The smaller fills on the Death Valley RR do not appear to have had culverts beneath them. The area drained by them was relatively small, so most likely the porous nature of the fill would let water seep through.
We hiked about 1/4 mile upgrade from the previous large trestle to the next trestle site:
This was the largest trestle on the DV RR. Here is a photo of it in 1914:
The photo is looking to the south. The photographer's photo site would have been on the right hand side of my photos.
I walked a little way down to see the bottom of the canyon:
At some time during its use, the trestle was filled in. You can see the large drainage pipe installed as part of this process. Sometime after abandonment the drainage pipe must have become clogged and the fill washed out. You can see this location on Google Earth:
DV RR Largest Trestle Site
The Death Valley RR had a couple dozen small pile trestles crossing arroyos, and at least three large trestles on its way to Ryan(there may have been others which were filled in). Although the trestles are all gone, most of the ROW is in excellent shape.
More later...