Wednesday, August 17, 2016

What “Structurally Deficient” and “Functionally Obsolete” REALLY Mean

Bridge number 53-0062, the Manhattan Beach Undercrossing on PCH, built in 1930.
From time to time, a report of some kind or a news story will declare that X percentage of bridges in California are structurally deficient or functionally obsolete. And if hearing that bridges you drive over may be structurally deficient or functionally obsolete gives you pause, you’re not alone. Admittedly, these loaded terms are terrific triggers for bridge anxiety, but rest assured that the reality is far less scary.

First, let’s be clear: No Caltrans bridge has ever collapsed due to neglect. Ever. Which isn’t to say that bridges don’t collapse. They do. They’re consumed by floods, brought down by fire, leveled by earthquakes, and hit by trucks, but in California, bridges do NOT collapse because they're not maintained. In large part, that flawless record is made possible by a special unit created by the department in 1927 to ensure the safety and reliability of the state’s bridge inventory. 

Sr. Bridge Engineer Bing Wu at work.
Two hundred specially trained engineers, technicians and support staff in Caltrans Structure Maintenance & Investigations (SM&I) are responsible for inspections on over 12,000 state highway bridges and approximately 12,200 bridges owned by local government agencies. Every bridge undergoes regularly scheduled routine inspections performed by licensed engineers with an expertise in bridges. Inspections have one purpose: to ensure the safety and reliability of every bridge open to traffic. 

If, during the course of an inspection, inspectors find any issue that could compromise the bridge’s structural integrity, they have the power to do whatever it takes to protect public safety, including closing the bridge or posting the structure for weight limitations until repairs are made.

Now, about those scary terms. Some of California’s older bridges are in good shape but functionally obsolete. This term, which is a federal designation, tells us more about the age of a bridge than its structural integrity. Functionally obsolete simply means that the bridge was built using different standards than are used today—like bridge number 53-0062 in the photo above. For example, a functionally obsolete bridge may have no shoulders and narrow lanes. Would we build a bridge like this today? No. Is it unsafe? No. 

Some of our bridges are also structurally deficient. Like the label functionally obsolete, structurally deficient doesn’t mean a bridge is unsafe. Rather, it indicates that a bridge is in need of maintenance, such as filling minor cracks or repainting. These are conditions that would be noted during a bridge inspection and later fixed. In the meantime, the bridge can be safely used by the motoring public.

So the next time you hear or read that a bridge is functionally obsolete or structurally deficient, remember: the bridge is NOT unsafe. Typically, it means that it’s an older bridge or has some minor maintenance issues that can be handled fairly easily and inexpensively. If the bridge is open, it’s safe. Traverse California's bridges with confidence!