Re: Soils and why fill a trestle? Not required reading.....

Hi Timothy. Worthwhile repeating here is the Exporail article you had posted in an earlier thread. [www.exporail.org]

Pages 195 & 196 (only about 1 page total reading) is an Appendix A to the main article, and is a 1909 piece that covers a lot of the points you mention. It wouldn’t be possible to tamp the fill dumped between trestle bents, so it was allowed to settle naturally over the many years that the original timber trestle still supported the track.

Interestingly in Jerry’s photo above, there is a fellow dragging the dumped material down the slope. CPR used to have whole gangs of navvies doing this, to make the side slopes more gentle than even their natural angle of repose.

Also on their Mountain Creek trestle on Rogers Pass, the CPR didn’t even need to haul the fill. It was available just a little higher up the mountainside, so they washed it down hydraulically as a soupy slurry. This was then carried to the trestle in a wood flume, that could be directed to the desired locations between the bents. The growing mound of fill was retained by coffer cribbing, the water gradually filtered away, and a nicely compacted fill was left in its place. Eloquent!

Cheers,
Ralph