Sources: Infrastructure Data Solutions, Regina, Saskatchewan; CP staff
Twenty-five years of sustained funding, plus advanced construction and engineering practices, have led to a steady improvement of the condition of U.S. bridges. Infrastructure Data Solutions’ (IDS) analysis of the Federal Highway Administration’s latest National Bridge Inventory data reveals a 12-point decline in the number of bridges deemed structurally deficient over a quarter century.
From 1992 to 2016, NBI structures carrying such designation dropped from 118,757 to 55,309, or from 21 percent to 9 percent of the inventory. IDS finds the level of structurally deficient bridges trending down in most states, with New York logging the largest reduction, from 9,884 (57 percent of the 1992 state inventory) to 1,885 (11 percent of 2016 inventory). Other significant reductions have been realized in Missouri (27 percent lower), Mississippi (21 percent) and Oklahoma (20 percent). 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). California continues to have the highest total deck area of deficient bridges, followed by Louisiana, New York, Illinois and Pennsylvania. The number of bridges deemed functionally obsolete—another FHWA metric for NBI structures—has dropped from 80,461 to 75,703 from 1992 to 2016.
“Despite overall condition improvements, big challenges lie ahead,” says IDS President Dr. Mahmoud Halfawy, noting how approximately one in five bridges in the U.S. warrants work. “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 over the next 20 to 30 years. To sustain past progress, agencies will need to get aggressive in implementing new efficiencies and introduce innovation in bridge preservation, programming and project delivery.” — IDS, 306/790-1415; www.ids.consulting or www.NBIBenchmarking.com