A tire-size hole broke through a busy East Baltimore viaduct yesterday morning, causing city officials to close the bridge temporarily and to halt truck traffic on it for at least two years.
The circular cavity -- 2 feet wide and at least 10 inches deep -- appeared in one of the eastbound lanes of the O'Donnell Street bridge at Haven Street around 7 a.m. Debris rained down on freight tracks below the 39-year-old structure.
No accidents or injuries were reported, police said.
City public works engineers blamed the damage to the bridge's deck on the bridge's age and the effects of harsh cold, ice, snow and road salt during the severe winter.
When the bridge last was inspected two years ago, city consultants recommended extensive renovations, including replacing its concrete deck. In a Dec. 9, 1992, letter, Geoffrey V. Kolberg, an engineer with Rummel, Klepper & Kahl, the firm hired to inspect the bridge, described the problems as "severe" and requiring "immediate attention."
A 1990 inspection of the four-lane bridge also recommended that the decks of both spans be replaced.
Despite the criticisms, the city has done little more than patch periodic pot holes in the surface. City public works officials said they have been checking on the deck's condition at least once a month and have planned more permanent repairs.
Dave L. Montgomery, head of the city's Bureau of Transportation, said the bridge's structural problems are not so severe that they pose a hazard to car traffic. He said a complete rehabilitation of the bridge -- including a new deck -- already was set to begin next year.
"This isn't something we just tripped over," Mr. Montgomery said. "We've looked at it in the past, but maybe we didn't see the magnitude that we should have."
Truck traffic along the bridge will not resume until the overhaul is completed in 1997 at a cost of $6 million to $10 million, said Vanessa Pyatt, a public works spokeswoman. Big rigs headed down O'Donnell are being detoured around the site through Boston and Haven streets.
Meanwhile, the two westbound lanes have been converted to an east-west thoroughfare for cars until city work crews patch the hole this week.
"We will make temporary repairs until major rehabilitation can begin," Ms. Pyatt said. "Until then, the bridge is sound. We closed the lane for safety reasons."
About 20,000 cars and trucks cross the bridge daily, she said.
The railroad tracks underneath the bridge are owned and operated by Conrail, Inc.
City inspection records show that the structure has deteriorated because of rust, cracks and other damage since 1980.
Ms. Pyatt said that public works maintenance records state that about 50 potholes were repaired on the bridge last year after drivers complained
The O'Donnell viaduct was constructed in 1955 as a steel and multi-beam structure. That steel and concrete composition has proven vulnerable to erosion by salt and harsh winter weather, specialists say, because the water and salt leak into the concrete and rust the steel skeleton.