US bridges astride abyss of poor repair, few funds. OVER TROUBLED WATER

``The nation's bridge problem remains serious.'' That's what the secretary of transportation's eighth annual report on the ``highway bridge replacement and rehabilitation program'' stated last November. This conclusion was reinforced this week when the National Transportation Safety Board warned that about 43,000 bridges nationwide are overdue for inspection. Many, the board said, may suffer from the same problems that caused the collapse of an Interstate span over the Schoharie Creek near Albany, N.Y., last year, in which 10 motorists were killed.

The board cited inadequate maintenance as the major ``probable cause'' of that tragedy. It urgently recommended all states to inspect underwater bridge foundations as soon as possible for signs of soil erosion or scouring beneath these foundations.

``It needs to be done and done rapidly,'' Bernard S. Loeb, deputy director of the agency's Bureau of Accident Investigations, was quoted as saying. ``This is the time now when you've got snow melting and heavy rains.''

Poor maintenance also shut down the Williamsburg Bridge between Manhattan and Brooklyn earlier this month. An inspection disclosed some seriously rusted beams, and city officials closed the bridge to vehicle and subway traffic. Some 240,000 daily commuters had to find alternative routes to get on and off Manhattan.

Democratic candidate Jesse Jackson, while campaigning in the New York primary, led a parade of followers across the bridge. His point was that some defense money should be diverted to rebuilding bridges.

On average, some 150 bridges across the United States fall down every year, usually not involving deaths or injuries. The latest annual bridge report found that 131,562 of the nation's 575,607 inventoried bridges are ``structurally deficient.'' That term applies to bridges that (1) have been restricted to light vehicles only, (2) are closed, or (3) require immediate rehabilitation to remain open.

Some 111,905 bridges are posted with load limits, and 4,125 have been closed to traffic.

In 1986, the total estimated cost of the 5,925 bridge projects helped by federal money was $3.6 billion. State and local governments spent between $500 million and $1 billion on other bridges where no federal money was involved. The federal government is spending about $1.63 billion each year.

The annual report estimates it would take $51.4 billion to replace or rehabilitate all deficient bridges. That number has stayed relatively stable for the past several years.

The report further states that this near-balance between the rate of deterioration of bridges and their rate of repair should not change significantly over the next three to five years at current funding levels. But beyond that time frame, bridge spending needs should increase. That's because so many bridges built during the peak of Interstate highway construction in the 1950s and 1960s are reaching an age when more repairs will be needed.

Dr. Loeb of the safety board estimated that 10,000 to 30,000 bridges of the Schoharie Creek type were constructed between the 1940s and the '60s and may need inspection and maintenance. The safety board says four bridges of such design have collapsed in the US since the April 5, 1987, accident.

William Reulein, branch chief of the office of policy planning at the Federal Highway Administration, says there is enough bridge money available to deal with critical situations. But the problem is identifying bridges that are in critical need of repair or replacement.

The FHA requires that all bridges be inspected every two years. The safety board has urged the Transportation Department to withhold federal highway funds from states that do not comply with national bridge inspection standards. It is a right that the officials already have, but rarely use.

The board also suggested the inspector general of the department ensure it is properly overseeing state bridge inspection programs.

The board further called on the American Association of State Highway Transportation Offices to update technical bridge inspection manuals to better account for the effects of scouring.