The second tier

[Ray H]

I've seen a number of layout ideas that involve a second tier/level. I'm wondering how the upper level is supported given that the usual framework/support for a baseboard is quite deep and providing similar support to the upper level could potentially require lengths of gradients where the design becomes impracticable.

 

I can see that a small (rail carrying) bridge over a track probably doesn't need much more support than the thickness of the material on which the track is mounted (assuming that this is something a little thicker than paper!). What happens when the second tier for example accommodates a station and there are random tracks on the lower level? My hand is approximately 120mm across and a softwood framed baseboard is usually around 25mm to 30mm deep at a mimimum. It would require around a 5m run with a 1 in 30 gradient to climb up 150mm to a second level that allows for this.

[Trofimow]

It depends on the kind of layout you have in mind. What works for a large fixed layout probably won't work on a smaller portable one.

 

All sorts of tricks can be used to help reduce the problem.

 

My layout has 3 decks, with the climbing tracks between them at 1 in 80. The gradients run round the edge of the room which allows a run of about 12 metres between decks.

 

The main structural deck is the middle one, used for parallel storage loops. This is of old fashioned construction using 2x1 timber and chipboard.

The upper deck is of reduced structural depth by using 2x1 timber laid flat rather than vertically, braced by 1" square timber and topped with ply. This reduces the height differential to be covered by the trains between the two decks. In addition, the upper deck tracks are for a large part 1" below the surrounding scenery, which increases the between deck height over scenic areas without increasing the gradients and also allows longitudinal stiffening to go above the trackbed rather than below.

 

Also, the middle storage deck is not level, but continues to descend from the point of entry through the storage to the return loop, thus gaining more between deck clearance and improving access.

 

The lower deck is inside the supporting legs and the upper deck beams support beams are outside the legs, which also improves accessibility.

 

On one route where there was less than ideal linear distance available, I cheated by making the descending gradient 1 in 30, thus stealing distance from the descent to use on the climb out to meet the 1 in 80 requirement. If you do this and intend to run long trains, feedback control is highly desirable to prevent heavy trains running away on the downgrade.

 

From the centre deck, two tracks run round the room again to descend at 1 in 80 to the lower deck and provide 2 tracks of serial storage. The structure here is a narrow strip of ply 2 tracks wide with 1" square timber along the edges to provide the structural stiffness and at the same time contain any derailments. The structural depth is thus contained within the height of the train and the narrow width means vertical clearances can be minimal without restricting access.

 

In some places, use has been made of 2" aluminium angle and T section recovered from a suspended ceiling to edge ply for the gradients. This can be screwed direct to the wall or support legs and reduces the structural depth to little more than the thickness of the ply itself.

 

I'm away working at the moment, but will post some pics later in the week if anyone wants to see what I'm waffling on about.

 

Alan