The Lesser Spans – Benicia-Martinez-Bridge

October 3, 2015 | By | Reply More

CarqThe first of the San Francisco Bay’s high – level bridges was the spectacular four – thousand – foot cantilever structure built in 1927 across the „inner Golden Gate“ at Carquinez, with a three-lane deck high enough to allow the passage of ships to Stockton.

It was the first bridge in the world specifically designed to withstand earthquakes.

The name originally referred to the original single steel cantilever bridge which was designed by Robinson & Steinman and dedicated on May 21, 1927.

It was built to form a direct route between San Francisco and Sacramento and spanned the Carquinez Straits between Vallejo and Crockett.

800px-The_Carquinez_BridgeIt was the first major automobile bridge crossing of the San Francisco Bay and a significant technological achievement in its time.

Traffic aross the Carquinez Strait was before by steam ferry. For decades, building a bridge here was considered prohibitively expensive and technologically risky. 

The bridge had been the brainchild of Aven J. Hanford and Oscar H. Klatt, operators of the Rodeo-Vallejo Ferry Company.

The growth of automobile traffic had caused a ten-fold increase in the number of vehicles using Hanford and Klatt’s auto ferries in the five years from 1918 to 1923.

The need for a bridge across the Straits became obvious and the two partners formed the American Toll Bridge Company to undertake the project.

800px-Alfred_zampa_memorial_bridgeGround was broken in 1923 and construction took four years.

The new bridge was described at the time as a “majestic masterpiece of engineering” and was heralded as the world’s largest highway bridge.

When it was finally completed in 1927, the total length of the new bridge was 4,482 feet and the main support towers stood 325 feet above the water. 14,000 tons of steel were used in the project and five steel workers lost their lives during construction.

On March 19, 1927, the final section of the span moved slowly up the Carquinez Strait on barges.

Massive counterweights were suspended from the already completed portions of the bridge and were slowly filled with sand. As the counterweights eventually increased to 750 tons each, the span was slowly hoisted on cables into position. This spectacular engineering feat was completed in less than an hour.

Two months after the final span was lifted into place, the Carquinez Bridge officially opened. Thousands of people attended the ceremony on May 21, 1927.

The governors of four states – California, Oregon, Washington, and Nevada – were on hand for the dedication. The great celebration was nearly eclipsed by other momentous news, shouted by newsboys hawking their afternoon papers on the bridge.

800px-Carquinez_Strait_aerial_viewAmerican pilot Charles Lindbergh had reached Paris, completing the first solo trans-Atlantic airplane flight.

Following WWII, California’s population continued to boom. The nation’s interstate highway system expanded in response to America’s increasing dependence on the automobile.

The Lincoln Highway was the first road across America. Its original alignment from Sacramento to San Francisco avoided the un-bridged waterways of the San Francisco Bay and the Sacramento Delta by routing itself through the Altamont Pass and the central valley.

A second parallel cantilever bridge was completed in 1958 to deal with the increased traffic.

Later, seismic problems of the 1927 span led to the construction and 2003 opening of a replacement: a suspension bridge officially called the Alfred Zampa Memorial Bridge, after an ironworker who worked on a number of the San Francisco Bay Area bridges, including the Golden Gate Bridge.

  • The new Carquinez suspension bridge is the third bridge at this site and replaces the existing bridge, built in 1927. It carries traffic westbound on I-80.
  • The three-span 1,056-metre long structure was the first new major suspension bridge built in 35 years.
  • The bridge features two 125-metre high concrete towers, supported by 3.0 m diameter piles of 90 metres length and a 25-metre wide deck.
  • The bridge is designed to withstand quakes of 8.0 on the Richter scale.

The 1927 span of the Carquinez Bridge is featured on a Season 4 episode of MythBusters in the Miniature Earthquake Machine segment.

This experiment, based upon a claim by inventor Nikola Tesla that his mechanical oscillator produced an earthquake in 1898, employed a small tunable reciprocating mass driver to shake the bridge at its resonance frequency.

While not structurally significant, the shaking was felt some distance from the driver.

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Category: Fog City - City of Fog, San Francisco Bay

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