Gradients and general Track Laying

[Acorncomputer]

Hi Longbow

Perhaps I struck lucky with Kent. I did place the route markers quite close, and as you say, the land gently undulates in that area so perhaps not a good example.

I'd also endorse the comments above about establishing benchmark track heights at points on the route, and adjusting gradients to suit. I do this by putting my start height and gradient profile into a spreadsheet, calculating elevations at key points along the route, and comparing these to my spot height benchmarks and to the DEM terrain at these points. If things don't match I can then tweak gradients and/or distances in the spreadsheet to suit.

As I am still tackling many aspects of route building for the first time I will try this out and see what I can learn. With such a short route I can afford the time to at least try some of the techniques which may be useful or necessary later on in a more substantial route.

[anamorph]

As I am still tackling many aspects of route building for the first time I will try this out and see what I can learn. With such a short route I can afford the time to at least try some of the techniques which may be useful or necessary later on in a more substantial route.

When placing markers, I tend to use the following abbreviations:
CS = Cutting start
CE = do end
EE = Embankment start....etc
ELEVxxx = target spot height

If going up, or down gradient it helps to see visually where you need to be, and you can adjust gradient to get what should exist in terms of cuttitngs etc (within reason).

While it's tedious sometimes, it is well worth spending time getting your marker files in 'first time' - you can't really have too many - especially on curvy bits of route.

[Acorncomputer]

Hi All

Thanks for your ideas.

I originally marked out the track without the gradient information but now that I have this, I am going to try a little experiment. I will prepare a new set of markers placed at gradient changes (there are only 15), place these in the bare route, set the first piece of track at the right height, location and gradient, bring down the terrain below the whole track and then lay the track in mid-air using only the gradients and distances from the track start to lay the track. If I then bring the terrain up again and snap it to the track, the terrain should automatically create cuttings and embankments in the right places.

I do not have much expectation of this working as Longbow has already pointed out that the terrain is not that accurate in the first place, but I think it is worth a try, if only to eliminate it as a workable technique.

I will be starting a new thread on The Spa Valley Railway shortly and will blog my findings on there - for anybody that is interested.