|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.
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!
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.
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.