Plumas County, California Bridges: Marble Lane Bridge across the Middle Fork of the Feather River Overflow

November 2015 (39.76238, -120.33774) Marble Lane Bridge

The Marble Lane Bridge (09C0001) is a 285 ft long four span steel truss that includes a 100 ft long Pratt through truss span. The bridge is supported by large diameter steel pile extensions across the Middle Fork of the Feather River Overflow, which are several wandering streams near the headwaters of the river. The bridge was built in 1908 by the Canton Bridge Company in Ohio.

The Marble Lane Bridge is located in the Sierra Valley, an enormous meadow surrounded by mountains. You can see and hear long Union Pacific freight trains crossing over Beckwourth Pass just a little north of the bridge. This is considered one of the most beautiful and unspoiled areas of California.

This is a single lane bridge with an asphalt covered timber deck. The steel members came from the Cambria Steel Company of Johnstown, Pennsylvania. It's interesting how a bridge with steel from Pennsylvania and designers from Ohio got built in a high plateau in California. Since the bridge was completed in 1908, perhaps it was built to carry equipment for the nearby railroad that was being built over Beckwourth Pass.

Plumas County, California Bridges: Marble Lane Bridge across the Middle Fork of the Feather River Overflow by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Plumas County, California Bridges: Clio Railroad Trestle across Willow Creek

November 2015 (39.75342, -120.56772  ) Clio Railroad Trestle

This week we're going to look at another railroad trestle bridge on the Union Pacific Feather River Line. When the Western Pacific began building their line through the Sierras they abandoned the narrow gauge tracks of the Sierra Valley Railroad, turning railroad towns into ghost towns and turning Portola into a major railroad terminus between Oakland and Salt Lake City.  In order to maintain the 1% grade, the railroad built plate girder bridges on tall steel towers wherever they had to cross a canyon.

The Clio Trestle is 200 ft above and 1000 ft across Willow Creek Canyon. This part of the line (built in 1909) carries the railway east to the railroad depot at Portola, then over Beckwourth Pass, and into Nevada.

A trestle is defined as an open cross-braced framework used to support an elevated structure such as a bridge. It is undoubtedly an inexpensive way to carry a heavy train over a long, deep canyon but it's utilitarian appearance isn't very attractive. The philosophy that the most aesthetically pleasing structure for a site is the one that's most efficient at carrying its load is a nice idea that probably isn't true.

In the photo below two steam locomotives pull classic rolling stock (photographed by Randy Woods in 1991) across the Clio Trestle on their way west to the 10th anniversary celebration of the Sacramento Railroad Museum.

Plumas County, California Bridges: Clio Railroad Trestle across Willow Creek by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Plumas County, California Bridges: The Union Pacific 'Keddie Wye' across Spanish Creek

September 2015 (40.01886 Degrees , -120.95819 Degrees) Keddie Wye Bridges

South of the Spanish Creek Highway Bridge the Feather River Railway Line splits in two. A single set of tracks goes through Tunnel #32 and then widens into two sets of tracks onto bridges over Spanish Creek.

 The 'High Line' (built in 1931) goes to the north (to Bieber, California) where it connects to the Great Northern Railway (now the Burlington Northern Santa Fe Railway), which provides access to the Pacific Northwest. The main line continues west over the Sierras and to Salt Lake City, Utah.

The two bridges making up the 'Keddie Wye' are deck plate girder bridges supported on towers with single deck truss spans over the creek. The mainline bridge was built at the same time as the railway in 1909 and the branch leg (creating the 'Wye') was built in 1931. Each of the two segments of the 'Wye' are about 500 ft long across the canyon formed by Spanish Creek.

The Keddie Wye was named after Arthur W. Keddie, a Scottish surveyor who marked out the route over Beckwourth Pass and convinced the Western Pacific Railroad to complete their railway line across it. He felt that going over Beckwourth Pass (at 5000 ft) would result in savings by avoiding all the snow at 7000 ft high Donner Pass. However, less snow meant more rain and rock falls that required constant maintenance.

Today, the town of Keddie is a favorite spot for railroad buffs to photograph trains over the Wye. Occasionally a train headed west will wait on the 'High Line' while a eastbound train crosses over the creek. Eric Blasko took the photo below of three locomotives pulling the Overland Mail East across the Keddie Wye (from the book 'The Feather River Canyon, Union Pacific's Heart of Stone,' written by Steve Schmollinger). This book has been a good source of information while writing about the bridges of Butte and Plumas Counties.

Plumas County, California Bridges: The Union Pacific 'Keddie Wye' across Spanish Creek by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Plumas County, California Bridges: State Route 89 Bridge across Spanish Creek

September 2015 (40.0259, -120.9633) Spanish Creek Bridge

A little bit past Howell's Bridge the highway, railway, and river all split in different directions. State Route 70 continues along the North Fork but State Route 89 splits off, goes south, and eventually takes us to the Spanish Creek Bridge. 

After a month of looking at truss bridges it's a relief to enjoy the simple lines of an arch bridge. 

I was planning to photograph the old Spanish Creek Bridge (a deck truss that was built in 1932 on tall steel towers) but it had been removed after the new arch bridge was completed in 2012. You can see some views of the old bridge in the construction photos below (courtesy of the contractor, CC Meyers).

These photos show how the long arch was constructed. The first thing they had to do was pour the enormous thrust blocks on each side on the canyon. They rigged hundreds of tubes through each thrust block to pump cool river water through it and keep the mass concrete from cracking. Then the arch falsework was constructed and the formwork was placed on top. The arch reinforcement was put into position and the concrete for the arch was poured in segments. The concrete must have been pretty stiff to be poured and formed on the sloping formwork!

Once the two arch ribs were cured, strand jacks were placed on top and lowered the falsework and formwork to the ground. Spandrel columns were poured on top of the arches and falsework and formwork was set on the arches to carry the reinforcement and concrete for the deck.

I heard that the contractors were excited to be on such an interesting bridge, the work progressed smoothly, and the project won several partnering awards. That's a pleasant change from some projects where the contractor is always looking for a way to make money through litigation.

Spanish Creek is a seven span bridge with some tall and some very short columns. Since the bridge is in a seismic area the columns had to be designed to move together during an earthquake. If some columns were stiffer they would carry most of the inertia load and break. To prevent this, isolation casings were built around the columns next to the abutments to hold back the surrounding soil (see far columns in photo below). The supports at the top of the arch ribs are pedestals with bearing pads that allow the deck to move during an earthquake.

This bridge (as well as the previously studied Devil's Slide and Confusion Hill Bridges) was designed by Caltrans engineer Kevin Harper who has become a great designer of long span arch bridges.

Plumas County, California Bridges: State Route 89 Bridge across Spanish Creek by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Plumas County, California Bridges: Howell's (SR 70) Bridge across the East Branch of the North Fork of the Feather River

September 2015 (40.01420, -121.22580) Howell's Bridge

Howell's Bridge (09 0009) is a single span, steel 3-pinned, tied through truss arch. The concrete deck is supported with a floor-beam and stringer system on rubble masonry abutments. The bridge was built in 1933 and rehabilitated in 2002. The rehabilitation included replacing some of the rivets with high strength bolts and replacing the cross frames. The bridge carries State Route 70 along the north bank and over the East Branch of the North Fork of the Feather River.

It looks like everything on the arch is made out of built-up members. For instance, the hangers are made of a steel plate with two angles on each end to approximate a wide flange girder. In the plan drawing shown below, we can see the holes for the pins at the top and bottom of the arch that turn it into a statically determinant structure (that's easier to analyze by hand).

The arch descends below the horizontal tie to the abutment support (see drawing above and photo below), resulting in an eccentrically-loaded horizontal force on the arch from the tie.

In the photo below we get a nice view of the steel stringers supported by big floor beams and the hefty bracing where the arches meet the abutment. Note the flimsy ties, which are suppose to hold the arch shape like the string on a bow. Perhaps some of that force is being resisted by the abutments?

The last couple of photos provide views of the arch and its connection to the hangers and the bracing. We can see in the photos below that not all of the rivets have been removed.

These photos were taken from the extended arm of Caltrans' snooper truck (seen above), which is used to inspect many of the bridges along the Feather River Gorge. 

Plumas County, California Bridges: Howell's (SR 70) Bridge across the East Branch of the North Fork of the Feather River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.