Grading track on DEM generated terrain

[Approach_Medium]

Hi;
I am building a proto route in TS2006 of the CSX River Line from Jersey City, NJ to Selkirk, NY.

I am at the track grading stage, and wondering whether there is a better way to get the correct grades for the line.

I have been pretty much relying on the DEM info I got from USGS Seamless Server, and Transdem's translation of this info for Trainz.
Sometimes though, it seems that my grade does not match what I know to be the correct one.

For example, there are areas where the tracks are in a cut, but if I grade below ground level to create the cut, then another section of track needs to climb too steeply to reach the proper grade further up the line.

I am assuming that my 1/3 Arc DEMs are not as accurate as I might need, but I am pretty much stuck with them.
I have been using Google Earth and MS Live Earth to get as much info as possible, but what can you really see from the angles of those images?

It would be helpful to get a really good topo map, but I have never seen one that shows cuts and fills for railroads.
My next option is to try to get a ride up the line, but even if I did know an employee or two, there is no way that CSX is going to allow a rider.
If there were an excursion, I would be on it, but there haven't been any up this line in at least 15 years! (Was one when the NRHS convention was in Bound Brook NJ, but I missed it

Any ideas on this?

Thanks

FW

 

[cascaderailroad]

DEM HOG/Tiger

Ahhh Yes...the ever present problems with DEM's...Firstly, the topography may be wrong in any of the x-y-z positions up to +/-20', or even greater, because heights of trees and buildings fowled up the DEM manufacturing...compounding that, the Hog/Tiger lines of a river may be way out of placement, and be incorrectly shown way up on a hillside. Track placement is too incorrect by +/- 20' in any of the x-y-z positions.

I (hold Shift Key) and place Quad mainline...keeping all tracks permanently separated...then, adjust track height to the aproximate heights and gradients, to get rid of the Roller Coaster gradients on the DEM. Most mainline gradients are less than 1.8%, and curves are generally greater than "200m R 15 degree fixed track". Don't press "Smooth Spline" button anytime...or it will permanently deform the DEM grid ! You will have plenty of time to use the "smooth spline button" a few months down the line, after you are satisfied approximating the gradients and curves. The "see through" "grid view" can be helpful for viewing buried track, and adjusting their heights.

I keep all tracks permanently separated, and never join them until the process is done to my own satisfaction and I am ready to join tracks, months down the line. After you are very satisfied with the gradients of the Quad line track...you can edit it out and replace it with the proper track of your own choice. Don't be in a rush to use the "smooth spline tool".

Just as the DEM was incorrect...on your finished route you may alter the prototype terrain significantly...but no one wil ever be able to tell if you do a good job on the terrain altering ! Never sweat the small stuff...and never let the DEM control your track laying. Use it as just a tool to get the approximate general idea of the prototype terrain.

Create a backup copy of your route in case you screw things up on the DEM's grid...so you can always revert back to an earlier original DEM. Never work on the Original DEM...only lay tracks the copy DEM.

My DEM has 4837 baseboards...how do you think I'm going to sort all that out ? lol

 

[markbin]

Yes, dems for steep lines are fun . In my Copper Canyon project ( Mexico ; 3 arcsec dems ) , i have not only to redo the grade of the 100 km 2,5 % rails , but also the river , and on top of that , rebuilding 10 km of mountains . ( not correctly fillled holes in the dem ).
The best thing that you can do is reading the hight of the rails in GE ( at regular intervals ), and put that on the maps that you use . Because the rails dont go all the time upwards at the same grade; they go up and down a bit in RL . So , when you make a 20 baseboards part of the line , you cant just use 2,5% over that whole traject.

 

[Approach_Medium]

Thanks for the advice/help.
cascaderailroad, you have hit my nail right on the head. In my last iteration of the route (in TS2009) I started to use the smooth spline tool right after grading.
I also made the mistake of importing the route from TS2006 to TS2009 to quickly, losing the Transdem interface, since it will not yet work with TS2009.

I assume you used the 4 track mainline to provide plenty of width along the route to accomodate sidings, etc.

As for the grade, I have been trying to stay below 1%. This line travels a long way along the Hudson River, where there isn't really any grade to speak of, but it starts and ends inland.

I see that there are 1/9 Arc DEMs available for some areas, but I don't think for my area just yet. I will check on that though.

I have all of the roads generated in Transdem (from GE maps) as well, but won't be worrying about grading them for quite some time.

FW

 

[cascaderailroad]

DEM's Hog/Tiger

Just remember to allways work on the copy of the DEM...and never on the original DEM...so you can revert back to the original DEM in case of mistakes.
I save my original DEM as a CDP for easy re-downloading should I decide to, rip up, delete, or start all over again, with my copy DEM.

 

[angelah]

WCL2

The dreaded DEM heights. Yes, I came across this on the WCL2 section. There are hills and a canal and river, so the DEM got really messed up. Heights were all over the place and it was a job to work out where they should be.
If you can get a route gradient chart then it would make to job a lot easier. Otherwise use your judgement - usually if it looks right it is!

Good luck with that...

Angela

 

[Approach_Medium]

Backups:
I've been making backups, and have the original DEMs backed up.
I save the route about every 1/2 hour, or even more frequently and always use a slightly different (I use name-date-time) filename to save.
Then I create a .zip to a backup removable HDD.

For grading, I am working with a lot of grade x-ings, so I try to have the track somewhere near the level grade x-ings so I don't have to alter the terrain drastically to get the roads to the correct height to cross the track.

Sometimes, to estimate the grade I need for a section, I'll run a separate (and different kind) of track alongside the route and set each end, then measure the gradient on it.
That works fairly well, as long as the section doesn't have a lot of bends.

This has been my method of grading for some time, but I thought perhaps there was a better, more accurate method.

FW

 

[Vern]

The 90m DEM's tend to average a fair bit, particularly near flat water - a steep sided gorge often turns into a hanging valley.

There is a website that sells the actual gradient profiles for many North American railroads (sorry I haven't got the link handy) as I bought one for the British Columbia Railway though never actually got round to using it in a project (yet). Where there's no gradient info I tend to measure along the track vector at 500 - 1000 metre intervals (depending on nature of the terrain) and extrapolate the required gradient from the vertical height change - always bearing in mind anything more than 1 in 50 (2.0%) for any distance will present a real challenge to prototype operation.

I used to get quite angsty if I couldn't find the actual gradient profile but tend to be a bit more laid back about it these days. IMO we are painting a picture of the route rather than an exact replica and end users are going to be extremely sad if they start pointing out your grade should be 1.5% not 1.7% or your summit siding is 100m off from reality.

 

[cascaderailroad]

DEM's

Grading Track-I have commonly seen gradients of more than %20 on alot of DEM's. This really poses a problem, and requires moving the spline points either up, down or sideways.

A maximum of 1.8% grade...and a "200m Radius 15 Degree Fixed Track" or greater, seem to be the norm for prototype RR's.

 

[sethmcs]

I grade track beds the same way the railroads did. Sometimes actually raising the track bed or lowering it as needed. Lowering or raising each 10m square by .2 or .25 and slightly lifting or lowering the track results in a 1% - 2% grade. Lotta work but yields excellant results.:wave:

 

[RPearson]

Grading Track-I have commonly seen gradients of more than %20 on alot of DEM's. This really poses a problem, and requires moving the spline points either up, down or sideways.

A maximum of 1.8% grade...and a "200m Radius 15 Degree Fixed Track" or greater, seem to be the norm for prototype RR's.

Real railroads moved a lot of earth grading the roadbed. As part of the grading they tried to even out the cut and fill volumes in local areas so they didn't need to import fill. 30m dems don't usually indicate much in the way of cuts and fills in the roadway. 10m dems show a bit more but it's mostly just an indication rather than the actual height of the roadbed. You've got to add most of these features back into the terrain. You can't let the track follow the terrain just as it is without working it to some extent and expect to get the same grades the railroad uses.

I'm modeling the 3ft ng EBTRR in south central Pennsylvania - not far from your area I think, Cascader. My 1st version was made with MD, HOG and 30m dems. I shifted the vector overlay images until I got good agreement with known features in the terrain - mostly larger creeks and rivers. I didn't have any info on the grades back then - it was a couple years before I joined the FEBT. I lay track using circular arcs, as good as I can lay them out, and tangent track between them. I don't go in for these long sweeping spline curves the Trainz track spline usually adopts. I generally followed the tiger data textured on the terrain and then picked off the ground heights along the track. I put the heights and track distances in a spreadsheet and used it to grade the route. I fixed a few locations I knew weren't going to move and tried not to go down into streams or up above ridge peaks. I programmed the spreadsheet to calc the grade between points and I adjusted the heights til I got the grades I thought looked good. I tried to keep the changes as small as I could and to even out the pluses and minuses locally but it was mostly trial and error iteration til I was satisfied. I set the spline pts to the heights I calc in the sreadsheet to set the grades. I ended up with the max grade of abt 2.6% on the southbound approach to Sideling Hill Tunnel. The 1917 EBT survey maps that I'm using for the current version of my EBT indicate the max grade there is 2.2%.

The grade maps in the EBT's 1917 survey indicate the original ground level and the track elevation and there's very little that isn't dug out or filled in.

Bob Pearson

 

[Vern]

Further to above, here is the link to the site that sells North American track plan and gradient profile info:

http://trainsite.8m.com/

The information is not cheap, particularly if ordering from abroad, but is very well presented and essential if you want a reasonably accurate route.

 

[HIgate4127]

Checkout http://www.railfandepot.com , I've bought many maps from them and never had a problem.

 

[backyard]

...I hope this helps...

Here's a couple of links to help...
Conrail 1999 Philadelphia Division Track Chart at RailFan Depot,

And a collections of pictures...
CSX River Line at Bear Mountain, NY by Christopher Muller