The layouts on this page use both standard LEGO and TrixBrix tracks.

All track layouts were created with Bluebrick and the TrixBrix track library for Bluebrick.

The Bluebrick files can be downloaded here.

Switch Generations

The original LEGO switches have developed over many decades. With the introduction of the 9V system, the standard track spacing changed from 0 to 8 studs. Parallel tracks without space in between could be realized only with difficulties from this moment. In 2020, TrixBrix introduced the “Zero Gap Switch” and made track without gaps possible again.

The R40 Railyard System

The R40 railyard system uses a special railyard switch. The base of that R40 railyard switch has the ground throw on the outer side, and it has a slightly shorter straight track in their split track segment than a standard switch. The advantage is, that no additional special adapters are needed to build R40 railyards.
The R40 railyard system was designed by Mattzobricks and then adopted by Trixbrix.

The R104 Railyard System

The R104 railyard system uses the standard R104 switch for both entry and railyard switches. The switch base of the railyard switches just need to have the ground throw on the outer side. The R104 railyard layouts need additional special RC1 and RC2 adapters to be able to come out with the parallel tracks at the standard spacing of 8 studs and on the same length.

Railyard R40 vs. Standard Switches

A parallel track that is initiated with a railyard switch directly from an R40 curve is 3 standard tracks longer than a parallel track that is built with standard switches. As an additional advantage, the trains do not derail so easily when entering the track via the railyard switch, because the abrupt curve change within the standard switch is omitted.

Railyard R40 vs. R104

The railyard system in the R40 and R104 system are similar, but they have differences in detail. In the R40 system, a special railyard switches must be used, but no additional special adapters are required. In the R104 system, the standard R104 switch can be used for all branch-offs, but two special adapters are needed. R104 railyard systems are one standard length (16 studs) longer than the corresponding R40 railyard system.


There is a variety of possibilities to create loops. The track plan shows six different options.

R104 Ballast Curves

The R104 Ballast Curve (R104BC) is about 0,2 studs longer than the standard R104 curve. The R104BC is needed to build a precise counter curve for parallel tracks that fork off from a R104 switch.

Compact station with 4 tracks and partial R104 switch fields

A perfect compact station with 4 tracks.

Station with 4 tracks and complete R104 switch fields

As above, but now every track can be reached from each main line track.

Station with 4 tracks and double slip crossover

Using R104 double slip crossover switch combinations at the end of the station tracks saves a lot of space and allows that every arriving track can be switched to any station track.

Station with 4 tracks and diverging double slip crossover

The double crossover with R104 double slip crossover adapters can be used to open diverging tracks at the end of the station.

Station with 4 tracks, R104 switch fields and diverging tracks

A compact 4-track station with diverging main line tracks in the end.

Switched double track curve section R104/R120

As curved switches with radius R104 are not available yet (as of May 2020), I had to be creative and invented this perfect switched curve section. Both tracks are perfectly parallel, have the standard spacing of 8 studs and end parallel on the main grid.

Switched double track curve section R104/R120 with 3 exits

An extension of the version with 2 exits above.

Switched triple track curve section R104/R120/R136

An extension of the double track versions above. The outer curves are R120 curved tracks; with the straight half tracks and the slight offset in the beginning and end they form a R136 radius quarter curve.

Diverging parallel tracks with R104 switches from 2-track main line

There are several ways of building diverging parallel tracks with R104 geometry. This example has the closest parallelity of the diverging tracks. It uses one 4-stud-adapter and one 1-stud-adapter to achieve perfectly parallel tracks with 8 studs difference after the curve quadrant.

Diverging parallel tracks with R104 switches from 3-track main line

The inner circle of this diverging track section is built with R88 curves, the outer one R104’s.

Diverging parallel tracks with R104 switches from 4-track main line

Again, we are using R88 and R104 curves for the diverging parallel track. In this example, the switch field also contains a star crossing, which might be useful in some situations.

R104 Diverging Tracks

R104 curves are great, because you can use them for both building parallel tracks, and diverging tracks with R104 radius. It should be noted that the bow section of the R104 switches are about 0,2 studs longer than 2 R104 curves. For this reason, the quadrant of a diverging track containing the switch is not a precise R104 quadrant, but is somewhat enlarged by the switch bow. To compensate, you can use R104BC as the second curve behind the switch.

R104 Switch Field with Star Crossing

The star crossing can be used to cross a track from two neighboring parallel tracks on the same location.

R104 Crossing 45° with Switch Field

The R104 crossing 45° is similar to the star crossing in its geometrics. It is used in R104 switch fields to build parallel tracks that have a distance of 32 instead of 16 studs, measured from middle of tracks. The application of this crossing will not be too frequent in practice, but there might be situations where the part may be handy.

Large Crossing with 4 R104 Triple Switches

Building a large R104 crossing is problematic and only possible with 8 pieces of the 1-stud straight track adapters. The adapters must be inserted in the four straight track sections, and between the second and third R104 curve between the switches. The reason is, that the bow section of a R104 switch is 0,2 studs longer than two R104 curves.

Large Crossing with 2 R104 Triple- and 2 Wye-Switches

The geometry of this variant is equals to the geometry of the large crossing with four R104 triple switches.

Large Crossing with 4 R104 Wye-Switches

In this scenario, the adapters are no longer required.

R104 Monster Switch Components

There is no doubt that the R104 monster crossover switch field is clearly an ingenious design. The key idea of the concept is to combine switches on limited space, so that they cross in their detached sections. Left, right and triple switches can be used. Additionally, the R104 (monster) crossover can be extended by a quadruple switch adapter that allows to integrate R104 double slip switches into the crossover combination.

Double Slip Crossover R104

Extended Double Slip Crossover R104 with six tracks

Double Slip Crossover Switch Field (XL)

Double Slip Crossover Switches in Monster Crossover R104

Parallel tracks with 4 studs distance and R104 switches

Sometimes it can be handy to build track geometries with 4 studs space only.

Parallel tracks with 4 studs distance and R40 switch

The picture shows a TrixBrix 4 Stud Gap Switch (top) and a 4 stud combination that was built with a standard R40 switch, also from TrixBrix (bottom).

4-track station with reduced track distance

4 stud spacing is especially useful when building compact stations or railyards, and can also be combined with standard 8 stud spacing to place platform between some tracks.

5-track station with reduced track distance

In this example, the spacing alternates between 4 and 8 stud spacing for accomodate for platforms in every second gap.

6 thoughts on “Geometry Corner

  1. hi,
    I would like to know how to make Paranel tracks with 4 studs distance on what swtich R40 or R104 and special size of track to make it 4 stud between gaps?


    1. Well, I have come up with a couple of solutions to build layouts with 4 studs track spacing – check the “Parallel tracks with 4 studs distance…” layouts on this page. Most of the examples are based on R104 switches. It is true that you can also do some magic with standard TrixBrix R40 switches. You need to attach a R32 counter curve followed by a R40 half curve just after the branching tracking, again followed by the following straight tracks: 4/16, R2, 1/16. That comes pretty close to a similar solution. Nevertheless, the home-brown solution has the disadvantage that the whole combination is 8 studs longer than the TrixBrix 4 Stud Gap Switch. I have added an example to the page just below the “Parallel tracks with 4 studs distance” example. Does that help?

    1. RC1 and RC2 are adapters that TrixBrix introduced to build railyard ladders with R104 switches. RC1 has a length is approximately 1.81 studs, RC2 is 1.37 studs long. See for supplier information.

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