Napa County, California Bridges: State Route 128 Bridge across Capell Creek

December 2013 (38.48389, -122.24222) State Route 128 Bridge

State Route 128 across Capell Creek (21 0078) is a three span continuous steel girder bridge built in 1956. Its 205 ft long with a 20 degree skew and an 80 ft long center span. The bridge has very tall two column bents with short pier walls at the bottom. The columns have a 'U' shape with the rounded ends on the outside of the bent (see bridge plan drawing below). 

I visited this bridge twice, but I had trouble photographing it because there was so much brush and water around it.

I reviewed the plans, which showed a 60" deep by 5/8" thick web with 12" wide flanges. The superstructure cantilevers 12' past the bents with a 56' long drop-in span set in the middle. The bridge was retrofitted with cable restrainers in 1983. New stiffeners and cross-braces were provided to the girders above the abutments in 1998 (perhaps 5/8" webs were too thin?). The backside of the abutments were also repaired. In 2003 the deck was cleaned, repaired, and treated with methacrylate.

The bridge was inspected in 2012 and was appraised as functionally obsolete with a sufficiency rating of 65 out of 100, perhaps because the deck is only 32 ft wide or because it's almost 60 years old. In the 2010 inspection report $1 million of work was recommended for 'general structural deterioration and inadequate strength.'

Napa County, California Bridges: State Route 128 Bridge across Capell Creek by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.