On Aug. 1, 2007, one of the worst civil engineering disasters in U.S. history occurred when the Mississippi River Bridge in Minneapolis, Minnesota, collapsed during the evening rush hour. The catastrophic equipment failure plunged hundreds of cars into the river below, killing 13 people and injuring 145. The accident served as a wake up call to the decay of America's aging infrastructure. Now more than eight years later, cutting-edge technology is part of the solution to this challenge.
In the rebuilding of the I-35 bridge, engineers took steps to ensure a tragedy of that scale was not repeated. As part of the new bridge's design, engineers installed 323 specialized sensors in the structure's support columns and interior, according to Engineering News-Record. These sensors detected minute changes in load and vibration and were able to unveil invisible structural problems before they lead to failure. This is one of the earliest examples of what's now known as intelligent infrastructure. These new technologies capture and instantly relay complex data concerning structural integrity, as well as traffic patterns, weather conditions and much more. Innovations in intelligent infrastructure represent the next generation of America's now dated transportation system.
"More states are rushing to gather data about their transit infrastructure."
According to a report by ENR, "the stars of [intelligent infrastructure] are aligning," thanks to greater interest and funding for these ambitious projects.
Besides the aforementioned I-35 bridge, few construction project managers embraced the technologies underpinning intelligent infrastructure. With the rise of the big data movement and a greater reliance and ability to work with complex sensory information, things may start changing in a big way. A recent authorization for federal highway funding called MAP-21 stipulates the adherence to performance targets based on hard data. With this impetus, more state transportation departments are rushing to collect a broad degree of data about their highways and transit infrastructure through the use of new technology.
In its most basic form, intelligent infrastructure includes the use of cameras and traffic sensors to monitor flows and detect bottlenecks. These cameras and sensors upload the data to a cloud-based software that can interpret and manage the massive amount of data, with the ability to change speed limits with the use of programmable signage, for example.
MAP-21 has lead to the implementation of more sensor technology similar to what is seen in the new Minneapolis bridge. Only recently conceptual designs until recently, these new sensors are fitted to piles, girders or decks on bridges or overpasses and detect unseen forces acting on the structure[revise for clarity. is this an interjection? it's unclear what is being said here]. The multitude of data these sensors capture are beamed to the cloud for processing, but exactly what should be done with it remains a mystery to many engineers, and a very expensive one. Even with the funding incentive, some designers are reluctant to install such technology without seeing immediate savings.
New applications, more potential
One company has become known for implementing similar technology used for short-term, construction safety systems monitoring that could provide a real ROI benefit. Smart Structures, Inc. of West Palm Beach, Florida, has designed an innovative set of sensors that are molded into the concrete and metal of bridge components themselves. The devices are inside of the concrete piles and steel supports from the beginning, and can be activated during the building process to assess loads and driving accuracy.
Using accelerometers and gauges for tilt and strain, these sensors wirelessly send information to equipment crews to detect stress or possible damage as they are driven into the ground. This could save valuable time correcting any problems that may occur, not to mention catch a crack before it becomes a collapse. While more than 3,000 of these devices have been implemented in projects in Florida, the Carolinas, Virginia and Maryland, almost none of their users continues to monitor the data after the project's completion. Founding team member and engineering manager Kurt Hecht believes it's only a matter of time before this changes.
"It will become a reality," Hecht told ENR. "It's a question of when. Federal highway officials need to step up and say, 'This is in the best interest of everybody.' "