A perfect balance between compression and tension has allowed for man to travel across bodies of water. While some early civilizations felled trees to create rustic wooden bridges over rivers, Roman engineers worked with stone to create arches and aqueducts. The Chinese were utilizing bamboo cables as early as 300 A.D. to carry foot traffic 1,000 feet across the Min River.
The Industrial Revolution kicked engineering to new heights with the Brooklyn Bridge being a groundbreaking feat in 1883 when it became the world’s longest bridge. Then the Scottish got in the game with the Firth of Forth Bridge. The Golden Gate Bridge again put the United States at the forefront of bridge engineering in 1937.
Though it would appear that bridge construction has not changed for many years, according to City College of New York Civil Engineering Professor Anil Agrawal, that perception is actually quite false. While to the untrained eye there is nothing dramatic going on with bridge engineering and construction, there are sophisticated advancements that are “making modern bridges bigger, safer, and longer-lived.”
Kelly Sills, who has owned a bridge and road construction company in Louisiana and Florida for years and has spent his entire career involved in bridge construction, says that the path of advancements in bridge engineering mimic those of any other industry.
“You are always going to find people who push for advancements, people who accept advancements and others who resist any kind of change,” Sills said. “Still, there is evidence all over the world that bridges are becoming longer, stronger, better and safer – with built-in components for monitoring,” Kelly Sills added.
Safety has been a major focus for civil engineers lately. They have been focused on “making bridges more resilient to fire, earthquakes, and high winds. They’re also exploring how technology can help them monitor new bridges and maintain those already in place,” according to the How Stuff Works article.
As an alternative to costly and sometimes unreliable manual inspection of bridges, sensors are now being incorporated into a bulk of new bridges in order to collect data on structural behavior and condition.
Now employed on the Jindo Bridge in South Korea is the first full-scale roll out of the wireless smart sensor technology designed to “continuously–and reliably–monitor structural health.”
A collaborative effort between the University of Illinois at Urbana-Champaign, KAIST in Korea and the University of Tokyo, the dense wireless sensor network is the largest of its kind thus far in civil engineering/infrastructure.
It is a way to monitor safety, changes, and transmit complex information about structural integrity efficiently and cheaply.
“It is a bridge of the future,” said Sills. “This technology can change the entire industry and make mitigation efforts more timely and increase safety for the vast number of people who cross bridges daily all around the world.”
Just as safety measures are more high tech, the bridges themselves are becoming far more complex and capable of traversing vast distances.
After nine years of planning, the ??Hangzhou Bridge in China now stretches an astonishing 22 miles across the Qiantang River at the Yangtze River Delta on the East China Sea and carries six lanes of traffic in both directions. The lifespan of this bridge is expected to be around 100 years, or double that of most other bridges.
According to the Infrastructure Report Card the United States has over 617,000 bridges, “Currently, 42% of all bridges are at least 50 years old, and 46,154, or 7.5% of the nation’s bridges, are considered structurally deficient, meaning they are in “poor” condition. Unfortunately, 178 million trips are taken across these structurally deficient bridges every day.”
Increasing the longevity and safety of bridges when the U.S. is facing a major issue in aged infrastructure will be essential to create safe means of transportation for the future, said Sills.
Fortunately, novel technologies are generating more creative options like new types of concrete and altered bridge shapes to decrease wind resistance. Also, these advancements “are being studied in labs around the world.” It is simply a matter of bringing civil engineering standards as well as building codes into the new era, according to MIT Technology Review.
