After the Loma Prieta earthquake in 1989, almost all of the Bay Area's toll bridges underwent major upgrades - the Bay Bridge is the last of those projects. Yet even with the focus on retrofitting, there are still 40 Bay Area bridges that rate lower than the one that collapsed in Minneapolis last week. How do we know which bridges are safe?
You may listen to the "Science of Bridge Safety" Radio report online, as well as find additional links and resources.
Amy Standen is a Reporter for QUEST and Radio News at KQED-FM.