Fernbridge (bridge)
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Fernbridge | |
|---|---|
 Partial view of the west side of Fernbridge as seen from the south bank of the Eel River | |
| Coordinates | 40°36′51″N 124°12′8″W / 40.61417°N 124.20222°W |
| Carries |  SR 211 |
| Crosses | Eel River |
| Locale | Fernbridge, California |
| Other name | originally Eel River Bridge |
| Maintained by | California Department of Transportation |
| Characteristics | |
| Design | Arch bridge |
| Material | Reinforced concrete |
| Total length | 1,320 ft (402.3 m) |
| No. of spans | 7 |
| Piers in water | 8 during periods of high water |
| No. of lanes | 2 |
| History | |
| Designer | John B. Leonard |
| Constructed by | Pacific Construction (of San Francisco) |
| Built | November 8, 1911 |
| Construction start | March 20, 1910 |
| Construction end | November 8, 1911 |
| Construction cost | US$245,967 (equivalent to $8,043,000 in 2023) |
| Opened | November 8, 1911 |
| Replaces | an old ferry crossing |
| Statistics | |
| Daily traffic | 5650 (in 2022) |
Fernbridge | |
| Area | 1.4 acres (0.6 ha) |
| NRHP reference No. | 87000566[1] |
| Added to NRHP | April 2, 1987 |
| Location | |
 Interactive map of Fernbridge | |
Fernbridge, originally Eel River Bridge,[2] is a 1,320-foot-long (402.3 m) reinforced concrete arch bridge designed by American engineer John B. Leonard which opened on November 8, 1911[3][4] at the site of an earlier ferry crossing of the Eel River. Fernbridge is the last crossing before the Eel arrives at the Pacific Ocean, and anchors one end of California State Route 211 leading to Ferndale, California. When built, it was referred to as the "Queen of Bridges" and is still the longest functional poured concrete bridge in operation in the world.[5]
"It was generally believed that Eel River could not be bridged because its course changed so often."[6] Nevertheless, in 1909 the decision was taken to build a bridge at the Singley ferry crossing.[6] After 17 years of petitioning by Eel River valley residents,[3][4] Humboldt County Supervisors accepted bids for construction in 1910, and work started March 20 of that year.[7] The bridge is constructed of reinforced concrete because studies after the 1906 San Francisco earthquake showed that reinforced concrete withstood earthquakes.[3][4] The nearly one-quarter-mile (0.4 km) span cost US$245,967 (equivalent to $8,499,000 in 2025) to build, and consumed millions of board feet of local redwood timber for the framing. Construction was finished and the bridge put into operation on November 8, 1911.[7][8] As completed, the bridge had wooden trestle approach spans 500 feet (150 m) and 551 feet (168 m) long. The reinforced concrete structure was 1,451 feet (442 m) long overall with a 24-foot (7.3 m) wide roadway carried on seven 180-foot (55 m) long arches.[6][7] The original wooden approaches were replaced with the current concrete ramps in 1920[9] or 1918.[10] The south approach was again replaced in 1956 due to the flooding of 1955.[10]
Floods
The bridge survived floods in 1912, 1913, 1914, 1915, 1937, 1953, 1955, 1964 and 1986.[8] In the 1955 Christmas Week flood, the flood waters measured 27.7 feet (8.4 m) deep at Fernbridge. The south side abutment was washed out, and the approach damaged.[8] During repairs the first end span was removed and an earthen embankment was built which shortened the bridge by about 20 feet (6.1 m).[8]
Nine years later during the Christmas flood of 1964, every stream gauge on the Eel River was either inundated and useless or destroyed except the one at Fernbridge and nearly every bridge on the Eel River was badly damaged because the force of the water was aided by thousands of redwood logs stacked for winter mill production along the bank of the river as well as homes and barns swept away by the rapidly rising waters.[11] The flood peak at Fernbridge occurred at 4:00 a.m. on December 23 when the flood level was 29.5 feet (9.0 m).[11] The waters stayed high for 24 hours, and the discharge was estimated to be in excess of 800,000 cubic feet per second (20,000 m3/s).[11] A large island which had built itself upstream of the bridge was washed away in the wake of the 1964 floods.[8]
Historic designation
On September 24, 1976, the American Society of Civil Engineers designated Fernbridge as an historic civil engineering landmark and installed a plaque on the northwest approach pylon to the bridge.[12]
In 1987, the California Department of Transportation (Caltrans) recommended studying the removal of Fernbridge and replacement with a more modern span, such as the many which have washed into the Eel River during floods which Fernbridge withstood.[13] The Eel River regularly floods Fernbridge to the tops of the lower ridge of the support. In some high flood years, photographs have been taken showing the water level over the upper cone-shaped tops of the support pillars[14] as well as valley-wide flooding in 1915.[15] Residents of Ferndale successfully campaigned to stop any changes to the historic bridge. Fernbridge was added to the National Register of Historic Places on April 2, 1987.[1][6]
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