Gradients in the USA

[Weezknight]

Is there a website, or a book I'm supposed to be visiting to get gradient profiles in the US? I know I've seen UK designers talking about books and such, but didn't know if similar resources were available here in the US.

I'm working on a route, and the DEM data imported fine, but I'm guessing I'm not supposed to just lay the track willy-nilly on each sloping surface, there has to be some rhyme or reason, right? I understand the idea of laying my tracks and then bringing the terrain up to meet the track, where the terrain is lower, but is that realistic? I'm sure, at some point, the route I'm planning goes downhill.

[BlueLight]

I'd start my research at the USGS web site.

[barnez]

See if you can get a trackchart for your route. Trackcharts show complete gradient & elevation data - then you can adjust the terrain to the track & easily create any berms or valleys that the line runs through.

Even a fairly old one will probably do as the overall gradient for a route is unlikely to have changed much if at all in the past 20 years or so.

www.railfandepot.com has a number of charts both print and digital for routes in the US.

-barnez

[Weezknight]

Thanks for the tips.

Looks like I may be headed to the Library. The last track chart that surfaced for this route (old short line) sold on eBay for a couple hundred bucks, so they are rare to find. I was able to find a drawing that a worker did years ago. At the very least it shows the original speed limits on the line, and where some of the old, now abandoned, sidings used to hide.

If nothing at the Library pans out, I may just fudge things by doing a simple gradient calculation between at-grade crossings & stations, since the elevation data I have for those locations is pretty spot on.

[GreatNortherner]

Hi,

Old topo quads are also usually a good source to estimate the gradient of a railroad line if an actual track chart cannot be found (or is too expensive). With the height lines you can measure the height difference, and very often larger cuts or emankments are also shown on the profile.

There are various places where you view historic topo maps online, for example this one:
http://historical.mytopo.com/index.cfm

Michael

[hertsbob]

the elevation data I have for those locations is pretty spot on.

Trust me. That's all you need.

Put yourself in the mind of the 19thC surveyor. "That station is x feet higher than where I'm standing so I need a 0.9% grade." Job done.

Even if you have an accurate gradient profile (or whatever you call them) you'll still end up with areas where the DEM terrain doesn't match up. So don't worry about it. Go with the flow.

[Bananarama]

The last track chart that surfaced for this route (old short line) sold on eBay for a couple hundred bucks, so they are rare to find.

Some free:

Multimodalways: http://www.multimodalways.org/archives/rrs/rrs.html

Some Payware:

Railfan Depot: http://www.railfandepot.com/servlet/StoreFront
Railroad Paper Collectables: http://trainsite.8m.com/

Else, you might find something in one of the Yahoo railroad groups (search for named railroad: http://groups.yahoo.com/). Good luck!

[emdsd90mac]

Is the route fictional or prototypical? If it's fictional, you can probably SWAG most of the grades keeping in mind not to make them too steep. I think the steepest grade on the Mojave Sub is 2.2%. If it's a prototypical route then you might be able to figure out the grade using Google Earth and some math. A 1 foot gain in elevation over a 100 foot span of travel equals a 1% grade.

[Bananarama]

There's also Fog Charts: http://www.fogchart.com/FOGCHARTED.htm

Keeping in mind that the data is approximate.

[emdsd90mac]

Oh come on, GE is always accurate right? LOL