One year ago today, the Interstate 35W bridge in Minnesota collapsed into the Mississippi River, killing 13 and injuring dozens more and alerting the government and the public of the need to repair deficient U.S. bridges.
A study released this week by the American Association of State Highway and Transportation Officials (AASHTO) reported that nearly 25% of the 600,000 bridges in the U.S. need to be modernized or repaired, with the bill for all renovations topping $140 billion.
The study, entitled “Bridging the Gap: Restoring and Repairing the Nation's Bridges,” said that bridges are built to last about 50 years, but the average bridge in the U.S. today is 43 years old and near the need for replacement to reduce the possibility of another collapse.
“At the anniversary of the August 1, 2007, Minnesota bridge disaster, Americans no doubt will be wondering about the status of the nation’s 590,000 bridges,” the report said. “Carrying hundreds of thousands of commuters and other traffic as well as much of the nation’s commerce, bridges are the fundamental backbone of this country’s economy. At the same time, however, bridges are so common that they melt into the backdrop of everyday life, and their importance in the functioning of our society is often overlooked.”
Many bridges are structurally deficient, functionally obsolete or too narrow for today’s traffic volume, leading to increased congestion. The top 10 highway interchange bottlenecks cause an average of 1.5 million truck hours of delay annually, the report said.
The problem is not necessarily just the age of the bridges but deterioration due to increased volume. According to the report, annual travel on the Interstate Highway System grew 28% between 1995 and 2004, while truck travel—of which 90% travels over state-owned bridges--has nearly doubled in the past 20 years and is expected to double again by 2035.
The number of structurally deficient bridges varies widely by state, according to the Reason Foundation’s 17th Annual Report on the Performance of State Highway Systems. About 24.1% of the597,598 bridges in the current National Bridge Inventory were deemed deficient, ranging from Nevada (3.9% deficient) to Rhode Island (53.4% deficient).
However, increased construction costs have made it significantly more difficult to start new repair projects, as the costs of steel, asphalt, concrete, and earthwork have risen more than 50% in the past four years. In addition, 30 months of unprecedented construction inflation has caused state officials to delay important bridge replacement projects, the AASHTO report said.
“The National Surface Transportation Policy and Revenue Study Commission estimates that the United States should be investing about $225 billion annually for the next 50 years on all modes of transportation,” the AASHTO report stated. “Today, the U.S. is spending about 40% of that.”
According to the U.S. Department of Transportation’s 2006 Condition and Performance Report (C&P), an additional annual investment of over $12.4 billion is necessary to improve bridge conditions to a level that would help relieve congestions and reduce accidents. However, signs point to future funding actually going down, not up.
“The Highway Trust Fund, which is the primary funding source for all federal aid for highways and bridges, is on the verge of massive shortfalls,” the AASHTO report continued. “Without new revenue, these shortfalls in 2010 could force a 50% reduction in funding below today’s already inadequate investment levels.”
The federal law that authorizes funding for the nation’s transportation system is set to expire in September 2009. Congress, the next Administration and individual states must focus on setting funding for the next decade of transportation needs, AASHTO said.
AASHTO calls for additional investment, increased research and innovation, implementing long-term management systems for the entire inventory of bridges, increasing public awareness, and raising funds—primarily through tolling and increasing tax revenues—to raise the necessary capital.