Fill_000

Cuts and fills are essential railroad right-of-way engineering. Without fills tracks crossing uneven or hilly terrain as shown here would require mile upon mile of costly bridge, trestle and other structural work. Fills eliminate these expensive to build and maintain elements. However, fills are also complicated structures having their own construction¬†principles and guidelines to ensure stability. It’s hardly as simple as piling up a bunch of dirt or rocks and laying track on top.

The fill shown in these first two photos illustrates several important features modelers might want to pay closer attention to. First, although I’m hardly a structural engineer, I suspect that the material used here is a mix of different size rock, with fines and other granular material that allows for compaction. This is important for the stability of the track and traffic it carries. This right of way dates back to the steam era and I suspect this fill has been re-engineered somewhat to carry modern loads (that’s speculation on my part). Notice how much slope there is to the material. This is called the angle of repose, an angle at which a given material will naturally come to rest and be stable. (Correct me as needed Will.)

Fill_001

You’ll also notice the railroad has cleared trees and other brush away from the tracks. They’ve done this along much of the line this year. It has been a very dry summer for this region in 2012 and preventing brush fires may have also been a consideration in clearing away encroaching vegetation. Looking in the opposite direction in the photo below, you can see the scars from construction equipment and other work performed in this area. Take note of the washed stone that was brought in as a paving surface keep equipment out of the mud. Notice how rough the foreground is and the mix of live and dead vegetation compared to the area in the distance.

Fill_002

In this photo below take note of how deep the ballast is and how generous the ballast shoulder is. You can see what looks like a bit of dirt peeking through in the foreground. Probably a result of all the work in the area.

Fill_003

Finally, looking west again, you see how shallow the slope of the bank is compared to the near vertical cliffs typically modeled because we don’t leave enough space to do it right. You can also see how much brush and debris remains from the clean-up efforts. Observe how the base material was formed into a pad for the crossing flashers and the ever present drainage path for water runoff. The road crosses the track at an angle and the crossing protection is aligned for the motorist’s visibility. Observant eyes will also detect how the original terrain contours flow from one side of the road to the other. You’ll also notice how far back the utility poles are from the track.

Fill_004

And last, but certainly not least, the track has a distinct tinge of color from the oil and grease drippings of many passing trains. All of these features and more, are easily modeled once you know they are there.

Regards,
Mike