TAMPA - As commuters maneuvered around the collapsed portion of the Lee Roy Selmon Crosstown Expressway project Wednesday, expressway officials looked on the bright side.
New ground-level traffic lanes will open at 6 a.m. Monday and offer two lanes in each direction, easing the traffic snarl. And expressway officials and roadbuilders said the collapse, which occurred Tuesday morning when a sinkhole partially swallowed a pier, has as much chance of happening again "as someone getting hit by a meteor."
"The bridge performed as it was supposed to. It is strong and robust," said Linda Figg, owner of Figg Engineering Group Inc., the design engineer on the project. "It moved as a unit in one piece and stayed together."
Pat McCue, executive director of the Tampa-Hillsborough Expressway Authority, said the bridge design contained the damage when one of the bridge supports sank 20 feet into the ground and two sections of the roadway resting on top collapsed in a V. Two workers were slightly injured.
"It stayed in the median, it didn't come apart, it didn't explode," McCue said at a news conference. "Another kind of bridge might have rolled into the adjacent lanes, into traffic, thrown off chunks of concrete into vehicles, and that would have been a disaster."
Expressway Authority engineers worked through Tuesday night to design new lanes around the damage near N 50th Street so that traffic, already weaving around construction barriers, could return to two lanes in each direction next week. The expressway carries about 85,000 cars a day.
Figg said it would take about 10 weeks to tear down the three ruined sections of the elevated expressway, including one to the east that remained in place but was damaged. Each section is 142 feet long.
Before that work begins, a support will be built under Span 95, the damaged one just to the east of the collapse. Another support structure will be built under Span 96, one of the two collapsed segments of road.
With those supports in place, workers will then dismantle the structure one span at a time. Once that work is done, tests can begin to determine exactly what happened under the sunken pier and how to fix the problem. That pier also will be removed and replaced.
None of the other 60 piers that are in place have shown any signs of problems, McCue said.
The pier was supporting 735 tons of weight when it sank, said Perrydawn Brown, spokeswoman for the expressway authority. Figg said that is nearly four times the weight the pier would have to hold if the road had three full lanes of bumper-to-bumper traffic with cars stacked six high.
Both Figg and McCue said the $120-million elevated road project is ahead of schedule and that the repairs would not postpone next summer's scheduled opening.
When completed, the new three-lane road will operate exclusively for commuters who use the SunPass toll collection system. The reversible-lane road will serve traffic westbound from the Brandon area to Tampa in the morning and eastbound at night. It will be an express route with no ramps to intermediate destinations.
The expressway authority did not make available the geotechnical contractors who did preconstruction tests to check soil stability around the piers. They said the reports those tests generated would be available today.
The field and laboratory testing was done by Williams Earth Sciences of Largo. When contacted Tuesday for general sinkhole information, Craig Ruda, the company's vice president for field operations, had said Williams was not involved in the Crosstown project.
Williams did similar soil testing work for the newest span of the Gandy Bridge and the Suncoast Parkway.
It will be up to the geotechnical specialists to explain how the tests missed the structural fault in the limestone beneath Pier 97 and whether additional testing might have found it. McCue said Wednesday that the fault apparently was deeper than the soil testing went.
The column for Pier 97 extended 60.6 feet underground. McCue said a core sampling was taken to a depth of 73 feet at the center of the pier location. The flaw in the limestone that collapsed under the pier was at least 25 feet deeper than that, he said.
Several sinkhole experts said this week there are better ways to look for potential subterranean problems than drilling for core samples, including one called ground-penetrating radar.
Art Dillman, owner of All Coast Engineering Inc. in Brooksville, who has been performing sinkhole analysis for 30 years, said that Tuesday's collapse was avoidable.
"Ground-penetrating radar can see 300 to 900 feet below the surface," Dillman said. "It won't identify sinkholes, but it will show you where there are anomalies. Then, at least, you have a reference point for drilling to see what's there. The odds of hitting a sinkhole (when drilling at random) are about the same as hitting the lottery."
Dillman said the state refuses to keep up with available technology, but McCue questioned whether subterranean instabilities that exist a few feet away from a pier could affect the structure during its 100-year life.
"I've heard the theory of migrating sinkholes, but I don't necessarily accept it," McCue said. "I still think our testing was the best and most thorough that could be done."
Everybody was talking about odds Wednesday: What were the odds of the collapse happening? What are the odds of another one, especially after the road opens in the summer of 2005?
"The probability of a sinkhole in Florida is about 100 percent," McCue said. "The probability of a sinkhole forming under a bridge after it's built is nearly zero. It's never happened to my knowledge. It's as likely as getting hit by a meteor."
But McCue acknowledged that his agency could face a serious public relations problem in convincing motorists that the new elevated expressway is safe.
"If you're going to worry about this bridge," he said, "you're going to have to worry about every bridge in Florida."
- Times researcher Kitty Bennett contributed to this report.
