Better method to set gradient?

[Approach_Medium]

Hello;
I am working on a large route (yet another one), which has been generated from DEM files using TransDem.
I've got my basic track running through the terrain, and am now in the process of creating realistic grades.

For lack of a better tool, I am simply laying out a temporary section of track over a given distance (usually between two curves) and setting the height of the splines at each end of this temporary track to that of the actual track.
Then I click the get gradient tool at the start of the section of temporary track, and apply that grade to the real track along this section.

It would be really nice to have a set gradient tool that would work by dragging along a section of track, then indicating the grade between the two endpoints, and allowing the surveyor (you) to accept and apply the grade, or to modify it.

I am going to post this in the suggestion boxcar.

What do you think? Do you have another trick?

Thanks

FW

 

[cascaderailroad]

Generally (unless its a mountain logging RR) a gradient should be not be more than 2%. Most prototypes are 1% or much less. I lay the track and curves looking from directly straight down, (with the line -surveyorfov=150 entered into my trainzoptions file). Once you are satisfied with all the straights and curves, try by trial and error, try raising the grade. Never hit the Smooth Spline tool button ! If you do...press "Undo". Use wireframe mode to see where the buried track is, and how much it needs to come up. I have found that on my Horseshoe Curve route the grade to the summit is not just one single 1.25% grade ! Instead it is various gradients, with dips and sags every once in a while...the world is not flat..and grades are not always consistant. Only after you are satisfied with all your gradients and curves...then is the time to hit the Smooth Spline Tool Button. You can always press: "Undo". The raise/lower track tool button where you tug up and down on a track, is a skill only mastered by trial and error and lots of patience.

Never use multi or double track splines...as they refuse to cooperate in laying gradients with single tracks ! Always use single tracks throughout a route ! The only thing multi-track splines are useful for is: using it as a gauge, to set the preliminary distance between adjacient tracks. Then delete the multi-track spline and replace each track with single track.

 

[Approach_Medium]

with the line -surveyorfov=150 entered into my trainzoptions file

What does this line do?

I guess I could also use the ruler along the track, then calculate the grade.

FW

 

[gfisher]

I don't understand what you are saying here. There is a set gradient tool and you can set it to any grade you want for any section of track between two spline points.

 

[Approach_Medium]

I don't understand what you are saying here. There is a set gradient tool and you can set it to any grade you want for any section of track between two spline points.

I have a prototype route that I generated using DEM data and TransDem.
I have the track laid by TransDem, but the track originally follows the contour of the terrain. I need to create the proper grading for the track, making cuts or fills where necessary, since DEM data does not show this detail.

What I have been doing to get the grade as close to prototype as possible, is taking one section at a time. Sections contain between 3 and 10 or more spline points, depending on the curvature of the track.
I basically average the grade between the start and the end of the section.
I have been doing this by laying a temporary track alongside the actual track, set it's end points elevation (this temporary track has only the two required spline points) to the same as the spline points at the same location on the real track. Then I use the Get Grade tool on the temporary track to get the gradient that I should use on the real track for all segments between the start and the end.

This method has generally worked for me, producing the average gradient over a long segment of track.
If I find that I end up with a cut that is more than say 50 feet deep, I will re-do the gradient to allow a rise, then a fall in elevation to reduce the cut depth. Same thing if I get too high of a fill.

Since I cannot see this detail using Google or Bing aerial maps, and I cannot ride the rails in these areas, this is the best method I have come up with.

Sometimes I manage to get actual track maps, which contain gradient info, but this is rare, as RR employees are prohibited from selling or giving this information away.

If there were a tool that would collect data over a given section of track (one containing many spline points) to average the grade, then applying the given grade would be much easier.

Perhaps I could use a locomotive running over the track sections, then collect and save the gradient data. I have seen this information displayed in some of the built-in sessions in TS2010, so I know that it can be done. The only change I would require for this is to record this data to a log file, so I could read over it at the end of the run.
This would give me a method to average the gradient, and then set that gradient for each spline point I have just run over with the locomotive.

When I am creating a non-proto route, there is no need for this, since I would just lay the track on the flat baseboard, apply the gradient I want, then create the terrain around the track.

I hope that I haven't confused anyone with all of this.

FW

 

[Jayturf]

It seems to me you already have it figured? Doesn't sound like you need a better method. I am currently in the process of grading my 350mile route and I do not use the smooth spline as it creates a WAY too wide cut or fill... I have already hand graded 275 miles of track!

When I make a transdem map I do not use the track spline option. Instead I just draw out my route and use it as a guidline for my finished track. I find that if the program lays the track it is way off and I end up having to redo it all anyways.

I use a similar method to get average grade although I have known elevations at given mileages so that also makes it easy. I also have data on the ruling grade which is 2.2% on my route. Intersting fact, the route i'm modelling (Kettle valley railway) has one of the longest grades over 2.2% in north america at around at 27 miles. And it isn't intermittent either...it is a constant 2.2%.

Another thing that I do which the real surveyors do is compensate grade on curves. Since it requires more energy to pull a train around a corner the grades were lessened on them. I use a 0.1% reduction for a moderate curve and a 0.2% for sharper curves. This results in great performance.

It would be nice however to have it automatically set the grade and compensate for curvature as you lay the track...say you would set your grade for 1.2% and then the next spline point you laid would automatically be on a 1.2% grade from the last spline point...that would be fantastic!

 

[RPearson]

FW said-> Perhaps I could use a locomotive running over the track sections, then collect and save the gradient data.

I think this is possible if you write a custom script. It would simply get the grade under the loco or train car (method provided in the vehicle.gs script) at specific time intervals. Distance is not as easy to get but can be obtained from with a track search function. Junction, industries, crossings and a few other thing make the programing a bit complicated. It's also possible to get train speed when the gradient is sampled and integrate it to get a close approx to distance traveled.

Writing it all out is a bit clumsey. Has to be written to the jetlog.txt file and then you can edit that to extract the data you need. I do things like that for testing steam locos and extract the data with scripts I write using Python - a general purpose scripting language.

You could probably incorporated track marks/triggers to id specific points on the track. It would be a nice project for someone to do maybe.

Anyhow - more than one way to get things done.

Jay said-> Another thing that I do which the real surveyors do is compensate grade on curves. Since it requires more energy to pull a train around a corner the grades were lessened on them. I use a 0.1% reduction for a moderate curve and a 0.2% for sharper curves. This results in great performance.

This is now a consideration in Trainz since TS2009 (actually I think it was in TC1 or 3) when they incorporated curve resistance. Prior to this curves had little impact on resistance. Curve resistance in Trainz appears to follow the usual expression of C lbs/ton/deg of curvature. C is usually between 0.7 and 1.0. A typical figure for compensating grades on curves is to reduce the grade 0.035% (based on C of 0.7) for each deg of curvature. Deg of curvature for the above would be 5730/R with R the radius of the curve in feet. Of course I'm an old guy stuck in the world of US customary units. Trainz internally uses metric units.

Bob Pearson

 

[Jayturf]

This is now a consideration in Trainz since TS2009 (actually I think it was in TC1 or 3) when they incorporated curve resistance. Prior to this curves had little impact on resistance. Curve resistance in Trainz appears to follow the usual expression of C lbs/ton/deg of curvature. C is usually between 0.7 and 1.0. A typical figure for compensating grades on curves is to reduce the grade 0.035% (based on C of 0.7) for each deg of curvature. Deg of curvature for the above would be 5730/R with R the radius of the curve in feet. Of course I'm an old guy stuck in the world of US customary units. Trainz internally uses metric units.

Bob Pearson

Is there an easy way to get the radius of a curve in trainz that doesn't involve measuring every corner. I think it would be nice if you could do like a track properties that would tell you that kind of info!

 

[RPearson]

Well you learn something new occasionally. I always thought that it showed spline curvature which is reciprocal of radius. I just checked the TS2009 copy I have installed and on the track tab under advanced options at lower right of the panel is a button that shows the curve radius. Hit the button then place the cursor over a track spline and it will display the radius at that point. This value is always displayed in meters regardless of units settings for the route. For straight track it shows a radius of 0 which is not correct - it should be infinite. I think that's why they used to show curvature as that is 0 for straight track and a finite value for any track curve.

Anyhow you'll soon discover that the cubic spline used for the track in Trainz can't exactly duplicate a circular arc. The radius varies constantly along it rather than a fixed value. Generally with precise placement of vertices - beyond what you can do manually in Surveyor - you can reduce the variations to +/-5% of the radius or so.

Bob Pearson

 

[narrowgauge]

Bob

This is now a consideration in Trainz since TS2009 (actually I think it was in TC1 or 3) when they incorporated curve resistance

I struck that problem during the development of TS2009, a train that in TRS2004 could negotiate bend at slow speed, completely stalled in TS2009. Admittedly, it was a 2 foot gauge line with 10 metre radius bends, corners is the more realistic description, the prototype had them so did we.

Nobody mentioned that curve resistance was built in and was the cause.

Peter

 

[Jayturf]

WOW...i did not know that tool existed!!! now I have to go and do all my corners on my 350 mile route!!! haha