TUNNELS

Sometimes
that light at the end of the tunnel
is a Z Scale train.

 

 
 
Model trains and tunnels go together well, and they have a long history together, too. For many layouts, a tunnel was (and still is) a major scenic feature and hence attraction; its scenic and dramatic impact is easily understood - a train vanishes into or appears out of nothingness.
 
But for this to really work, a tunnel needs a reason to be there. The one-piece scenery item which basically consists of a very short hill with two portals, plopped down on an otherwise flat layout, is a common feature of the toy train oval layout and illustrates the vexing effect a lack of context produces - it almost appears that the railway was deliberately heading to the one and only obstacle in its way just to build a tunnel (when in reality tunnels, like bridges, are expensive feats of engineering any railway company will avoid if at all possible).

A tunnel on a layout attempting at least a semblance of realism will therefore have two aspects: the tunnel portal itself, and its setting.

 

 
Tunnel portals (i.e. the structure lining the entry and exit to a tunnel) come in a plethora of different shapes and sizes, depending on era, location and type of tunnel bore. They also differ in terms of materials used, ranging from wood, cut stone, brick and concrete.

The selection of tunnel portals available in Z Scale is quite extensive, and depending on the prototype modelled there are a number of plastic injection, plaster, gypsum cement (hydrocal) and card models available. Personally, I have been using various cut stone and concrete portals from Z Train Things which are made from hydrocal.

 

 

 
 
  The castings feature quite some detail, the depth of which is brought out by an initial base paint in black. Followed by a gentle misting of gray (I simply use an acrylic spray can), the nooks and crannies which still retain their darker colour really "pop".

Additional subtle layers of slightly differing colours add even more relief detail to the portals.

 
Once the portals have that more or less weathered look, they need to be set in context on the layout.
 
    Generally speaking, tunnels are associated with hilly or even mountaineous terrain, and this is especially true for model railroad layouts. However, tunnels can also be found in abundance in urban contexts, where retaining walls will provide the setting more than steep slopes or granite rock faces.
 
 
Building up terrain on a layout can be done in many ways, but for Z Scale especially I have found using styrofoam to be a very workable approach. But whatever the technique, it is important to embed a tunnel portal rather than just stick it on the end of some form of evelation and/or barrier to the continuation of tracks.
 
    At the same time there is the problem that although model tunnels are mostly just mock-ups, the entry area to the tunnel should at least display some form of walls hinting at the tunnel bore.

Both aspects can be adressed in one go by using a piece of styrofoam which is about one inch /2.5 cm deep. Cutting out a "bore" a little larger than the actual portal profile provides both a base and a few scale yards of tunnel entrance.

 
This is best painted black, alluding to the darkness ahead once a train enters that tunnel.

Rather than having a more or less sqaure base onto which the portal can then be glued and worked into the surrounding scenery, this can also be shaped in advance.

Measuring up everything with diligence pays dividends here, as the portal base can then either simply be slid into a pre-exiting basic styrofoam scenery or worked up from there more easily than if the portal is a later step in creating the scenery.

Most tunnels on layouts are, for obvious reasons, nowhere near as long as they are in the real thing - not the least because, as scenically and operationally effective as a tunnel is, we actually want to see our trains.

 

 
  However, even short tunnels require some form of hidden access in the case of derailments or stalled equipment. Factoring this into the early planning stage is much easier than having to do this as an afterthought.

And yes, having no access at all other than through the small Z Scale tunnel portals will trigger Murphy's law and provide for a potentially frustrating spot of trouble.

 
 
On the real railways of the world, tunnels built early on in the development of a rail transportation system may over time become obstacles as their loading gauge can not accomodate taller and broader rolling stock. As the pioneer in the field, English railways are especially plagued by this, even leading to more modern locomotives built to fit the smaller tunnel profiles (e.g. the Class 33 "Slim Jim" versions for the Hastings line in South-East England). The more common approach is to increase tunnel clearances, either by widening the bore or/and lowering the trackbed (both of which methods have been employed e.g. by Norfolk Southern to allow double stack container trains through the many tunnels in Appalachia).
 
    On a layout, things work the other way around: first decide on the rolling stock you want to run, then choose the tunnel portals.

Checking clearances is essential if the trains supposed to run on the layout are also supposed to clear the tunnel entrances (and, obviously, what lies beyond).

 
It is therefore important to identify the rolling stock with the largest loading gauge profile in order to check clearances.
 
  In this case, a double stack container car is actually higher than an autorack, although the latter has a more pronounced tendency to "lean", so it's good to check with both. That way, the tunnel clearance should be fine for all and any rolling stock.

Most Z Scale models of tunnel portals were designed either prior to the advent of traclk with an integrated roadbed (such as Rokuhan and Micro-Track) or they simply do not take the maximum loading gauge formula (double stack containers plus roadbed) into account. It can therefore sometimes be necessary to raise the portal base; the resulting gap can easily be covered with scenic material.

 
 

 
 
 


(c) 2018-2019

All images unless noted are (c) Adrian Wymann

     

page created 30 December 2018
last updated 13 March 2020