This page last updated 5th January 2000  

A Discussion on an NZ120 Module Standard

NZ120 is the common name (within New Zealand Model Railway Guild circles) for a scale more accurately referred to as TTn3.5, that is 1:120 scale (or 1/10" to the foot) modelling of a 3'6" prototype (the gauge of all of New Zealand's rail lines).

NZ120 uses standard 9mm N scale track, wheelsets and locomotive mechanisms. The appeal of the scale is similar to that of N Scale: it is ideally suited to small layout areas, and to more fully recreating the glorious mountain scenery of New Zealand than is possible in the larger scales.

Most of the NZ120 devotees are of limited means, and most do not yet own their own layout room (with or without house attached). Hence there is some logic in building modules rather than fixed layouts.

Why not use an existing Modular Standard?

N-Trak

I've been involved previously with N-Trak, which has worked very well as a concept in the USA and for US Prototype clubs here in Australia, but which is not suited to the modelling of the NZR prototype; the 3 track mainline concept doesn't fit with a prototype that rarely has even double mainline track, and the totally flat topology exists in few places in NZ.

Also the concept of N-Trak has met with difficulties when local groups make "minor" changes to the standards to fit in with local materials. For example, in Australia they have two standards for length; (i) multiples of 2 imperial feet (ii) multiples of 600mm.

N-Trak meetings are great when the right number of modules turn up, as usually the group plans to have a rectangular closed loop. This only works when there are lots of modules and you can match the length of the sides. I.e. even assuming that the four 90 degree corner modules are the same size, it doesnt work if three people bring a four foot module and the fourth brings a six foot module.

I like the idea of the N-trak "Mountain Track", but have never personally seen it implemented. Northern Virginia NTrak have some track plans which use the mountain track.

OneTrak

OneTrak is a modification on the N-Trak scheme, reducing the number of mainlines to one, and providing for more flexible module shapes and sizes.

Bend-Trak

We got quite excited when we first found this group. They have made a number of changes to the N-Trak concept that fitted our ideas.

We particularly like the concepts of

• Freedom in the length component
• The move away from forced rectangular baseboard
• A built in 'return track", i.e. no need to build a 'wagon circle'
• Once the organiser has provided the two balloon loops a meet can proceed with any number of modules

However, with four visible tracks on every module (or at least two if you put in the centre divider), there are still more tracks than we'd like to have as a minimum.

FreeMo

FreeMo have taken the concept of Freedom of size to pretty much its logical conclusion. With one mainline this is starting to look like it has possibilities! It does however lack the best feature of BendTrack, being the balloon loops to allow more flexible setup of modules.

Use an Existing Standard? - Summary

Of these four, none of them quite meet our requirements, but certainly good food for thought.

Our Proposed NZ120 Module Standard

From looking at the existing standards, and a fair bit of discussion we have come up with the following wish list:

• Single mainline as the standard
• Single sided viewing - the NZ scenery is generally hilly, so it makes more sense to us to have a backdrop to allow terrain to proceed above the track height
• Freedom in the length component
• No need to have a rectangular baseboard (although we expect that for practical reasons most modules will end up either rectangular or creating a 45 or 90 degree corner).
• A built in "return track", i.e. no need to build a "wagon circle".
• Once the organiser has provided the two balloon loops a meet can proceed with any number of modules.
• Optional "Mountain Track" to allow secondary operation within a smaller group of modules.

Once we started to think about terrain, we quickly found why N-Trak has a flat profile! We do want to have hills rising behind the track, but this requires that the mating ends not only are the same width, but that they have a common end profile. We think we'll solve this by making a prototype template and requiring that this gets used when making up the modules.

So what have we come up with?

• Module End Dimension of 600mm deep - i.e. nominal 2' - (given that NZ wood is now metricated)
• No restriction on length of module, or shape of module, as long as the ends are the correct depth.
• Single Mainline track (9mm guage of course) 150mm from front of module to front rail of track, and perpendicular to Module End for at least the outermost 75mm.
• Modules to be connected with Atlas brand set track 128mm long (i.e. track set 64mm in from each edge).
• Fixed backscene 525mm from front of module (still under discussion).
• Return track at 575mm from front of module to front rail (i.e. behind backscene). Return track able to be expanded into a storage/switching yard on any module or group of module(s) by adding additional depth behind backscene. Similarly freedom to add Wye configuration to allow yard to be setup in middle of 'wagon circle' layout if desired.
• DCC operation as standard
• Obviously the mainline can branch within a module or modules, but must return to the single line position at the mating ends
• Mountain Track defined as 50mm higher than mainline track, and 550mm from front of module. This places the Mountain track behind the backscene. The intention is that should a modeller not want to scenic the mountain track they can leave it hidden for the width of the module. If a modeller wants to use it then they turn the mountain track out through the backscene and across their module(s).
• As an alternative we thought about having the Mountain Track further forward (say only 500mm from the front. This would place it in the middle of the end profiles. If a modeller wanted to use it they would have to build a tunnel portal or cut at the ends. Those who didnt would either continue the terrain to the profile of the ends (thus having the mountain track in a full length tunnel) or turn the track out through the backscene and bring it back out before the other end of the module.

So if you want further information or have input, please email Andrew Wells at nz120@xtra.co.nz