Highway In The Sky

Bridges are a hot topic when American infrastructure is discussed. A 2005 "report card" issued by the American Society of Civil Engineers reported that, the percentage of the nation's 590,750 bridges rated structurally deficient or functionally obsolete decreased slightly from 28.5 percent to 27.1 percent between 2000 and 2003. That report noted that it would cost $9.4 billion a year for 20 years to eliminate all of the deficiencies on bridges across the U.S., and said that term underinvestment is compounded for the long term by the lack of a federal transportation program.

There are two new bridges, however, that will open to traffic within the next 8 months.

Advanced design presents challenges
For medium length spans (those between 500 feet and 2,800 feet), cable-stayed bridges are becoming the design of choice (see sidebar, Differences between suspension and cable-stayed bridges). Such a bridge is nearing completion in Toledo, Ohio. It will carry heavy, interstate traffic across the Maumee River, to and from industries in Detroit and surrounding areas. An existing drawbridge will remain for local traffic use.