Big Apple's bridge problems
FEDERAL Highway Administration data on structurally deficient bridges and the government's $50 billion estimate to bring them all up to standard should make it obvious that the problems of New York City's Williamsburg Bridge, which closed recently, are anything but unique to that city. During the past 15 years, I've participated in many investigations into various kinds of failures, so I also know that bridges aren't the only structures in danger.
America's construction industry is courting disaster by spending millions of dollars on repairs and litigation instead of putting the money into strengthening the industry's base of knowledge, and by that I mean research.
In 1981, at the Orlando Civic Center, a large jumbo section in a truss tension chord cracked during construction.
In 1987, the Seattle Convention Center experienced difficulties with large jumbo sections in trusses.
In 1985, at Virginia's Wolf Trap performing arts center, inadequate welds contributed to the fracture of a girder.
These and other failures can be traced to inadequate knowledge. Without this base of knowledge, you cannot design or build structures properly, nor can you, as with the Williamsburg Bridge, adequately detect changing service conditions.
For example, there is work being done to develop remote corrosion sensors that would be installed in crevices and just under the paint on a bridge, where corrosion usually originates. These sensors, monitored by computers, would make it feasible for bridge inspectors to monitor the condition of many bridges.
Also, large-scale structural testing before a bridge or building is put into service can be done. In the past, new materials and designs were tested with small structural components. The results then were extrapolated to arrive at design codes for larger structural members. Unfortunately, this doesn't always work.
Without the necessary engineering data, construction companies not only spend time and money on costly repairs and expensive and damaging litigation, they also pay for increased insurance rates and wasteful delays in projects.
While United States structures-related industries as a whole employ about 5 million people and account for more than $300 billion annually in the domestic market, or about 7.5 percent of the gross national product, their total annual spending for research and development are four-tenths of 1 percent of total sales. Some of the major Japanese construction companies invest more on research than our nation's total private sector. As a result, foreign competition is grabbing market share here and abroad, but that's another problem.
There are many more Williamsburg Bridges in America. Our nation's decaying infrastructure needs more than a band-aid approach. Research into building better, more reliable structures and ways to monitor them once built will give us the long-term answers we need.
John W. Fisher, professor of civil engineering at Lehigh University and director of the National Science Foundation Advanced Technology for Large Structural Systems engineering research center there, is a member of the New York City Transportation Department's advisory committee that is studying the future of the Williamsburg Bridge.