An analysis conducted by Infrastructure Data Solutions (IDS) of national bridge inventory (NBI) data collected by the U.S. Federal Highway Administration (FHWA) indicates that while there’s been a “remarkable decline” of structurally deficient roadway bridges over the last quarter century, many are beginning to approach the end of their lifespan.
That means a “big wave” of replacement demand should begin to crest within the next several decades, noted Mahmoud Halfawy, president of IDS, in a statement.
"Based on our analysis, the average age of bridges nationwide is 36 years, and given that the average design life of most existing bridges is 50 years, a big wave of structurally deficient bridges is expected to spike over the next 20 to 30 years," he said.
Halfawy added that the “total deck area” of bridges built in the 1960s and 1970s now represents almost 35% of the total deck area of the nation’s current roadway bridge inventory.
“Many of these bridges will soon be due for major rehabilitation or replacement,” he pointed out. “With current levels of funding available to agencies, it is extremely challenging to keep up with the expected needs, Halfawy stressed.
He noted that as of 2016, according to the data analyzed, some one in 5 bridges in the U.S. is in need of some improvement. "To sustain past progress, agencies will need to get aggressive in implementing new efficiencies and introduce innovation in bridge preservation, programming, and project delivery," Halfawy added.
That being said, IDS’s report also credited “sustained funding and improved practices” over the past 25 years for beefing up the conditions of U.S. roadway bridges overall, according to its analysis:
- FHWA data indicates the number of “structurally deficient” bridges declined to 55,309 or 9% of nationwide inventory in 2016, compared to 118,757 or 21% of the inventory back in 1992, IDS found.
- However, the number of functionally obsolete bridges nationwide dropped only slightly over the past 25 years; from 80,461 in 1992 to 75,703 in 2016, the firm said.
- Yet between 2015 and 2016, the number of deficient bridges dropped by 2,735, IDS pointed out.
- New York has seen the largest reduction in deficient roadway bridge structures, IDS said, from 9,884 or 57% of the state inventory in 1992 to just 1,885 or 11% last year. Other significant reductions were in Missouri (27%), Mississippi (21%), and Oklahoma (20%).
- The five states with the highest number of structurally deficient bridges in 2016 are Iowa (4,931), Pennsylvania (4,410), Oklahoma (3,414), Missouri (3,147), and Nebraska (2,326), according to the firm’s analysis
- California continues to have the highest total deck area of deficient bridges, followed by Louisiana, New York, Illinois, and Pennsylvania, IDS said.
