Most of the bridges in Southern California were built in the 1950s and 1960s, and they are nearing the end of their life spans.
"Every facility, every building, every bridge has a useful life, and the design life is usually 50 years, and after that it becomes obsolete because new codes, strengthening and just the wear and tear of the structure needs repairs," said Henry Koffman, a professor of civil engineering at USC.
According to the American Society of Civil Engineers, California has 2,978 structurally deficient bridges. That means they require significant maintenance, and there could be deterioration or damage.
But officials stress they are not on the brink of collapse.
"A common misperception is that age dictates the structural integrity of a bridge, and that's not the case. Older bridges might be perfectly safe, so people don't have to worry that if they are driving over an older bridge, that they would have to be worried about that, that's not the case," said Kelly Markham with Caltrans.
Before Thursday's collapse in Washington state, there have been several tragic bridge accidents, including one in Minneapolis in 2007 that killed 13 people. After that, a number of states made immediate repairs.
"Bridges in California are inspected every two years and they are safe," said Markham.
But experts say thousands of bridges all over the country are simply old and not properly and maintained. It will cost billions to update the country's infrastructure.
"We're going to see more and more of that, unless the public and the politicians become aware that what we need is funds to maintain our existing facilities," said Koffman.
According to the report by Transportation for America, at the current rate that bridges are being repaired, by 2030, as many as 20,000 bridges nationwide could be 50 years or older.
