Tuesday, December 6, 2016

Replacing the Wrights Bridge: Part I

Sixth Crossing, Los Gatos Creek

I love research because it convinces me to throw away perfectly serviceable parts of my layout.

Wrights, located at the top of Los Gatos Canyon, is a key scene for my model railroad. It has a photogenic location at the top of Los Gatos Canyon, with the tracks suddenly jumping across the canyon to dive into a tunnel. Photogenic structures - the old general store, tiny station, and abandoned warehouses - fill the scene. A siding, originally intended to go to the Sunset Park picnic grounds in the 1890’s, provides a way to hide a reverse loop at the top of the layout.

Original scene

The Wrights scene is also one of the earliest bits of scenery on my layout. During the first nine months of building, I focused on getting track laid all the way to my upper level so I could confirm that I knew how to build my two-level benchwork. Once the track was in, I decided I ought to do the messy scenery on the top level first; I’d hate to dump plaster on a good-looking scene below.

The resulting scenery was a mix of good and bad. I matched the rough terrain of the location deep in the canyon, and captured the look of both the redwood-covered hills above the tunnel and the creek deep in the canyon. I reproduced the wooden trestle from narrow-gauge era photos. I also made the model a bit "more interesting" with trestle bents that weren’t perpendicular to the rails, and a split-level concrete foundation matching an odd trestle bent I’d seen on Jack Burgess’s Yosemite Valley railroad. I also rushed construction of supports for the road bridge just upstream of the railroad trestle, plopping down plaster onto the hillside and shaping it to look like a massive concrete block supporting each bridge end.

Of course, then I started reading more about the actual location. Later photos showed a different bridge - a wooden truss bridge - in place of the trestle across the creek. I found some maps hinting that the road from the new Wrights station, on the other side of the creek, dipped under the bridge to make it to the road bridge and the road up-canyon to farms in Austrian Gulch and beyond. Adding that road was one of the few improvements to the scenes since 2006.

Then, last year, while searching up at the California State Railroad Museum, I found a little stapled set of blueprints, set up like Powerpoint slides. (I wrote a bit about those blueprints and maps I found back in August.) I’ve been claiming (without proof) that the booklet must have been the work of some summer intern in the engineering department. That intern had remarkably good lettering skills...

That booklet showed pictures and drawings of the actual bridge… which didn’t look anything like the actual bridge I’d made. Now, that’s not uncommon; I’ve found plenty of scenes on my model railroad that turned out not to match reality. In some cases, I ignore the mistake. Perhaps I needed to swap two scenes to fit my garage, or perhaps I believed the difference wasn’t noticeable. In other cases, I'm annoyed by the difference - but not so annoyed by the mistake that I’d do something about it.

And in some cases, I get annoyed enough to rip out completed, decent scenery, just to match details that the summer intern sketched out a hundred years ago, and stapled in a cool little booklet.

The Prototype

For the railroad, the bridge at Wrights was the “sixth crossing of Los Gatos Creek”. Los Gatos Canyon was an awfully narrow place to survey a railroad, and the railroad reached the headwaters by bouncing from bank to bank to keep grading costs low. Two of the bridges were just above downtown Los Gatos in the narrows at Lexington Reservoir. The third was near Alma. The fourth was near Aldercroft Heights. The final two crossings - just below Wrights, and just above Wrights - were the fifth and sixth crossings.

The South Pacific Coast Railroad laid all that track back in the 1870’s in their attempt to break the SP monopoly and get access to the lumber traffic from the Santa Cruz mountains. The SPC was narrow gauge - smaller trains and bridges kept the fledgling railroad’s costs low. Their original bridges met their “cheap” image, with most bridges being trestles with piles driven into the unstable soil holding them up.

The sixth crossing of Los Gatos creek, up by Wrights, was originally a trestle built on pilings by the South Pacific Coast. The tracks, on the east side of the canyon, suddenly made a right turn, cut across the creek and rolled across a filled-in gulch before diving into the mile-long summit tunnel. Photos from the 1880’s and 1890’s show a trestle that looks like it would have caught ever bit of debris rolling down the creek in the winter storms.

The SP leased the line in 1887, planning to make the line into a solid, first class railroad… eventually. When the plans to standard gauge the line started in earnest in the early 20th century, the SP widened the route and put in some slightly more solid bridges. SP finished dual-gauging the tracks to Wrights by 1903. The Wrights bridge, according to the intern’s slide deck, was replaced in the same year with a straining truss wooden bridge, built just as the tracks up to Wrights were being standard gauged. The intern described it as:

Old Structure. 80 ft. Straining Beam Deck Span on frame piers, with concrete footings with trestle approaches. Designed for narrow gauge track and equipment. Constructed 1903.
The plans to complete the standard-gauging of the line from Los Gatos to Santa Cruz got interrupted on April 18, 1906 as the Great San Francisco Earthquake hit the region. Landslides buried the track on both sides of the mountain, and the summit tunnel at Wrights was cut in the middle.

After the earthquake, the Southern Pacific spent three frantic years rebuilding the Santa Cruz branch. In Wrights, the railroad cleared and widened the summit tunnel, moved the station across the creek, and standard gauged the line. They didn’t replace the bridge, though, leaving the 1903 improved crossing in place.

And then we come to the project described by the intern. In 1915, the SP finally got around to improving both the 5th and 6th crossings of Los Gatos Creek. It wasn’t quite a new bridge; the intern noted that the new bridge was “Second Hand 50 ft Deck Plate Girder from the Santa Clara River (Montalvo Bridge). (Our 1915-vintage Sixth Crossing bridge was very lucky to get replaced and yanked out of Southern California. The bridge that superseded it was washed out to sea when the St. Francis Dam burst in 1928. Cue obligatory music.) The old wooden piers disappeared, replaced by a pair of concrete piers placed on the existing concrete foundations. Even if the bridge wasn’t local, the concrete was; gravel for the new piers came from Campbell, and the cement came from Davenport.

Road crossing under the bridge

The SP spent $6,556.98 on that new bridge: $3500 in labor and the rest on material, spreading the work over fourteen months from November 1914 to February 1916. The intern even broke down the costs - $1500 for the piers, $600 for the pilings for the trestle approaches, $700 to install the new steel bridge, $700 for the trestle approaches themselves, and $200 for ties and guardrails for the bridge. They also accounted for the corporate expenses - $500 for falsework, $300 for use of the work train, $600 for rental of equipment, and $180 to haul the materials up to Wrights.

Now, I just needed to figure out how to build that bridge to match the intern's drawings.

Coming up next time, I'll talk a bit about how I built the scene, and how many of the key parts of the scene were actually 3d printed.

Excerpts from blueprints were taken from "Sixth crossing of Los Gatos Creek Near Wrights", a booklet created by the Southern Pacific Coast Division engineering department to describe the project. Original in the California State Railroad Museum library, Sacramento.

1 comment:

  1. > "Photogenic structures - the old general store, tiny station, and abandoned warehouses - fill the scene. "
    Certainly one of the MOST modellogenic parts of the SPC...!!!