Building the Golden Gate Bridge

The Golden Gate Bridge took a little more than four years to build. Five steel factories made the steel used to construct the bridge. Three factories in Pennsylvania, one in Maryland, and one in New Jersey filled rail cars full of steel beams, wire, and parts. The rail cars did not travel over land to get to the West coast. Instead, they were loaded onto ships. The ships sailed through the Panama Canal and up the West coast.

Steel is a very strong kind of metal. Steel is made mainly from iron and a small amount of carbon. Sometimes there are small quantities of other metals in steel. To make steel, iron is extracted from iron ore in a blast furnace. As you can probably guess, it gets a little hot in there! Iron ore and other materials are heated in the furnace. Everything melts, and then oxygen is injected into the liquid. The oxygen causes a chemical change in the melted metal, and impurities are removed. The impurities, called “slag,” are poured into one container. Steel is poured into another container.

The two main towers of the Golden Gate Bridge contain more than 44,000 tons of steel. Two main cables provide support for the bridge. Each cable runs from one end of the bridge to the other and passes over the towers. About 80,000 miles of wire were used to make the two cables. The final length of each main cable is 7,650 feet, or a little less than a mile and a half.

The building of the bridge was completed in 1937. It was such an accomplishment that the chief engineer, Joseph P. Strauss, wrote a poem about the bridge. The poem is titled “The Mighty Task is Done.” The poem celebrates the accomplishment of the people who built the bridge. It also mentions the bridge's lights, its piers, and, of course, its steel!

Vocabulary

chemical change:: A change in matter in which one or more new kinds of matter form.
impurity:: A substance that, when present, makes another substance not pure or clean.
inject:: To bring or put in.

Sources:

Golden Gate Bridge Facts: http://goldengatebridge.org/research/facts.php#steel
Steel - U.S. Environmental Protection Agency: http://www.epa.gov/msw/steel.htm
American Iron and Steel Institute | Steel Glossary: http://www.steel.org/Content/NavigationMenu/LearningCenter/SteelGlossary/Steel_Glossary.htm