Videos :

How to use an NMRA gage  from  Model Railroader  magazine.
Flash LED pair with NE555  by  Seddik Jendoubi  (railroad crossing signal).

Video Archives :

"L'arrivée d'un train en gare de La Ciotat" (1895)  by  Auguste & Louis Lumière.
Union Pacific (1939)  by  Cecil B. DeMille  (miniature trains by  Athearn )
Emile Zola'La bête humaine (1938)  by  Jean Renoir  with  Jean Gabin.
Kansas Pacific (1953, cinecolor)  by  Allied Artists,  directed by  Ray Nazarro.
Tapered wheels, not flanges, keep a train on track  by  Richard Feynman (1983)
The Darjeeling Himalayan Railway:  Soul of a 2 ft narrow-gauge train (1881).
LSB Trains in Nürnberg, Germany:  Factory tour (2005).
The Japanese Bullet Train: Shinkansen:  by  Richard Hammond  (2013).
How it's Made :   Locomotives  |  Train Wheels & Axles  |  Train Rails
Thermite welding  |  High-Performance Weld (HPW)

Modern Steam   |   Abner Doble (1890-1961)   |   André Chapelon (1892-1978)


Model Railroad  &  Miniature Electric Trains

(2014-03-19)   Small Lexicon of Rail Jargon
North-American, British and French terminology.

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

American EnglishBritish EnglishFrench
RailroadRailwayVoie ferrée, chemin de fer
Railroad stationRailway stationGare [de chemin de fer]
Railroad crossingLevel crossingPassage à niveau, PN
TreslePont à tréteaux, pont sur chevalets
Beam bridgeGirder bridgePont à poutres
Truss bridgePont en treillis
Junction Embranchement
Passing sidingPassing loopEvitement, voie de garage
StubDead-end sidingVoie de garage [sans issue]
TraverserTransfer tablePont transbordeur
 Sector plate 
TurntablePlaque tournante, pont tournant
Classification yardMarshalling yardTriage, gare de triage
Tie, crosstieRailway sleeperTraverse
Ties per mileSleeper densityTravelage
Continuous welded rail, CWR, ribbon railLong rail soudé, LRS
Rail joiner, joint barFishplateEclisse
RerailerRerail frog 
Derail [device]DerailerDérailleur
Hayes bumperBuffer stopButoir, heurtoir
Switch, turnoutTurnout, [set of] pointsAiguille, aiguillage
Moveable point frogSwingnose crossing 
  Prendre en pointe
Running throughTrailing-point movePrendre en talon
Switch stand Signal de position d'aiguille
Interlocking towerSignal boxPoste d'aiguillage
Switch yard control tower
Signal bridgeGantryPortique de signalisation
Water towerChâteau d'eau
Water columnWater cranePrise d'eau, grue à eau
Track panWater trough 
Coaling stationDépôt de charbon
Loading gaugeOutlineGabarit
Train, consistTrain, rame
Rolling stockRolling stockMatériel roulant [remorqué]
Running stockMatériel moteur [de traction]
EngineLocomotiveLocomotive, tractrice
Power carRailcar, motor coachAutomotrice, autorail
Switcher, shifterShunter, yard pilotLocotracteur
Car, railcarRailway carriageWagon
Passenger carCoach, bogie (India)Voiture, wagon à voyageurs
Compartment carCompartment coach Voiture à compartiments
Corridor carCorridor coach
Freight carGoods wagonWagon à marchandises
BoxcarGoods vanWagon couvert
GondolaOpen wagonWagon-tombereau
Hopper carTrémie, wagon-trémie
Autorack, auto-carrierCar transporterWagon porte-automobiles
Tank carTank wagonWagon-citerne
CabooseBrake-vanFourgon de queue, cambuse
Vehicle components
CowcatcherPilotChasse-obstacle, soc
AnticlimberDispositif anti-chevauchement
WheelsetEssieu [ferroviaire]
FlangeBoudin de roue, joue
Axle boxJournal boxBoite à graisse
Solid bearingJournal bearingPalier lisse
Rolling-element bearing, rolling bearingRoulement mécanique
Ball bearingRoulement à billes
Wheel truck, truckBogieBogie, boggie
TailgateTail boardHayon
Miniature trains
UncouplerUncoupling rampDételleur, découpleur

Rail Terminology   |   Lexique ferroviaire  by  Florent Brisou (1964-)

(2014-03-16)   A short history of the standard scales for model trains
The model railroad scales are best expressed in millimeters to the foot.

This strange convention involving two competing systems of units came naturally to early train modelists  (in Britain)  who started using readily 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 track gauge.

The reference to the foot as the prototypical length is sometimes omitted and 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).

Some such scales have branched out  (the O-scale became 1:48 in the US and 1:45 in Germany)  or they have been superseded.  For example, the  2 mm scale  (1:152.4)  has been replaced by the very popular N-scale  (1:160)  of exactly  1.905 mm  to the foot.

To translate a millimeter specification into a scaling factor, recall simply that a foot is  exactly  304.8 mm.  This gives the following decimal expressions for 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 tracks that 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 corresponds to 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 is virtually 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 is equivalent 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.
In Japan and Taiwan, a specific model gauge of  24 mm  is used to represent the Kyoki narrow gauge  of  3.5 ft  (Cape gauge)  at a nominal scale of exactly  1:44.45.  This model type is denoted Oj in the orient.  In the west, where 24 mm model track is virtually unheard of, the same effect can be achieved with standard S-gauge track at the American O-scale  (1:48)  since:

(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 earlier in rail transportation, driven by the need for interoperabilty of rolling stock, as summarized in the next section.

 George Stephenson 
 1781-1848 (2014-03-17)   Prototypical railway gauges, then and now.
Brunel's broad 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 space between the rails, sometimes called the  4-foot way  in British railway jargon).

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

On 2014-03-18, I took my late grandfather's vernier calipers to an abandonned (standard) branch line in Normandy and found the width of those French rails to be about 56.5 mm  Thus, the center-to-center distance between the rails is 1.4916 m.  and the total width of the track is about  1548 mm  (between the outer edges of the two rails).
I can't explain the numerical coincidence that gauge width is 56.5'' while rail thickness is 56.5 mm.  For this particular piece of French track, at least, the thickness-to-gauge ratio is thus  1 mm/in = 1:25.4.

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 adopted a rounded metric definition of  152 cm  (1520 mm).  For regular traffic, both definitions are compatible but high-speed trains have tighter tolerances...  On 12 December 2010,  the  Allegro high-speed train was 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 one and only modern definition of the Russian gauge  (existing tracks are well 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 its Shinkansen high-speed lines which 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 track, they're providing high-speed service on that same gauge.  The Tilt train of Queensland 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 prepared for 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 by the GWR in 1892.  (The rare suffix "b7" is used by modelers to denote that gauge.)

A History of Track Gauge  by  George W. Hilton  (Trains magazine, May 1, 2006).
How the South changed the gauge of 11500 miles of track in 2 days   (in 1886)  and got it wrong by ½''
Mixed-gauge model  representing Lelant station, on the St Ives branch (1888-1892) in West Cornwall.

(2014-03-17)   Model gauges
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 corresponds to 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 available since 2010 from  Blackstone Models  (a division of Soundtraxx created in 2004).

The popular N-gauge is only 9 mm;  Peco is 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 the unusual gauge of exactly  27 inches.

That rare Welsh gauge of  2 ft 3 in  was used in a slate quarry line opened in 1866 which is preserved since 1951 in the Talyllyn Railway, which still runs the original #2 Dolgoch locomotive and the engines #3 (Sir Haydn) and #4 (Edward Thomas) rescued from the nearby  Corris Railway (1859-1948)  which once inaugurated  27'' tracks with horse-drawn wagons.  The Corris Railway reopened to passengers in 2002 and they are now constructing another 27-inch gauge locomotive based on the old design.
Besides  Talyllyn  and  Corris,  only one other extant  27''  railway has been reported, namely the "funicular" of the  Yorkshire Mining Museum  which opened in 1988  at the site of  Caphouse Colliery,  adjacent  Hope Shaft  in Overton, near Wakefield  (that museum has been known as the  "National Coal-Mining Museum for England",  abbreviated  NCM or  NCMME,  since 1995).  However, one narrow-gauge enthusiast had only one 30'' railway to report after his recent visit to the site  (either that or he misjudged the gauge by 3 inches).

The practical  minimum gauge for useful rail 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 narrow gauge) was coined as a generic term to describe their activity by the community of modelists who run garden-sized model trains  (at typical scales between 1:48 and 1:20)  on HO tracks.

(2014-03-17)   A Synthetic View of  All  Types of Model Trains
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 approximation of 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 sufficiently well-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 gauge permits, although the scenery may be out of scale).  Conversely, models of the same scale can represent a consistent picture of reality 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 parentheses have 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 gauges are 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 ).

Types of model trains   (some extremely rare ones appear in italics).
ScaleGauge  (inner distance between railheads, in mm)
 3 4.86.5910.51214.216.48 19.0522.423245
 1:300 ZZ
 1:220ZjZ Zb7
 1:160 Nj
N Nb66
 1:152.42 mm Nb63(Nb6)Nb7
 1:120  TTjTTn4TT TTb66
 1:101.6TT3n3TT3j TT3 3 mm TT3b66
 1:87.0857 HOf HOeHOn3 HOj(HOn4) HO HOb66HOb7
 1:76.2OO9OOn30 OOn3 (OOj)OO(**) OOb66
 1:64(Sp) Sn2n Sn2w Sn30 Sn3(Sj)(Sn4)S Sb7
 1:48  Coarse (US)O9 On30On3 (Oj)¼'' Ob7
 1:45  UnifiedOe  (Om)O
 1:43.5  Fine (UK)On18O12 O14O16.5  7 mm
 1:32 Gauge-1 track scale  #1p #1n18#1n2 #1m#1
 1:29 G-Scales #2p Gn15
 1:24US (Hj)
 1:22.5LGB Gm
 1:20.32 F   =   Fifteen    =   15 mm / ft  Fn15 Fn18Fn2Fn3
Big Scales  1:19.05SMp 16 mm
 1:13.714285 SE *
Gauge:  3 4.86.5910.51214.216.48 19.0522.423245
Other gauges not included in the above:   7 mm gauge:   HOn2 represents 2-foot narrow gauge at HO scale.
The 18.2 mm (EM) and 18.83 mm (P4) gauges are supported by the EMGS  (see below).
12.7 mm gauge:   On2 represents 2-ft gauge at the scale of 1:48 in the US  (Maine "two footers").
24 mm gauge:   In Japan, Oj represents Kyoki gauge  (3.5 ft)  at 1:44.45.  Would also do nicely for HOb7.
Obsolete scales:   1:152.4   OOO  (2 mm)  superseded by N (1:160) survives in Japan as N (1:150).
1:96   E-scale  (Eighth inch)  was superseded by HO.  It's also very close to TT3 (1:101.6).
Other names: The suffix "f" (Feldbahn) can be replaced by "i" (industrial).  HOj is called HOm in Europe.

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 professional and 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  (Seven Eighth = 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'' )  would result 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-scale 18.2 mm gauge, formerly dubbed Eighteen Millimeter gauge)  are both actively supported by the British EM Gauge Society  (EMGS)  whose members re-wheel OO models to run on custom-built tracks using their preferred gauge  (instead of HO gauge or On3 gauge).  They use  28 mm track  (28.084 mm)  when modeling Brunel's old  broad gauge  (2140 mm).

Color-coding and prototypical gauge suffixes :

 Green highlighting   is for entries which are used to model the standard Stephenson gauge of  56½ in.  (1435.1 mm).  When set in  bold type,  the correspondance is an exact one which can be used to work out  exactly  its nominal gauge or its nominal scale whenever 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 prototypical gauges 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 gauges of 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 on that 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 ft gauge  (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  (HINT:  start with the fact that HOn3 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 practical minimum 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  (the Russian 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 represented perfectly 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.

Chemins de Fer du Calvados (600 mm gauge).
Wikipedia :   G-gauge (45 mm)   |   Rail transport modeling scales  (List with NEM suffixes)   |   Track gauge
Track specifications enforced by  CN  (Canadian National Railway Company, created June 6, 1919)
Associations :
Train Collectors Association (TCA, US 1954)  and the  National Toy Train Museum (Strasburg, PA)
The Train Collectors Society  (TCS, UK)   "Any make, Any gauge, Any age".
Gauge 0 Guild (1956)   |   Corwall '0' Gauge Group
Broad Gauge Society (BGS, UK 1980)   |   GWR broad-gauge locomotives
National Association of S Gaugers (NASG, US)   |   S Scale Model Railway Society (UK, 1946)
EM Gauge Society  (EMGS, UK).  Using the 4 mm/ft (OO) scale with a good (18.2 mm) or perfect (18.83 mm) model gauge.
The Three Millimetre Society (UK, 1965)   |   Suppliers: 3 mm/ft Scale Model Railway = 3SMR
Forum discussions :   Model Railroad Scale & Gauge Variations (2014-01-01)

(2014-04-16)   Large-scale model and ridable miniature trains
Live Steam & Diesel Model Railroading.

The table of the previous section can be extended to large scales:

Unused types appear in italics.
ScaleGauge  (in mm)
448.47 609.6
 1:64 Sb7
 1:48 ¼'' Ob7
 1:45 O
 1:43.5 7 mm
 1:32 #1m#1
 1:29 #2n3  
 1:24 (Hj)
 1:22.5 Gm
 1:20.32 Fn2Fn3F
 1:19.05 16 mm
 1:16 ¾''
 1:13.7 SE * SEn3
 1:12 #4p1''
 1:11.3 #5p#5f
 1:10 #6p
 1:8 #7p #7
 1:4  Qm  Q
 1:3.2   En3 E

Among larger scales, "F scale" is favored by those who are concerned with 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 gauge of 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) calls their 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 one eighth of an inch per foot, which has been superseded by HO).  They offer rolling stock for a variety of gauges at that scale but only up to 12 inches, which still corresponds to a prototypical narrow gauge of 38.4''.  To match the standard gauge of 56.5'', a model at scale would have to use a gauge nearly 50% larger  (448.47 mm)  which isn't supported by RMI.

 Come back later, we're
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What is F scale?   by  Cumberland Model Engineering.
Roll Models, Inc.  RMI Railworks  "E scale" (Fresno, CA).

(2014-03-17)   The main sequence of commercial scales and gauges
They are  roughly  geometric progressions with inverse common ratios.

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

A regular approximation to the actual system of model train gauges
NameZNTTHOSO#1 #33.5''5''7''10''
Gauge/mm55/8811¼1622½ 3245 6490128180256
Scale1:2561:1801:128 1:901:64 1:451:32 1:22½1:161:11¼ 1:81:55/8

This regular system is clearly not very different from what's actually used in the industry and it shows the 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 multiplied by 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) superseding OOO  (triple O) considered the ultimate in miniaturization in 1964.
  • TT  is for  Table Top  (its 12 mm gauge at scale 1:120 is 1440 mm).
  • HO  was Half the original O scale (now S7: 1:43.5 on 33 mm track).
  • S scale
  • O scale was called "zero" because larger scales had positive numbers.
  • H scale stands for Half-inch  (namely, 1:24 scale).
  • F scale stands for Fifteen-millimeter scale  (exactly  1:20.32).

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

wheelset  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.

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(2014-03-23)   Premium miniature rails are made out of  maillechort.
This alloy is also misleadingly called  nickel-silver  (it contains no silver).

Maillechort  is actually an alloy 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 improves the 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).

The NS106 alloy was selected for its durability and its mechanical properties, not for its conductivity  (it's 16 times worse than copper but still twice as good as steel).  However, the lack of surface oxidation of nickel-silver rails tend to reduce or eliminate sparking.
One potential advantage of the poor conductivity of NS106 is that miniature rails could be welded electrically  (EWR or flash butt welding) like real rails are, to form a strong continuous welded rail  (CWR)  or "ribbon rail".  Modelers have shunned that technique in favor of soldering  (which is adequate for electrical contact).

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

Adding nickel to a copper alloy  (brass)  decreases its conductivity.
MetalISO (by weight) ConductivityNotes / typical uses
CopperCu58  106 S/mInternational annealed copper standard
BrassCu Zn > 13 106 S/mCopper-zinc alloys  (22-28% IACS)
NS101 Cu46Ni10Zn42Pb25   106 S/mMachining, decorative engraving.
NS103Cu63Ni10Zn27 Slightly yellow.  Cold-working.
BronzeCu Sn > 4 106 S/mCopper-tin alloys
NS104Cu64Ni12Zn244   106 S/mElectrical and spring applications.
NS106 Cu62Ni18Zn203.5 106 S/mPolishes well.  Resistant to wear.
NS109Cu60Ni25Zn153   106 S/mWire-wound resistors (?)
T302Fe74Cr18Ni81.45 106 S/m Austenitic stainless steel

Maillechort  was perfected in 1819 by  Maillet  and Chorier, two Frenchmen from Lyon who combined their own surnames to name the invention.

The one-euro coin consists of a rim of  yellow maillechort  surrounding a white center 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 the manufacture 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 gold exclusively for the metal parts of their best bows.

Smiths HP   |   Goodfellow   |   Nickel Silver Info  from  Shinwon Metal Co., Ltd.
The Nickel-Silvers  by the Copper Development Association (1965).  NS101 & NS102 are called "nickel brass".
Les maillechorts  by the "Centre d'information du Cuivre, Laitons et Alliages" (a Copper Alliance Member).

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

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

 Come back later, we're
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(2014-04-16)   Scaling Light  (cd for headlights, lm for car interiors)
Proper lighting at 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 but ignored by most modelers, which may lead to gross misrepresentations...

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

The FRA requires that the locomotive headlight (steady burn) used for road service have a luminous intensity of at least 200 000 candelas.  The headlight light focus angle in the horizontal plane in relation to the centerline of the locomotive must illuminate the track so that the locomotive engineer can identify moving or stationary objects or conditions at a distance of   244 m  (800 ft)  in front and ahead of the locomotive.  The reduced luminous intensity  (60 000 cd)  and distance requirements  (91.5 m  [300 ft])  for railroad yard headlight operation is required to reduce excessive glare for railroad employees.  [CandlePower Forum]

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 the technology 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 inversely proportional to the square of  d.  When looking at the corresponding light source on 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 first determine the total lumen rating inside the prototype.  Divide that by the above reduction factor and find a way to match that rating with whatever 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 in 3-pin packages similar to transistors.  Standard devices can supply up to  1.5 A  but Fairchild makes a low-power version in a small TO92 package (the LM317LZ) which can deliver up to  100 mA.

Mouser sells the LM317LZ for  51¢ a piece,  $2.98/10,  $14.10/100  or  $94/1000.  Bridge rectifiers are 41¢,  $3.69/10,  $33.90/100,  etc.

 Come back later, we're
 still working on this one...

Trois pattes  Short frame corridor coach, 13.58 m  (PLM express, 1906-1911 / SNCF modernized, 1953-1961)
LM317 is sold by  Mouser (Data sheets by  LinearTISTMicroelectronicsFairchild  and   ON Semiconductors).

(2014-03-16)   Layout Scenicing  &  Scenery Scales
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 originally entered 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 all because of the blatant scale difference when the trains are side-by-side.

However, the same layout could accomodate both HO and OO model trains at different times.  If that's the intention, then it's best to minimize the discrepancy between the trains and the scenery by choosing for the latter an intermediate scale  (sometimes dubbed HO/OO)  equal to 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 the background 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.

SubTerrain  video demo,  by  Woodland Scenics.
How to Make Backdrops for Model Trains  (using Instant Horizons prints over paintwork)  by  Mike Fifer.
Realistic Backgrounds for model railroads, by DQCI, Pittsburgh, PA  (1998).

(2014-04-16)   Mirrors and Shadows
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 a relatively nearby wall while preserving the illusion of true perspective.

That illusion of perspective, however, is immediately and utterly desroyed if 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 modelers and most of them are not even bothered by it on the final layout wherever it happens.  Neither are the spectators, because they 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 be completely destroyed by such shadows which are then seen for 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 simulate a 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 of terrain 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 accomodate lighting fixtures for the layout and hide the "end" of its fake sky  (a bluish curved surface starting vertically at track level and ending somewhat horizontally above that shelf, hidden from the eyes of little children at 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 part of 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 of the offending scenery element).  Such a technique is so unexpected by the brain of 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 midrange is through the use of mirrors.  We have all seen how small restaurants may appear much larger by having the upper part of at least one of their walls mirrored up to the ceiling.  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 can be 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 mirror or be hidden from it by scenery elements.  If at all possible, arrange things so that an object and its image are never seen together  (especially for trains and other moving objects).

For example, you may install a sunk track next to the mirror which is never seen directly but whose reflection in the mirror is partially 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 them at nearly  45°  from the main wall.  This can give the illusion of something beyond that 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 for the "subway" stairways of platforms  (when actual holes are ruled out).  One example is the  Butterfly Station Platform Shelters in the Walthers Cornerstone Series  (HO-scale, 933-3175 are sold separately from the matching 933-3094 Union Station).  The roof over the platform will typically prevents the spectator from looking directly into the stairwell and discovering the trick  (a first-surface mirror perpendicular to the stairs),  The illusion only works if the slope of the stairs is exactly 45° with identical vertical and horizontal surfaces  (which is the case in the aforementioned kit, probably to prevent the assembly mistakes that a more realistic asymmetrical design would allow).  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)   Coupling
Knuckle couplers.  Loop and hook.

Z-couplers don't hook up on corners.

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

 Come back later, we're
 still working on this one...

Kadee "The Coupler People".  Magne-matic® couplers.
Knuckle-coupler reviews  by  Dan Wexler  (Cupola, Winter 1999).
Bachmann video instructions :   The basics   |   How to use EZ-mate couplers   |   Maintenance

(2014-04-07)   Loading gauge and "six-foot way".
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.

 Come back later, we're
 still working on this one...

Structure gauge   |   Loading gauge   |   Berne gauge (1912)  =  Gabarit Passe-Partout International (PPI)

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

Various manufacturers of sectional track sell elements of curved track which are pecified to cover a fraction of a full circle  (usually expresses 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).

Note, however, that manufacturers occasionally advertise the footprint of circles made with their curved elements  (this is especially so in the specifications of starter set "ovals" with or without straight elements).  In such cases, what's given is the outer diameter of the circular track, which is equal to twice the central radius of curvature plus one track width  (including crossties and roadbed, if applicable).  For example, starter sets using Bachmann EZ-track curves with an  18''  central radius of curvature have an advertised diameters of  38''  (since EZ-track is manufactured to a width of 48.9 mm,  which is nearly  2'' ).

Central track radius of a full circle  (in mm)  for various sectional systems :
Manufacturers R1R2R3R4R5R6R9
 Fleischmann:  36° or 18°  356.5420.0483.5547.0
Roco:  30° or 15°  358.0419.6481.2542.8604.4826.4
Bachmann E-Z:  30°, 22.5° or 18° 355.6393.7457.2 558.8660.4711.2
Peco 371.5438.2504.8571.5
Hornby, Peco, Jouef: 45° or 22.5° 371.5457.2504.8571.5
Atlas: 30° or 22.5° 381.0438.2558.8609.6

Bachmann's EZ track curvatures
Radius / in 15''18''22''26''28''33¼''35½''
Radius / mm 381.0457.2558.8660.4711.2844.55901.7

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-center spacing between parallel tracks.  Half a dozen curvatures are commercially available in that system:

Kato's Unitrack curvatures
Radius / mm R430R490R550R610R670R730

The standard Unitrack siding  (featuring parallel track 60  apart, center-to-center)  entails a #6 turnout  with two compensator elements:  An R867-10  corrector curve and an  S149  (149 mm straight section).  The straight part of the #6 turnout is equivalent to two S174 The combined length of this assembly is

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(2014-03-17)   Double Track Spacing
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 called the  four-foot way  and the space separating the outer rails of 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 useful in sorting out the function of each rail in a busy yard.

In modern times, the quantity of interest is the center-to-center distance between 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 accomodate OO 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 a layout meant to accomodate HO and OO models.

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

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The Anatomy of Railway Vehicle Running Gear  by  Anna Orlova and Yuri Boronenko.
Double-track spacing  discussion on the Scalefour Forum  (P4 modeling).
Wikipedia :   Double track

(2014-03-30)   The  frog number  is the cotangent of the  frog angle.
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)  depends on 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.

NTangentUS speedRussian speed
#151/1530 mph48.3 km/h  
#201/2045 mph72.4 km/h  

 Come back later, we're
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A few problems with modular track systems :

The lengths of the straight sections in the #5 and #6 turnouts of Bachmann's EZ-track system are respectively  11½''  and  15½''.  Both are packaged with a small  2¼''  additional piece of straight 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 with regular pieces.  However, the underside of short pieces feature two slanted groves on the side meant to meant with the turnout.  You need two such pieces to use the turnout  (one ot them has to be purchased separately).  Soften the roadbed by bending back and forth two opposite groves on short pieces, then fold the roadbed inward  (you could cut it or break it bit you don't have to).  So modified, the pieces can mate with the two tracks at the heel 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 pieces from the EZ-track system  (4½'' and 2¼'' pieces are sold in packs of four, and an assorted pack of 10 pieces is sold as #44592 which contains 5 sizes:  ¾'', 1'', 1¼'', 1½'' and 2'').

Numbering straight and curved turnouts,  courtesy of Fast Tracks  (NMRA-compliant hand-laid tracks).
RP-12.3 turnout dimensions  (HO-scale NMRA recommended practices, Feb. 1961)
RP-12.7 turnout dimensions  (N-scale   NMRA recommended practices, Dec. 1979)
Frogs and switches  from the Catskill Archive.
Video :   An Introduction to Switches & Crossings  by  Network Rail  (engineering education, 12 of 15).

(2014-03-21)   Systems of Track Sections
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 the same length.  Turnout components are indispensable which allow a choice between a straight path and a curved one  (in a left turnout, the curved path is to the left of the straight one; it's the opposite in a  right turnout ).

For compactness and flexibility, the straight and curved sections in standard turnouts 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.

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Geometry of layouts using Hornby track elements   |   Peco HO/OO track

(2014-04-01)   Direct Current   (DC)
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 recent DCC protocol, this allows the control of only one locomotive per block, which can be 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)   Digital Command Control   (DCC) 
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.

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Specialized DCC makers :   North Coast Engineering  (NCE)
DC Loco on DCC  by  Mark Gurries
Wikipedia :   Digital Command Control (DCC)         DCC Wiki :   Digital Command Control (DCC)
Videos :   DC to DCC 101  by Eric G. Hall.
Opening the Digital Passenger Set by Bachmann  [ 1 | 2 ]  by  InterCity82 by Intercity82.

(2014-03-29)   Mobile digital sound decoders  (DSD)

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(2014-03-30)   Blocks and auto-reversing

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 still working on this one...

(2014-03-29)   Block Detection and Transponding
Locating DCC equipment by monitoring changes in current.

In a track layout divided into electrically isolated blocks, the current supplied to each block can 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 block that 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 least some 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 wheelset with a resistor of no more than 15 k  (to draw a current on the order of  1 mA  or more).  This is done with either a small surface-mount resistor or some resistive varnish  (containing tiny particles of graphite which come together and form a stable resistor as the varnish dries).

15 k  resistor wheels (detectable wheelsets) by  Logic Rail Technologies
Graphitage, vernis résistif, peinture graphitée (French)   |   Widerstandslack (German)
Graphit 33   |   TRIX 66882   |   Uhlenbrock 40410

(2014-05-31)   Controller Area Network
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 for registered 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 for Ethernet over twisted pair, which has replaced the thick and thin 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 evolution of Ethernet  (at times Ethernet innovations were advertised as working with existing cables, possibly by using more pairs).

An oversimplified history of Ethernet cables  (4 twisted pairs, baseband communications)
CategorySinceStandardEarliest usage
Cat31986IEEE 802.3e StarLAN, 1BASE5 (1 Mbps).
Cat51995EIA/TIA 10BASE-T (10 Mbps, twisted pair).
Cat62006IEEE 802.3an2006 10GBASE-T, 10 Gbps (100 m)
Cat6a2009TIA 10GBASE-T, 10 Gbps (100 m) 500 MHz
Cat7 Open

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

 Cat-5 TIA/EIA T568-B   Pictured at left is the TIA/EIA T568-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).
The electrically equivalent T568-A cables use conventions prevalent in the telephone industry, with pin assignments of the orange and green pairs swapped compared to the above.  Yet, the orange pair is still called #2 and the green pair is still called #3.  The surrounding of the center pair by another pair is inherited from traditional 2-line telephone RJ14 telephone jacks (6P4C) compatible with single-line RJ11 telephone jacks (6P2C).  The RJ25 three-line jack (6P6C) are mechanically and electrically compatible with RJ11 and RJ14 but do not obey the same logic as RJ45 or larger jacks, (the third pair is formed by the two outer conductors and has no equivalent in RJ45).

NMRAnet Physical Layer  (RJ45 connector and Cat-3 or Cat-5 cable)
PinT568-B ColorPairNameUsage
1Orange/white# 2CAN_H
2Orange# 2CAN_L
3Green/white# 3CAN_GNDConnected to 6 and/or 7, as needed
4Blue# 1 Reserved pair
(must withstand 100VAC)
5Blue/white# 1 
6Green# 3CAN_SHIELDConnected to 3 and/or 7, as needed
7Brown/white# 4PWR_NEG7.5 VDC to 15 VDC, 500 mA Max
(must withstand 27 VAC)
8Brown# 4PWR_POS

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.

OpenLCB   |   NMRAnet   |   Railstars IO Boards   |   TCH Technology (product guide)
NMRAnet Physical Layer  (NMRAnet / S-9.7 Standard Bus, adopted Aug. 2, 2012)
OpenLCB/NMRAnet Developer and Early Adopter Kit  (2012)
Origins of Ethernet   |   Ethernet physical layer   |   Power over Ethernet  (PoE)
Born in 1924 as the Radio Manufacturers Association (RMA) the Electronic Industries Alliance (EIA) ceased operations on February 28, 2011 to transfer its responsibilies to several independent sectorial organizations, including the Telecommunications Industry Association (TIA) recognized by ANSI and international organizations:  ITU, ISO, IEC.

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

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 still working on this one...

Videos reviews:  Bachmann 31-255DC:  Midland Pullman, blue livery.
Bachmann 51810  Alco 2-6-0 Mogul, Union Pacific #39 (HO scale, DCC Sound Value).
Hornby R3100  Class A3 (103) "Flying Scotsman" (OO scale, black livery).
Hornby R2991XS  Class A4 (60018) "Sparrow Hawk" (OO scale, garter blue livery, DCC sound).
Jouef TGV 150  574.8 km/h world record in 2007  (HO scale, garter blue livery).
Jouef has made two different sets based one the record-breaking train, both are discontinued:  One is a DC starter set with tracks, transformer and throttle  (ref. HJ1013).  The collector's edition (ref. HJ2058)  includes only a DCC-ready locomotive, three cars and a non-powered locomotive  (with fake pantograph).

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

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

Exreme Railways, by Chris Tarrant :

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 still working on this one...

Trois pattes  Short frame corridor coach, 13.58 m  (PLM express, 1906-1911 / SNCF modernized, 1953-1961)

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

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 still working on this one...

Trois pattes  Short frame corridor coach, 13.58 m  (PLM express, 1906-1911 / SNCF modernized, 1953-1961)

visits since May 6, 2014
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