![]() Concrete is now also used to build modern arch bridges.Ī bridge’s load is the weight of the bridge itself (called the dead load), combined with the weight of whatever it carries (the live load). This bridge design dates back more than 3,000 years. The Romans built more than 1,000 stone arch bridges, some of which still survive, such as the Pont-Saint-Martin bridge in Italy’s Aosta Valley (built in the first century BCE). Correct engineering and bridge construction can strike the perfect balance to keep a bridge standing. The world’s longest bridge, the $8.5 billion Danyang-Kunshan Grand Bridge in China, carries a high-speed railway more than 100 miles.īridges work by balancing the forces of physics through a superstructure (girders, trusses, etc.), which bears the bridge deck and its load, and a substructure ( pillars, abutments, piers, and footings), which grounds the load into the earth.Ī bridge needs to resist movement so it can provide a stable surface to cross a divide. Now it’s common to see massive, intricate modern bridges that span shockingly long distances. Innovation has resulted in different structures and types of materials used to span waterways and canyons. 7 Different Types of Bridgesīeginning with the first tree trunk laid across a creek bed, humans have created increasingly sophisticated bridge designs through the ages. As long as it gets us across a span that would otherwise be difficult (or even impossible) to cross, a bridge serves its singular purpose. Whether they’re simple footbridges, functional toll bridges, or complicated drawbridges, they all serve an essential function.īridges can be the simplest structures or huge, stunning works of art - or anything in between. They’re gateways to discovery - and the way many of us get to work each day. Bridges, from Sydney Harbor to the Tower Bridge across the Thames to the Golden Gate, connect us and bind us together.
0 Comments
Leave a Reply. |