Uneven tracks on TransDEM created route

J

jeffmorris

Active member
I found out that there are uneven tracks on TransDEM created route. This is the first time that I used TransDEM to create a route. I'm trying to create a new version of Staten Island Railway. I know that some of the tracks are in open cuts and some tracks are "elevated". There's a short section of tunnel between Saint George and Tompkinsville. How can I fix the problem?
 
Although Transdem will lay track for you, this is intended as a rough guide and not a replacement for accurate placement and smooth gradient profiling etc. in Surveyor. In fact, when I use Transdem I don't even get it to lay splines, I simply lay my own track following the detail on the superimposed map and for the elevations then either read a gradient chart (if available) or best guess using lateral and vertical measurements if it isn't.
 
DEM's can be way off by +/-20' in either or all of the XYZ planes...or much much, more. HOG Tiger data lines can show rivers way up un hillsides, and rail lines in river channels. Unless it is done in 1/3 arc second data...a DEM can be extremely off and topography unprototypically distorted.

http://i525.photobucket.com/albums/cc339/cascaderailroad/DEMPRRTransdemHorseshoe1-3ArcSecond.jpg <---1/3 arc scond data

http://i525.photobucket.com/albums/cc339/cascaderailroad/DEMPRRTransdemHorseshoe3ArcSecond.jpg <---3 arc second data
 
cascaderailroad said:
DEM's can be way off by +/-20' in either or all of the XYZ planes...or much much, more. HOG Tiger data lines can show rivers way up un hillsides, and rail lines in river channels. Unless it is done in 1/3 arc second data...a DEM can be extremely off and topography unprototypically distorted.

http://i525.photobucket.com/albums/cc339/cascaderailroad/DEMPRRTransdemHorseshoe1-3ArcSecond.jpg <---1/3 arc scond data

http://i525.photobucket.com/albums/cc339/cascaderailroad/DEMPRRTransdemHorseshoe3ArcSecond.jpg <---3 arc second data
Click to expand...

Had that on an aborted French route I tried to make. No matter how carefully I georeferenced the maps, it was always off from the 90m SRTM (best available for Europe). For a US route it may be worth the OP setting up the WMS function in Transdem as I've found this binds the maps more accurately to the terrain than georeferencing downloaded 1:24,000 tiff files.
 
For the US I have tried USGS DLG vector data. Detail is identical to the USGS DRG 1:24,000 topo map. Such data perfectly fits onto a 1/3 arc sec NED DEM (10m).

However, 1:24k is still not a suitable scale for laying proper navigable track. And vector maps are usually 2D only. The height component for 2D data is taken from the terrain. Roller coaster.

Forget about TIGER in this context. The TIGER specs say 1:160,000. That's no more than a mere hint that there is some railway track somewhere nearby.

In the best case you have a special relationship with your favourite railway company and they provide you with high detail 3D vector data (1:1000). If you are that lucky, you can unleash the full power of TransDEM 3D track laying capabilities which include shaping cuttings and embankments (high fills) for you.

Edit:
Here is the "Truckee" example I was looking for:
http://forums.auran.com/trainz/showthread.php?p=51711#post51711
USGS DLG (railway track as vectors, but only 2D), USGS DRG 1:24k (raster map as ground texture) and NED 1/3 arc sec DEM. The perfect match.



geophil
 
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Is it possible to find the height of the terrain near the track and adjust the height of the track to match the height of the terrain?
 
Yes, but don't expect miracles. Usually, pure 2D vectors look better in Surveyor (vertices with white circular markers)

For DEM-based vector height you have actually two options in TransDEM, with slightly different results. Either in the vector export dialog, 2D group: "Adopt terrain elevation" or under the main menu "Route": "Adopt DEM elevations". The latter makes the vectors 3-dimensional within TransDEM, the former only for export.
 
I followed your instructions and got smoother track. I think that TransDEM 2.0 doesn't support multiple tracks. I tried to place a train on the track but the train is placed on the ground between two tracks. I had to replace the track in TRS2004 Surveyor. I had to create platform splines so that they follow the ground. Platforms created as scenery don't follow the ground.
 
Not realy sure what you mean...If you don't apply a smooth and simetrical grade to your track, and apply the "smooth spline" tool to make cuts and fills, your train tracks will be up and down like a rollercoaster, no matter how a DEM is made, or by whom,...DEM's are very rough, and inaccurate for RR grades. You have to smooth grades out yourself, tediously, by hand. Nothing is automaticly set up for you.
 
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How can I use a CAD program to create 3D vector data for track? There was a program called CAD2TRK but I think that it was discontinued and I think that it isn't compatible with newer versions of Trainz.
 
I would assume that the professional tools as used by the railway companies themselves would be capable of accomplishing this. I've been told there is a track geometry library for AutoCAD.

The screenshots of the Gotthard route on my website show track constructed with the Zusi 2 toolkit. Zusi is a German railway simulation. The Zusi 2 tools, however, are difficult to use. Moreover, there is only rudimentary English translation. Zusi 3, in the making for quite a while, will offer much better tools. It is unclear at the moment, though, whether these tools will be licensed for external use, such as with Trainz.
http://www.zusi.de/pages/dehaupt/zusi-3/programm/komponenten/gleisplaneditor.php (enlarge the screenshot of the editor to have a closer look at the gradient profiles)
http://www.zusi.de/pages/dehaupt/zusi-3/programm/screenshots.php
 
jeffmorris said:
How can I use a CAD program to create 3D vector data for track? There was a program called CAD2TRK but I think that it was discontinued and I think that it isn't compatible with newer versions of Trainz.
Click to expand...
Hi Jeff, not discontinued but reads and writes .trk file format from older versions - TRS2004/TRS2006. The newer versions of Trainz can read these older formats so you can still use it to make trk files they can use. However Cad2Trk can't read the trk files once save by the newer versions of Trainz so you can't make use of its append feature.

My program only translates the 2/3D vector data into a trk file format that Trainz can use. It won't create the track layout drawing for you. Any cad program that can export to dxf format can be used to create the track drawing full size (or a scaled version which the program will scale to real life full size). I use Cadrail, TurboCad and AutoCad. I like Cadrail but it has some limitations. It was developed to design model railroad layouts. I make up turnout libraries for the ng3 and sg and dual gauge track I work with. Most cad programs allow something similar. I stick to circular arcs and tangent track. Which is how real railroads are designed - connected with transition curves. Transition easments are possible but I find trying to implement them with Trainz track splines not entirely satisfactory. For dual gauge track I work mostly by running 2 track splines one visible that has the mesh for the full dual gauge and one invisible that carries the 3'ng. I draw one component and then make an offset copy at exactly 10.25" from it - towards the common rail. The limited amount of multiple track as you call that I've worked with I've drawn similar to how I draw the dual gauge - as a seperate centerline for eack track. Just starting with one track line and making offset copies at the required center to center spacing. The program then creates track splines for each centerline drawn. My program doesn't work with the kind bridge or multiple track that Trainz can use. I don't know about TransDem.

Developement of the program has been on hold for a long time now since Auran has seen fit not to publish the new map file formats. I've asked but Chris isn't symathetic, his path forward - as I understand it - is to provide some kind of interface to read the map files at some future time. Unless there's a facility to write and/or modify the new files it won't help me that much. Also it doesn't look like it's a high priority.

I'm retiring soon so maybe I'll have more time to bend his ear in the future and he'll relent or if not I might find enough time to hack the new map formats so I can continue to develope it. I haven't given up yet.

Bob Pearson

PS edit:
Here's some old pics from the EBT's Mt Union yard I stated some years ago. It's done mostly by drawing one track centerline and then making offset copies to draw the dual gauge and parallel multiple track centerlines. Invisible track splines used in the dual gauge are marked by the yellow splines in Surveyor.

http://i109.photobucket.com/albums/n74/EBTng3/MtUnion_yard/Screen_020.jpg
http://i109.photobucket.com/albums/n74/EBTng3/MtUnion_yard/Screen_015.jpg
 
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