The July 19 collapse of an Interstate 10 bridge in Riverside County due to heavy rains is prompting questions among experts about weaknesses in transportation infrastructure and its capacity to withstand increasingly extreme weather events.
More than a quarter of the 25,000 bridges in California were deemed either “structurally deficient” or “functionally obsolete” in the 2014 U.S. Department of Transportation’s state-by-state report on deficient state and federal highway bridges. The collapse of one — as illustrated by the failure on I-10, the main route between Los Angeles and Phoenix — can cause major disruption.
USC experts weigh in:
Impact on commerce, trade
“Forty percent of the goods and services that we consume in this country come through the port of Los Angeles-Long Beach distribution and transportation network. The I-10 freeway is actually one route that carries supplies to the rest of the country. The 50-mile stretch of interstate that has been shut down will impact the flow of goods to Arizona, New Mexico and other states. Billions of dollars in trade can be impacted.
“I think the lack of infrastructure investments have been a major concern of ours for a long time. The bridge collapse at Desert Center is just an example of much-needed work on infrastructure in our country. This could be a wakeup call to assure that we have a strong commitment to enforcement and infrastructure that ensures our supply chain is robust.”
assistant professor and director of the USC Marshall Center for Global Supply Chain Management
Learning from failure
“We need to look at all the root causes of this accident. A major bridge collapse, like any other complex systems failure, has multiple and complex root causes. We need to look at the ‘total system’ and all the contributing factors in this context: from design, material quality and integrity, adequacy of engineering codes and standards, construction, workmanship, structural health monitoring, and traffic load, cumulative stress and fatigue, initiating events, regulatory and oversight mechanisms, and all the way to the safety culture of agencies that are responsible for maintenance regimens – both preventive and corrective maintenance.”
professor, USC Viterbi School of Engineering
Design and construction considerations
“The bridge was never designed to withstand a huge flood. Engineers have certain design criteria. Should we design structures to withstand a 10.0 earthquake or an 8.o earthquake – which we do?
“This was a very unusual heavy storm and flooding. We rate storms in terms of probability of occurrence. For instance, a 100-year storm is extremely heavy and is only expected to occur once every 100 years. A 1-year storm is expected to occur every year and is light. Where do you draw the line to design?”
engineering professor and director of the USC Viterbi Construction Engineering and Management Program