The Random Thoughts of a Geek heading for Banbury
The Random Thoughts of a Geek heading for Banbury

Basic Duplo Track Stuff

Track Infrastructure

The image1)) shows the names of the track infrastructure,

Four foot

The space between the running rails measured from the edge of the baseplates underneath the rails (rail chairs) is known as the ‘Four Foot’ despite not being four foot, on Standard Gauge2 it is 1435 mm (4′ 8 1⁄2″ or 56.5 inches). Wider is generally known as ‘broad gauge’, and narrower is ‘narrow gauge’3.

On Duplo track this is about 31.9 mm

Six Foot

The space between adjacent running lines of a two track railway. Where there are more than two tracks, the distance between pairs of lines is usually greater than six feet.

Ten Foot

10ft is the central space between adjacent pairs of running lines on a four track railway. this may actually be less than the six foot.


The area either side of the railway immediately off the ballast shoulder. This usually provides a safe area for authorised workers to stand when trains approach.

Duplo track

Loading Gauge

To be compliant with D1 gauge:

  • The load (which may be anything) when placed on a wagon must be within the static gauge line for the D1 gauge.
  • When the vehicle negotiates curves, the load must remain within the adjusted (for overthrow) gauge line for the gauge.
  • The wagon itself must remain within the gauge lines (bogies and bodies are considered separately as bogies have less dynamic movement than bodies).
  • The bogies must have the same characteristics as those defined for the gauge.

Based on The V/S SIC Guide to British gauging practice.

Duplo Rolling stock

The image to the above 4 shows the main parts of a freight wagon, including labelling the Headstock, and the Solebars.

The Cant rail5 is not shown on this diagram6.

Track and Plain rolling stock Load Gauge D1 Load Gauge D2
4s x 1.5d (64 x 28.8mm) from the top of the flange way (to top of solebar).

Maximum rolling-stock wheel base should be limited to 8s (128 mm) long, Lego rolling stock is available in flat trucks of 4×2, 6×2 8×2 and 8×4 studs.

From top of solebar 4s x 3d (64 x 57.6mm) to cant rail, then 2s x 1/2d (32 x 9.6mm) centred above cant rail.

D1 shall not project beyond the face of the headstock, as this clearance allows for use on all normal grey and black Duplo pway

From top of solebar 8s x 3d (128 x 57.6mm), with 6s x 4d (96 x 76.8mm)above.

D2 compliment rolling stock shall be constructed should be designed to fit in a 8s x by 8s footprint, however at 8s wide may have issues with parallel tracks.

== Schnabel cars ==

[[wp>Jacobs Bogie]]

=== PWay and structure gauge ===

The structure gauge, also called the minimum clearance outline, is the minimum height and width of tunnels and bridges as well as the minimum height and width of the doors that allow a rail siding access into a warehouse. In addition, the term may apply to the minimum distance to railway platforms (passenger or freight), buildings, electrical equipment boxes, railway signal equipment, third rails or to supports for overhead lines from the track. The width of a narrow cut can also affect the maximum loading gauge.

The difference between the structure gauge and the loading gauge is called the “clearance”. The amount of clearance between the loading gauge and the structure gauge depends on the speed of the train, due to the train wobbling, so a train may be able to get past a restricted clearance by travelling at slow speed.

Wikipedia article on Structure gauge

This is not necessarily explicitly about MOCs, however talks about basic concepts that I find useful.

It is useful to know the dimensions of a LEGO brick, and the multiples, these links relate to the size, and give a helpful background:
* [[|Basics]]
* [[|Measurments]]
* [[]]

{{tag>Lego Duplo MOC}}

Related Articles

  1. Image from the PTS booklet
  2. Also known as Stephenson gauge, International gauge, UIC gauge, uniform gauge, normal gauge and European gauge in the EU and Russia
  3. Wikipedia has a good Standard gauge railway article
  4. Image from Goods & Not So Goods – An overview of railway freight operations for modellers (here).
  5. Cant Rail – the part of a vehicle or traction unit at which the profile between the body-side and roof changes Railway Lexicon
  6. The Cant Rail can be seen on the diagram available here