IBLS Track Standard

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Correct way to measure gauge
ScaleRatioStandard GaugeNotes
001:6716.5 mm
0.650 in
Hornby produced.Generally regarded as the smallest scale for live steam.
O1:4532 mm
1.260 in
Popularly used for the small scale live steam.
No. 11:3245 mm
1.772 in
Popularly used for the small scale live steam. Corresponds to NEM 1 or NMRA #I.
No. 3
1:22.663.5 mm
2 1⁄2 in
The smallest scale able to pull real passengers. Was one of the first popular live steam gauges, developed in England in the early 1900s. In terms of model railway operation, "Gauge '3' " is the largest (standard gauge) scenic railway modelling scale, using a scale of 13.5mm to the foot. The Gauge '3' Society represents this aspect of 2½" gauge railway modelling with both electric and live steam operation. Gauge '3' corresponds to NEM II scale, also known as 'Spur II' in Germany.

The National 2.5" Association continues to support live steam passenger hauling in 2.5" gauge using MES Tracks. They use a 'scale' appropriate to the original prototype modelling both standard and narrow gauge locomotives to run on 2.5" track.

3/4"1:163 1⁄2 in
89 mm
A worldwide garden railroad scale. Corresponds to NEM III and NMRA 3/4".
1"1:124 3⁄4 in
121 mm
North America specific scale corresponding to NMRA 1" scale. 1:12 is one of the most popular backyard railway scales.
1"1:115 in
127 mm
Used outside North America. Corresponds to NEM V. One of the most popular garden railway scales.
1.5"1:87 1⁄4 in
184 mm
Used in North-Eastern USA, Canada and the world outside North America. Corresponds to NEM VII.
1.5"1:87 1⁄2 in
190.5 mm
Used in North America outside of New England and Eastern Canada.
1.6"1:7.57 1⁄2 in
190.5 mm
1.6in=1ft. Used in the USA, often finer-scale. Uses 7.5in gauge.

Rail Gap

Thermal expansion can cause track misalignment, typically referred to as "sun kink". Track must be laid with gaps between adjoining rails to reduce the likelihood of sun kinks.

The table below provides recommended gaps for the ambient temperature when the track is laid. Gaps are indicated in fractions of an inch and temperature is in Fahrenheit. Note that the scale of the rail has no bearing on the size of the gap required.

IBLS Rail Gap Standard
Rail Type Rail Length (inches) 0°F 20°F 40°F 60°F 80°F 100°F 120°F 140°F
Aluminum (6063-T5) 120 1/4 3/16 5/32 1/8 3/32 1/16 1/32 no gap
Aluminum (6061-T5) 120 1/4 1/5 1/6 1/8 1/10 1/16 1/32 no gap
Steel 120 1/8 1/10 1/13 1/16 1/20 1/32 1/64 no gap
Aluminum (6063-T5) 240 2/5 3/8 5/16 1/4 3/16 1/8 1/16 no gap
Aluminum (6061-T5) 240 1/2 5/13 1/3 1/4 1/5 1/8 1/16 no gap
Steel 240 1/4 1/5 1/6 1/8 1/10 1/16 1/32 no gap


From http://www.trainorders.com/discussion/read.php?3,2249399

Date: 08/08/10 08:05

Many thanks to Mike ONeill of Parker, CO for providing some general info on Live Steam track gauges. In the United States and Canada, no one could ever come together and "standardize" on what certain scale gauges should really be, which was unfortunate. Some examples: The standard gauges as adopted by the NMRA years ago for the small live steam railroads are--- 2 1/2 inch (1/2" scale); 3 1/2 inch (3/4" scale), and 4 3/4 inch (1" scale)... In the UK and Canada, 5 inch gauge represents 1" scale...

In the Western U.S. the gauge for 1 1/2" scale is 7 1/2 inch gauge. In the Eastern U.S. the gauge for this same scale is 7 1/4 inches. The same in Canada. Neither gauge is truly correct for the scale involved. For the absolute "purist", the gauge for 1 1/2 inch scale works out to 7 1/16 inches.

This is really a shame because Live Steamers in different parts of the country are "restricted" on whose tracks they can visit and run on. Many years ago, one of the older GGLS members in Oakland, CA built an absolute stunning model of a STEAM locomotive as well as a Steeple-cab locomotive that drew power from either Overhead wire or outside 3rd rail (a 'la SN) and a large beautifully constructed wood caboose. His name was Louis Lawrence and he resided in West Oakland. However. he could ONLY operate his beautiful creations in his own backyard. Why ?? Because for some strange reason he built them with a track gauge of 6 3/8 inches.

The track gauge on Erich Thomsen's "Redwood Valley Railroad" was originally 12 inches before he enlarged it to the current 15 inches.

Anyway, even with early-day intervention by some of the IBLS secretaries, the gauge drama still lingers on. If you are a Live Steam hobbyist, you RUN where you can.

North American Region
International Brotherhood of Live Steamers

Model Rail Types

This is a survey of historic and existing rail form factors and their suppliers. If you have data to contribute to this survey please contact Daris Nevil.

  • Buddy-L Rail
    • For 3/4" scale - 5/8" high - steel, rolled by Bethlehem Steel Co
  • Cannonball Rail
    • For 1-1/2" scale - "Standard" - 1" high, 7/16" wide head, 1/8" wide web, 3/4" wide foot, length 10', aluminum
    • For 1-1/2" scale - "West Coast" - 1" high, 1/2" wide head, 15/16" wide foot, length 10', aluminum
Cannonball Ltd "Standard" aluminum rail profile, from their 2004 catalog.
Cannonball Ltd "West Coast" aluminum rail profile, from their 2004 catalog.
  • Culp Rail
    • Peter Nuskey, a machinist in Pennsylvania, has been offering Culp Rail (a 1/8 scale aluminum model of Pennsylvania Railroad’s 115lb steel rail) for over 40 years, as of 2012.
    • 1-1/2″ scale rail 0.825″ high – 10′ lengths – 6061T6 Aluminum
    • 3/4″ scal rail 0.625″ high – 10′ lengths
    • LGB rail 0.335″ high – 10′ lengths
  • L S Rail
    • Aluminum 6063-T5, 1.5 Scale LS Rail, 10′ lengths
  • Real Trains
    • For 1" scale - 0.500" high, 0.234" wide head, 0.457" wide foot - 6061T6 Aluminum
    • For 1-1/2" scale - 0.891" high, 0.369" wide head, 0.750" wide foot - 6061T6 Aluminum
    • For 3" scale - 1.500" high, 0.600" wide head, 1.200" wide foot - 6061T6 Aluminum
  • RMI Railworks
    • For 1-1/2" scale - 1" high - 6061T6 aluminum and steel
  • West Coast
    • 1" high, 1/2" wide head, 15/16" wide foot
  • George Pruitt's "Groovy Rail"
    • Does not require fasteners

Rail Profiles

ASCE Rail Profile for 10020 rail

Supplementary Information



From Large-scale Model Railroading, page 52:

On curves, there is more resistance or drag to the train. For this reason, grades should be reduced when a curve is involed. Using prototype figures as a guideline, we find that our grades should be reduced as follows:
  • 1/2 percent on a 125 foot radius
  • 3/4 percent on a 75 foot radius
  • 1 percent on a 60 foot radius
  • 1-1/4 percent on a 50 foot radius
  • 1-1/2 percent on a 40 foot radius

Elevated Track

See Elevated Track.


  • "Mini-Rail News - Track Standards", Lewis Soibelman, Live Steam Magazine, Mar 1991