What Is the History of the Drawbridge?

The Tower Bridge in London, England, is a drawbridge.

Drawbridges have evolved over the centuries from castle defenses to convenient ways of allowing large ships to pass through navigable, often urbanized, waterways. The materials used and the mechanization of them has changed over the years as well.

Drawbridge Description

There are several types of drawbridges. Single-leaf bridges open and lift on one side of a waterway. Double-leaf bridges open at the middle and lift on both sides of the waterway. Some bridges lift vertically, much like an elevator or retract in on themselves.

Ancient Drawbridge History

Although there is evidence of drawbridges used by the ancient Egyptians 4,000 years ago, they were not common until the Middle Ages in Europe. They were called bascule bridges, used the one-leaf configuration and spanned Norman and Plantagenet castle moats. Leonardo da Vinci was building and designing many drawbridges by the end of the 15th century.

Modern Drawbridge History

Modern drawbridges were developed in the middle of the 19th century due to the advances in steel production. The durability of steel allowed these bridges to be larger and higher above the water. Many of the drawbridges in the United States were built in the early part of the 20th century. As technology has advanced, hydraulics have begun to replace gears as moving mechanisms.

References

• Made How: How Products Are Made--Drawbridge
• Castles: Castle Drawbridge