JF Ptak Science Books Quick Post
“Exceptionally Large Trestle Fill” is the rather Engineeringly Prosaic header for this Popular Mechanics article from March 1912. The 4,869′ span was at Sprague Gulch, “near Lamont, Washington” for the Spokane, Portland & Seattle RR, stood 101′ above the water (at its highest), and the idea was to backfill a foundation for stability–a project that was found to be cheaper than building a steel structure.
The trestle was built in 1907 and the backfill begun in 1911–a project that would ultimately move and deposit 2.35 million cubic yards of earth. The process called for the construction of two temporary trestles at levels approaching the permanent track–the last bit of fill would take place from finished level. This is just a beautiful project.