As avid readers will know, the railway comes out of the undergarage at a height of 53cm above ground level. The aim is to descend to ground level for at least part of the layout, so trains will have to go down hill once they emerge into the garden.

But what goes down must come up, and to get back to the undergarage, they will have to climb the same slope. So one important thing to do was to check what slopes the locomotives I can have can manage to climb.

Peter helped me with the tests. The main load was the infamous tea flask (filled for this test with water, so weighing over one kilogram) which needs to be able to be delivered to anywhere on the line.

We had a plank of wood 255 cm long which we used to elevate the track to check what performance could be achieved.

The test was done first with the diesel locomotive, and then again with the steam locomotive hauling three coaches and the flask.

We used one centimeter thick tiles to increase the slope gradually.

It was a stress test, so we kept increasing the slope until the locomotives could no longer haul the load. Here are our results (sorry doesn’t format very well on a phone screen).

Rise (cm)	Slope as Ratio	Slope as %	Diesel Result	Steam Result
4	1 : 64	1.57	Success	Success
6	1 : 42.5	2.35	Success	Success
8	1 : 32	3.14	Success	Success
9	1 : 28	3.53	Fail	Success
10	1 : 25.5	3.92	Fail	Success
12	1 : 21.3	4.70	Fail*	Success
14	1 : 18.2	5.49	Fail*	Fail

*Not tested but assumed to fail.

The steam locomotive actually has two engines, one in the main body, and a second in the tender, so it is not surprising it performed better.

So what was our conclusion? Rather surprising, since I was assuming that we should not exceed 1 in 50, or maybe 1 in 40.

We concluded that we could construct the outside line with slopes of up to 1 in 32. This will allow both types of locomotive to haul the worst case loads. Most of the time the loads will be much less than this, so there will be plenty of performance available (or put it another way, operations will be possible even when the batteries in the locomotives are partially discharged).

So when will be reach ground level? Well, that depends not only on the initial drop to be covered, but also on the subsequent slope of the garden itself, which was estimated originally to be around 30 cm, without any good scientific evidence to support this.

I don’t have a surveyors theodolite to properly survey the garden. But we checked the wall which runs along the side of the garden, and using the big spirit level concluded that to all intents and purposes, the top of the wall is level.

So that became our zero, and everything else was measured relative to that.

I have an electronic tape measure which uses a laser beam to measure distance. Further use of the spirit level enabled us to find a point at the same height at the wall on the exit window from the undergarage.

So we determined that the exit level was -53 cm RTTTOTW (relative to the top of the wall) (surely a coincidence that this was exactly the same distance above the ground at the same point).

We then we able to check the level at the fence which splits to garden in two: -115 cm RTTTOTW, a drop of 62 cm from the undergarage exit level.

Judicious use of a pole (what’s a pole for??) [sorry, family in-joke] allowed us to calculate the height at other points of the garden.

We found that the grass next to the pond is at -152 cm RTTTOTW and the cherry tree is at -157 cm RTTTOTW (so another 42 cm lower than the fence!).

At 1:32 we will reach ground level when we get to the fence, but will need to continue going down to get to the pond and the tree (but along the ground essentially, since it is falling in parallel). Lots of civil engineering required! But feeling much happier since at least we know what we need to do.