Embankment versus trestle

[schweitzerdude]

Assume a railway is building a single track line across mostly level terrain, but is faced with an increase in elevation maybe a km or 2 ahead. To avoid even more curves on the higher areas, with related cuts and fills, it seems to me that they might want to get a head start on the level part by using fill and building an embankment to start gaining altitude, so that the gradient nowhere exceeds 2% and the overall construction cost is as low as possible.

But there might be a point where the embankment would be too high and a simple trestle would be more economical. I'm faced with this on a route I'm working on (using Transdem generated terrain) and wonder what a real railway would do - at what height above ground would a trestle be more economical than an embankment?

(assume no canyons, creeks, etc are an issue)

 

[cascaderailroad]

Backwoods NG RR had no money to build expensive high trestles, (there are some rare exceptions).

Usually a RR followed the path cut by a prehistoric river, and they cut a shelf out @ 30' above flood level. Take on the Horseshoe in Altoona, they made cuts, and fills everywhere, sometimes being pieced by a river tunnel or viaduct.

 

[bl4882]

I don't know that there is a rule that governs. Out here in the Wild, Wild, West, where wood was plentiful, trestles were often built and over time filled in with earth. The earth required less maintenance and would be sturdier over time. Some of the older routes show incredible fill work. Note this: Once was a trestle, now is tons and tons of earth

It's also beautiful. :wave:

Bernie

 

[bl4882]

Note also, the angle of repose is about 40 degrees or less.

Bernie

 

[Euphod]

I would choose embankment over trestle unless a ravine or body of water stood in the way.

 

[bl4882]

Only if you were a robber baron. :hehe:

Bernie

 

[Euphod]

I prefer to think of myself as a 'robber viscount'...

 

[bl4882]

Well done! Now I retire to Dvorak and Mahler.

Night all.

Bernie

 

[bendorsey]

Some eastern roads filled in trestles too. I've been over a few (long ago).

Ben

 

[Euphod]

Well done! Now I retire to Dvorak and Mahler.

Night all.

Bernie

Although I like some of Mahler, in truth I'm more of a Smetana devotee.

 

[Pencil42]

Here's a pic of Chinese workers filling in a trestle on the old Central Pacific...
http://www.irwinator.com/124/EE4e/14-5.JPG

 

[cascaderailroad]

In Altoona a want add was posted: "Need 100 strong men to fill in the Sandy Gap trestle on the Wopsononock RR" ... pay was rediculously low in 1899 ... like $5 a week for grueling labor.:hehe:
http://wopsylady.webs.com/apps/photos/photo?photoid=59537674

 

[Euphod]

Here's a pic of Chinese workers filling in a trestle on the old Central Pacific...
http://www.irwinator.com/124/EE4e/14-5.JPG

That's a great picture, thanks for posting it!

 

[H222]

Maybe a spiral up?? If it's fictional

Jamie

 

[wreeder]

During the building of the Rio Grande Southern, many small trestles were built (some as low as six feet) that spanned minor depressions. This was done to get the line open as soon as possible. There were also many large trestles that were built to span gaps between the ledges that had been blasted out of the hillsides to keep the gradient to a minimum. Over time many of the trestles were buried by dumping rock and soil from the top of the trestle. This debris often came from clearing landslides that blocked other areas of the line.

William