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Yosemite Roads and Bridges
Yosemite National Park, California
YOSEMITE'S BRIDGES
A variety of vehicular bridges span the main streams and lesser tributaries in the park. The oldest is the covered bridge at Wawona, built as an open-deck structure in 1868 by Galen Clark, the first settler and state-appointed Guardian of the Yosemite Grant. In the 1870s it was converted to a covered bridge by the Washburn brothers, natives of Vermont, who supposedly had it altered to remind them of their home state. Rehabilitated by the Park Service in 1956, it can be seen today at the Pioneer Yosemite History Center.
Wawona Covered Bridge, 1868. Drawn by Dione DeMartelaere, HAER, 1991 |
Over the ensuing years more timber and iron trusses were built, but these eventually gave way to reinforced concrete structures; of the latter type, Sentinel Bridge (1919) and old Happy Isles Bridge (1921) remain. Many of the park bridges appear to be of solid stone-masonry construction. Actually, these arch bridges are concrete and merely faced with stone in the characteristic Rustic Style of architecture employed by the National Park Service.
Three park bridges built in the 1930s appear to be constructed of large logs, but are in fact built of steel and concrete. Native log siding conceals the modern structure from the visitor's view. Most noticeable of these spans is El Capitan Bridge, built in 1933; other examples are found on Glacier Point Road and in Yosemite Creek Campground.
Early bridges were wood and metal trusses. The previous Sentinel Bridge was an uncommon iron bowstring-arch truss. YRL |
On Big Oak Flat Road three open-spandrel concrete arch bridges were constructed in the late 1930s over Cascade. Wildcat and Tamarack creeks, marking a departure from earlier Rustic Style designs.
Two recent structures, Cascade Creek Bridge on El Portal Road (1984) and a new Sentinel Bridge (1994), represent an attempt to revive the earlier rustic stone-faced designs.
Three side tunnels or adits provide ventilation. The central adit contains three 8-foot diameter exhaust fans, activated by carbon dioxide detectors, to remove harmful gases. Photo by Brian C. Crogan, HAER, 1991. |
The Wawona Tunnel was the longest vehicular tunnel in the West when completed in 1933. Significant for its state-of-the-art engineering, the tunnel played a greater role in preserving the visible landscape of Yosemite Valley.
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