A cause of some consternation on a couple of projects I started recently. When laying a double track section using seperate single splines I find that one spline seems to sink or sag lower in the terrain than the one next to it. This happens whether I apply the gradient with the tool, or ajust the spline heights at the respective ends to be equal, sometimes even when the track is laid level and all four spline heights are the same, I get the sag on one section. Can anyone explain why this happens and whether there is a solution, other than breaking up the run of track into smaller sections and thus risking an uneven appearance?
Parallel Splines Take Different Level
- Thread starter Vern
- Start date
Both tracks need to have identical vertex placements and if one track is 'straightened' then both need to be 'starightened' between the same vertex pair. Also worth checking that adjoining vertex pairs have identical elevations, this can catch you out on curved track using 'Apply Gradient'. If the same grade is applied to two parallel curved tracks the end point of the outer curve will be higher since the length of track on the 'outside' of the curve is longer than the track on the 'inside' of the curve.
On double track ideally use 'Apply Grade ' to one track, then set vertex heights on the second track using 'Get Height' and 'Apply Height' on each vertex pair...
Andy
On double track ideally use 'Apply Grade ' to one track, then set vertex heights on the second track using 'Get Height' and 'Apply Height' on each vertex pair...
Andy
steamboateng
New member
Another option is to lay the track grade first using any 2 or 3 track spline; use the "Smooth Spine Height" to adjust the grade, then delete the original spline and lay the track you want to use. Laying the track grade first allows adjustments through curves and bends, laying juctions on flat terrain, and a mutitude of other actions which can be tried and tested. Remember, the 'Undo' button is only inches away; something the real tracklayers and surveyors never got to invent!
Not being a complete noob to TRS route building 
I've been taking great care to ensure the relevant spline heights and/or applied gradients match and that the straighten tool is used where necessary. However the issue still occurs, you smooth one section of track with the tool and the adjacent piece is covered with terrain in the middle where the dip is (or if you smooth the dipped piece you get a terrain gap under the higher piece). Double checking the gradient and relative spline heights all match. Very odd!
I've been taking great care to ensure the relevant spline heights and/or applied gradients match and that the straighten tool is used where necessary. However the issue still occurs, you smooth one section of track with the tool and the adjacent piece is covered with terrain in the middle where the dip is (or if you smooth the dipped piece you get a terrain gap under the higher piece). Double checking the gradient and relative spline heights all match. Very odd!cascaderailroad
New member
Multiple tracks will have different spline point heights, as one track takes a shorter run around curves.
When laying a 4 track mainline I always lay a gradient on one inside track towards a mountain, and I stick with laying all gradients on that one track ... then I measure each track spline point heights on that gradiented track, and apply thet same height to all adjacent spilne points, all along the line. As on a gradient of an inside track of 1.45% ... the outermost track might have a 1.43% gradient.
When laying a 4 track mainline I always lay a gradient on one inside track towards a mountain, and I stick with laying all gradients on that one track ... then I measure each track spline point heights on that gradiented track, and apply thet same height to all adjacent spilne points, all along the line. As on a gradient of an inside track of 1.45% ... the outermost track might have a 1.43% gradient.
Not being a complete noob to TRS route building
Only one other possible culprit then - make sure you have 'Fixed Vertex Heights' checked (yellow track vertexes). If you are repeatedly 'smoothing' (only ever smooth once) and track vertexes are not fixed (white track vertexes) you are changing the track height with every application of the smooth tool...
Fixed vertex definitely on! I would say it tends to affect longer runs of straight track (say over 500m) rather than on curves. Just maddening when at End A both spline heights read 25m at End B both spline heights read 35m, the gradient on both tracks shows 2% (1 in 50) but when you hit smooth track the terrain promptly floods over the centre portion of the one section which has dipped relative to the other!