Best method for grading proto route

[Approach_Medium]

Hi;
I'm building a proto route. I have created the terrain using DEMs, and placed rail, road, and water using Google Earth and TransDem. Now all I have to do is grade my track (and roads). If I were to simply leave the splines as they were laid, the ride would be like a roller coaster. The DEMs cannot show cuts and fills for the trackbed, so I must create them.
My current method is to lay a separate track (I usually use an invisible track) from one point to a distant point, making sure that the endpoints of this single section of track are at the same level as the actual track I am trying to grade. Next, I get the gradient. Finally, I apply this gradient to each segment of track.
Using the Google Earth images I can usually determine whether there are tunnels or bridges. I am finding though, that often the track placement (by TransDem) is not as accurate as I would like, so I need to move the track to get a more realistic look (like where the track follows a river, I need to adjust the track up or down the slope of the bank to produce the least amount of cut or fill)

I am using 1arc DEMs for my terrain map. If I use 1/3arc I might get more accurate terrain maps, but for a large route, TransDem has trouble handling the 1/3arc DEMs (even though my sytem has 8GB RAM).
Is there a better method of doing this?

Thanks for your help

CP

 

[cascaderailroad]

I use wireframe mode alot, and dial the color (time of day to a dark chocolate color, easier on the eyes).

I never hit the smooth spline tool button until months down the road, and I leave the tracks submerged at almost all locations.

The first thing I do is sink all of the spline points to just a hair above the top of the terrain

First I lay my straights, and then connect them with curves, applying enough multiple spline points to make a perfect curviture

I always look straight down when laying track ... totally ignoring the track spline point heights ... I adjust the curves exactly, using a ruler

I also seem to have mastered using the little known about: "Get Curve Radius" button, and my curve radius are @ 300m to 500m

If the prototype has a track gradient chart, you use that approximate grade %, and watch your track spline point height arrows don't become way too low (deeper than @ 10m)

A gradient is not necessarily symmetrical throughout the entire line, as it will have various leaps and dips (but not like a rollercoaster.

Most of my gradients are generally @ 0.10% to 0.30%, and sometimes as high as 1.00%, but in mountainous areas never steeper than @ 1.75%

Months down the road you can press the smooth spline tool button

You can even use water as a visual guide helper, scrolling the water level up and down, to get a feel for the terrain

 

[SharkNose]

You can even use water as a visual guide helper, scrolling the water level up and down, to get a feel for the terrain

+1 :Y: An excellent idea!

 

[JCitron]

The problem with TransDem now is the initial files are so huge and difficult to manage. The NSGS has decided to flatten their services to 1 arc-second slices which for our purpose is too large. This makes the download files huge for the 1/3 arc-second resolution. With TransDEM it's a 32-bit application so it's restricted to the limitations of a 32-bit application. The files, as you've found out, are 400GB or large before uncompressing them and therefore they have to be chopped up into smaller chunks for handling.

Within TransDem, I don't bother to use the track spline tool. Instead I download topographic webserver images and overlay them on the DEM and trim out to that area. I then lay my track on the topomap and follow the rail line as printed. The 1/3 arc-second downloads combined with the images is fairly accurate.

When it comes to grades, I tend to be less accurate, although I don't have 2.0 % grades. What I do is average them out over long distances because we lose that fine resolution even at the level I work with. I use Google Earth to get the heights of the area I am working in and then smooth the grade between them. This may not be accurate but it works and avoids as you say the rollercoaster affect.

John

 

[bernhart_lossiemouth]

This Cascade Railroad deserves user of the millennium award. So helpful and knowlegeable. I made a banner of honor.

 

[Approach_Medium]

The problem with TransDem now is the initial files are so huge and difficult to manage. The NSGS has decided to flatten their services to 1 arc-second slices which for our purpose is too large. This makes the download files huge for the 1/3 arc-second resolution. With TransDEM it's a 32-bit application so it's restricted to the limitations of a 32-bit application. The files, as you've found out, are 400GB or large before uncompressing them and therefore they have to be chopped up into smaller chunks for handling.

Within TransDem, I don't bother to use the track spline tool. Instead I download topographic webserver images and overlay them on the DEM and trim out to that area. I then lay my track on the topomap and follow the rail line as printed. The 1/3 arc-second downloads combined with the images is fairly accurate.

When it comes to grades, I tend to be less accurate, although I don't have 2.0 % grades. What I do is average them out over long distances because we lose that fine resolution even at the level I work with. I use Google Earth to get the heights of the area I am working in and then smooth the grade between them. This may not be accurate but it works and avoids as you say the rollercoaster affect.

John

If you don't use the track spline tool in TransDem, then how do you lay your track along the lines shown in the topo?
I have been laying track in Google Earth as paths, then save them as .kmz files, and when I have the DEM opened in TransDem, I open the route from the .kmz files. Is there any difference between doing this and laying track in Transdem?

I've got a major problem with this route now, so I may be abandoning it and restarting the whole project.

 

[JCitron]

If you don't use the track spline tool in TransDem, then how do you lay your track along the lines shown in the topo?
I have been laying track in Google Earth as paths, then save them as .kmz files, and when I have the DEM opened in TransDem, I open the route from the .kmz files. Is there any difference between doing this and laying track in Transdem?

I've got a major problem with this route now, so I may be abandoning it and restarting the whole project.

That's bad news with your route. I hope you have backups somewhere. Perhaps it's too big and you need to carve it up a bit.

I use the graphics from the download topographic maps. I get these off of Microsoft's TerraServer, or (well used to until the shutdown) the USGS through the direct link. I then bring the route into Trainz Surveyor and lay my own track on top of the symbol that marks the tracks and put roads where the roads are. I have to zoom out sometimes to see the graphics clearly, but usually not. By doing it this way, I can also tweak the track as I go along especially where there are bridges and cuttings. I also found a stitch error between two parts of the same DEM. When the topomap is overlayed, the railroad and roads are off by about 30 meters. In my case, I just jog the track and blend the roads since I'm not being prototypical all the way with this project.

How do you save the .kmz files? I was trying to figure that out but I couldn't.

John