Bridges have been around for many centuries, as long as humans have needed to get from one side of a body of water or valley to another. These architectural structures date back to ancient times, and some very old bridges are still in use today. The oldest bridge that is still passable today spans the River Meles in Turkey, and this bridge is estimated to have been built around 850 B.C.E. The oldest bridge that is no longer usable is the Arkadiko Bridge, located in Greece. This bridge dates back to 1300 B.C.E.
Facts About Bridges
Bridges make traveling easier because they enable travel over water, valleys, and canyons. Although bridges may seem relatively simple, they involve complex engineering. There are many different types of bridges made from a wide variety of materials, but every bridge includes a foundation, substructure, and superstructure. Designing a bridge involves consideration of the weight it will hold, the weather it will endure, the terrain around the bridge, the materials to be used, and the budget.
- Bridge Facts: The type of bridge used to cross a span depends on the terrain.
- Bridge Structural Elements: Parts That Go Into Building a Bridge
- Component Parts of a Bridge
Types of Bridges
The type of bridge needed for a particular place depends on the climate, how the bridge will be used, the weight it needs to hold, and other factors. Arch bridges are very common, and they date back to ancient times in Greece and Rome. Suspension bridges are used to span large obstacles, but they can’t hold as much weight as other types of bridges. Suspension cables connect vertical pillars to hold up the bridge deck with tension. Beam bridges are inexpensive to build, and they are supported by abutments at each end and possibly in the center sections. Cantilever bridges have vertical pillars that support the horizontal deck from both above and below. Tied arch or bowstring bridges are a combination of suspension and arch bridges that use tension in vertical cables and compression in the arch to support the bridge load. Steel truss bridges are economical to build, and they have diagonal truss supports that use compression to make the bridge stable.
- Types of Bridges: Bridges vary from very simple construction to very complex structures.
- Seven Types of Bridges Every Engineer Should Know About: The best bridge for a location depends on factors such as the length of the span, weight of traffic, and budget.
- Building Bridges: The Basics
- Types of Bridges
How Are Bridges Constructed?
Bridge construction methods depend in part on the type of bridge and the terrain around the bridge. Current technology involves the use of heavy machinery, new building methods, and stronger materials. Bridge engineering requires extensive planning, site testing to examine the soil strength and land layout, and precise physics to design and construct the required bridge components. Bridge construction starts with building the foundation and support piers. Caissons are large cylinders made of concrete, metal, or wood that are sunk into the ground and filled with concrete. Some construction may be completed off-site, and then the components are brought to the construction site to be joined together.
Covered Bridges and Historic Bridges
Covered bridges are usually small truss bridges, and they are located in rural areas, spanning small rivers or streams. These historic bridges are found in many parts of the United States, and they are often surrounded by beautiful scenery. Covered bridges and their enclosures are built to withstand the elements, so they often last longer than some other types of bridges. Covered bridges may be built for trains, cars, or foot traffic.
- The History of Covered Bridges in America: One of the first known covered bridges in America was built in Philadelphia.
- Ohio’s Vanishing Covered Bridges: Covered bridges have been discovered dating back to 780 B.C.E., but America’s covered bridges were primarily built in the 1800s.
- Why Are Covered Bridges Covered?
- Covered Bridge Trivia
Bridge Failures and Disasters
Bridges don’t usually fail, but when they do, massive disasters are typically the result. Common reasons for bridge failures are metal fatigue and weakness. However, bridges can also fail because of catastrophic collisions and natural disasters. After a bridge disaster, experts study the scene and determine why the failure occurred. Then, engineers can design a new bridge that will avoid the issues that caused the failure. Load testing enables engineers to design stronger bridges and to place load limits on bridges. Ongoing bridge maintenance is crucial to ensure that components remain in good repair.
- What Can We Learn From History’s Biggest Bridge Disasters? Most bridge disasters are caused by collisions, fires, or extreme weather.
- Seven of History’s Most Devastating Bridge Collapses
Famous and Impressive Bridges of the World
A number of impressive bridges have become famous for their architecture and engineering. The Alcantara Bridge in Spain dates back to around 105 C.E., when it was built by order of Roman Emperor Trajan. The longest suspension bridge is the Akashi-Kaikyo Bridge in Japan. This bridge is 6,532 feet long and spans the Akashi Strait. The Tower Bridge in London spans the River Thames and features two towers connected by horizontal walkways. The Golden Gate Bridge is a famous suspension bridge that connects San Francisco with Marin County, California. This bright orange bridge was completed in 1937.
- 15 Most Famous Bridges in the World: Famous bridges around the world have become iconic landmarks.
- Top Ten Most Famous Bridges in the USA: The Brooklyn Bridge, the Golden Gate Bridge, and the Sunshine Skyway Bridge are three of the most famous bridges in America.
- 55 Most Famous Bridges in the World