Bridgeport Covered Bridge, Bridgeport California

Date added: January 30, 2024 Categories: California Covered Bridges Howe Truss

Within a year of the discovery of gold at Sutter's Mill at Coloma in 1848, the population of California tripled. The urgent demand for roads and bridges was initially met by the establishment of privately financed ferries, turnpikes, and toll bridges. In 1850, John T. Little of Castine, Maine, built California's first covered bridge at Salmon Falls. By 1860, there were at least one hundred toll bridges in the gold mining region of California. The majority of these were timber truss bridges and, presumably, many of them were covered. Over time, however, the covered bridges were replaced with new structures, or lost to floods, fires, vandalism, neglect, or decay. By 1938 there were still thirty covered bridges in California. That number dropped to 17 by 1954. Today there are 9 historic covered bridges in California.

In 1849, gold was discovered along the South Yuba River in Nevada County, and a mining camp was established near this site. There was a bridge at this location by 1851, when miner Robert Wilson described in his journal crossing the South Yuba River near Bridgeport, "a little town at a bridge."

In 1856, David Wood and eleven associates formed the Virginia Turnpike Company for the purpose of building a 14-mile road from Anthony House, a stagecoach stop five miles south of Bridgeport, to North San Juan. According to this description in an 1859 report to the California State Legislature, a new bridge was built:

At about sundown we reached Wood's Crossing, over the South Fork of the Yuba River. Mr. Wood has, at large expense, built a most excellent mountain road, about ten miles long, one-half on either side of the river, and over the stream a firm, substantial bridge. For passing over the road, and crossing the bridge, each traveler, on horseback, is charged fifty cents, and those with vehicles in proportion, so that the outlay of ten thousand dollars proves a good investment."

In 1859, the Virginia Turnpike became part of a wagon road from Marysville, California to Virginia City, Nevada. Known as the Henness Pass route, this was the lowest and most heavily traveled road through the Sierras. At the height of the Gold Rush, as many as 100 wagons a day crossed the bridge at Bridgeport.

In the winter of 1861-62, massive floods washed out five bridges on the South Yuba River, including the one at Bridgeport. A few months later, the Virginia Turnpike Company rebuilt the bridge just below the old crossing. No details of the construction have been found.

The completion of the Central Pacific Railroad in 1869 drastically decreased travel on the Henness Pass route, although the Bridgeport Bridge continued to be used by miners. Decreasing revenues for the owner as well as public desire for free bridges eventually led to Nevada County's purchase of the bridge in 1901.

In 1948 the bridge was designated California Historical Landmark No. 390, but transportation safety issues continued to threaten its survival. In 1962, the bridge was slated for demolition, but historic preservationists fought to preserve it, raising the necessary funds for its rehabilitation in 1970-71. In 1973, the California Department of Transportation built a new concrete bridge upstream, and Bridgeport Bridge stopped carrying traffic.

In 1979, the California State Parks Department and Sequoia Challenge, a non-profit land trust, made an agreement to acquire and protect land along the historic river canyon. This led to the creation of the South Yuba River State Park in the mid-1980s. In 1984, the California State Parks Department purchased the Bridgeport Bridge from Nevada County. Subsequently, an existing ranch house was converted into a visitor center and ranger station.

Bridge Description

The Bridgeport Bridge is a single-span Howe truss wooden covered bridge with an auxiliary wooden arch. The total length of the bridge is 229 feet (portal to portal), with a clear span of 208'-0". The truss is approximately 18 feet high from the top of the upper chord to the bottom of the lower chord and 19'-0" wide overall, with a roadway width of 15'-6". Each truss has 24 panels and two end panels, each of the main panels measuring 8'-9" on center.

The Douglas fir trusses are framed in the manner patented by William Howe in 1840. The upper chord is composed of seven 3'x16" planks" laid flat and bolted together with ¾" diameter rods. The lower chord is comprised of seven 2"x15" planks fastened together in a similar manner. The chords are connected by paired 4½"x10" wooden diagonals (angling down and out from the center of upper chord), intersected by single 4½"x8" wooden counter braces, pairs of vertical 1¼" square wrought iron rods at each panel point, and 9½" x 14" vertical wooden endposts. The diagonals and counter diagonals are fastened together with 1" diameter threaded rods at their intersection. The end panels have single crossed 7½"x14" diagonals, notched and bolted together, and a pair of vertical rods next to the end posts. The diagonals bear on triangular cast iron thrust block assemblies at the upper and lower chords, while the rods pass through openings in the casting and through the chord, where they are fastened on the far side with a plate and nuts.

Each truss is flanked by a pair of auxiliary segmented timber arches. Each arch is comprised of 5"x13"x20' timbers, butted end-to-end, and fastened to the diagonal truss members with threaded rods and nuts. There are wooden spacer blocks wedged between the arch and counter diagonals. The arches spring from cast concrete skewbacks on the face wall of the abutments, rise approximately 20 feet to the crown and span 208'-0". The arches are tied to the skewbacks with steel plates and rods.

The lower chords of the bridge rest on wooden bolster beams (6"x12" timbers bolted together) on top of the abutment face walls. The mortared stone abutments appear to have been rebuilt at an unknown date. At each panel point, a 12"x12" transverse floor beam is bolted to the bottom of the lower chord. There are nine lines of stringers laid longitudinally on top of the floor beams. The deck is two layers of 1½"x11" plank flooring laid diagonally on the stringers, with longitudinal running boards on top.

The roof system (all new) bears on 3"x12" tie beams below the upper chord at each panel point. Lateral bracing consists of 3x8" timbers notched into the upper chord at every other panel point. The rafters frame into the upper chord and are spaced approximately 2 feet apart. There are collar ties between the rafters. The gable roof is covered with wood shingles fastened to longitudinal wooden purlins (spaced at 2-foot intervals) on top of the rafters.

The bridge's exterior is covered with wooden sugar pine shingles to the eaves, with the outline of the arch clearly visible. The shingles are fastened to ¾"x2½" lathes on 1¾"x3" vertical nailers on the exterior faces of the trusses. The portals are straight with squared openings, open gables, and heavy timber sway braces between the end posts and the tie beam. There are three 30"x33" window openings on each side of the bridge, in the center panel and the fourth panel from each end.