Kolberg said the bridge undergoes an annual inspection even though the federal government requires such assessments only every two years.
However, he said the corrosion found in the most recent inspection is not visible and was identified only because ultrasound and radar were used this time. The authority's inability to detect the problem by visual examination could force it to rethink its inspection protocols, he said.
Repair work will take place on the areas of the bridge near the two shores, where concrete barriers form the walls. The soaring suspension section over the middle of the bay will not be affected.
Newer span probably OK
The westbound span is designed in a different manner, relying on steel rather than concrete, and does not require similar repairs, Kolberg said.
The first phase of the emergency repairs will require the closing of the right lane of the eastbound span. Some subsequent phases will close the left-hand lane as traffic shifts to the right lane.
The work taking place over the next 10 weeks is expected to provide only a temporary fix. Kolberg said engineers are still studying ways to permanently strengthen the barriers. They are not expected to be replaced.
It was unclear yesterday whether the design of the Bay Bridge barriers is common around the country. The current barriers were installed in the 1980s.
Lindsay Reilly, an authority spokeswoman, said the agency is reviewing the design of all its bridges to look for similar barriers. She said that if any are found to be similar, they will be inspected using the same advanced techniques used on the Bay Bridge.
Kellie Boulware, a spokeswoman for the State Highway Administration, said that agency is not aware of any barriers with a similar design on the roads it manages.
Nancy Singer, a spokeswoman for the Federal Highway Administration, said yesterday that her agency just learned of the problem.
"We await further detail to assist the Maryland Department of Transportation in moving forward and to reach out to other states," she said.
The National Transportation Safety Board was also notified of the safety finding. Spokesman Keith Holloway said that for now the agency regards the crash as an isolated incident but would issue an alert if the barriers seem to pose a national problem.
Tony Kane, engineering division head of the American Association of State Highway and Transportation Officials, said he doubts the finding will lead to a national alert.
"That type of crash was kind of unique," he said. "It was a horrible event but probably very, very random."
Authority officials urged travelers to call 1-877-BAYSPAN (1-877-229-7726) for information on bridge conditions.
Baltimore Sun reporter Rona Marech contributed to this article.
