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The Evolution of Bridges in the United States

The Evolution of Bridges in the United States 67.1 67.2 67.3 Introduction Early U.S. Bridges The Canal Era Turnpikes • Timber Bridges • Covered Timber Bridges • Iron Bridges 67 67.4 The Railroad Era Trusses • Railroad Trestles • Steel Arch Bridges • Kit Bridges 67.5 The Motor Car Era Steel Truss Bridges • Reinforced Concrete • Concrete Arches • Concrete Girders • Canticrete • Suspension Bridges • Movable Bridges • Floating Bridge 67.6 The Interstate Era Concrete Box Girders • Prestressed Concrete • Composite Steel • A Resurgence of Steel • Steel Girders • Steel Box Girders and Orthotropic Steel Decks . | Root N.F. The Evolution of Bridges in the United States. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 67 The Evolution of Bridges in the United States Norman F. Root California Department of Transportation 67.1 Introduction 67.2 Early U.S. Bridges 67.3 The Canal Era Turnpikes Timber Bridges Covered Timber Bridges Iron Bridges 67.4 The Railroad Era Trusses Railroad Trestles Steel Arch Bridges Kit Bridges 67.5 The Motor Car Era Steel Truss Bridges Reinforced Concrete Concrete Arches Concrete Girders Canticrete Suspension Bridges Movable Bridges Floating Bridge 67.6 The Interstate Era Concrete Box Girders Prestressed Concrete Composite Steel A Resurgence of Steel Steel Girders Steel Box Girders and Orthotropic Steel Decks 67.7 Era of the Signature Bridge Segmental Prestressed Bridges Cable-Stayed Bridges Composites 67.8 Epilogue 2000 by CRC Press LLC 67.1 Introduction American civilization with its bridges is relatively recent compared with the ancient civilizations of Asia Europe and even South America. The Americas are the last continents to have become heavily populated and industrialized. The evolution of bridges in the United States is probably not much different from anywhere else in the world. Civilizations have borrowed their bridging ideas from each other for centuries. Fallen logs across streams served as primitive bridges that led to the concept of girder spans in use today. Suspension spans across deep chasms is a primitive idea used throughout the world. The stone arch introduced by the ancient Romans is a naturally occurring efficient and pleasing structural shape that has been used with various evolving materials. FIGURE 67.1 The aqueduct bridge at La Purísima Mission Santa Barbara County California is an example of a primitive bridge a short-span stone slab. Built in 1813 it is the oldest bridge in California. Courtesy of California Department of Transportation. Bridge practice evolves as user needs traffic and