GREEN BAY, Wis. — In the dark of night, a truck driver heading across the Interstate 43 bridge across the Fox River felt something strange on the road underneath his rig.
So strange that he reached for his cellphone and dialed 911.
When the trucker reported that the pavement on the Leo Frigo Memorial Bridge seemed to be sagging Wednesday morning, the police dispatcher either could not understand what he said — or could not believe it.
"Sagging?" she asked.
The trucker repeated himself and urged the dispatcher to take action.
"I would suggest," he said, "that someone go out there and at least take a look at it."
It was 3:43 a.m.
After being dispatched to the bridge to investigate, a Green Bay, Wis., police officer reported about 10 minutes later that nothing appeared unusual. The officer told the dispatcher: "Bridge appears to be intact and not sagging. No apparent damage to bridge," records say.
It would be almost another hour before police officers realized that the 120-foot-tall bridge had, in fact, sagged and that the four-lane interstate highway should be shut down.
Police Lt. Jeff Brester said it appears the officer first on the scene of the bridge was mistaken in the initial assessment or the problem with the bridge worsened later. Noting that the Leo Frigo bridge typically carries 40,000 vehicles a day, Brester said other motorists surely would have taken notice of a situation as serious as sagging pavement.
"If it was as bad as people are saying at that time, I would think we would've gotten more calls," he said.
Soon, there were more calls.
At about 4:45 a.m., another truck driver, Richard Maufort, called 911 to report that conditions on the bridge were "not quite right."
Maufort, who delivers automobile parts to car dealers, recalled that something was amiss when he crossed over the bridge heading west about 4 a.m. On his return trip in the other direction, Maufort decided to alert the authorities to the sagging pavement.
The 57-year-old De Pere, Wis., resident later learned from radio reports that the situation was serious enough that police had closed the bridge.
"I'm glad nobody got hurt," he said. "I'm glad they found out what the problem was."
By 5:30 a.m., the bridge was closed to all traffic.
State highway officials soon determined that one of the piers supporting the bridge inexplicably sank into the ground, causing the 84-foot-wide structure to dip about 2 feet.
Built in 1980, the bridge carries traffic along Interstate 43 in Green Bay and represents one of city's most vital thoroughfares. Officials have indicated that it could be months or even a year before the bridge, named in honor of the former president of Frigo Cheese Corp., is back in service.
Engineers with the Wisconsin Department of Transportation and the Federal Highway Administration are trying to determine what caused the problem and how it can be fixed.
Jason Lahm, a state bridge maintenance engineer, was getting ready for work when his phone rang at about 5 a.m. The caller from the state's traffic operations center in Milwaukee told Lahm there were reports that the Leo Frigo bridge was sagging.
Lahm, who has been with the department for 11 years, was the first state highway official in the Green Bay region alerted to the problem. Although skeptical that the bridge deck really had sunk, he rushed to the scene, arriving there about 30 minutes later.
Police had already closed the bridge, and Lahm could see for himself that the reports of sagging pavement were true. His first thoughts were of disbelief: "This can't happen."
But he called his supervisor and reported that the bridge would probably have to remain closed for a long time.
"I could determine that we had a significant issue as soon as I got to the site," Lahm said. "It was very obvious as soon as I saw it."
State highway officials say they have calculated that the pier sank into the ground sometime between 9 p.m. Tuesday, Sept. 24, and 5 a.m. Wednesday, Sept. 25.
According to police records, two motorists drove around police squad cars and crossed over the bridge before officers sealed off the thoroughfare with barricades, detour signs and flares. The towering structure has been closed to traffic ever since.
Eyewitness Dale Ferron of Algoma, Wis., said he noticed the pavement problem en route to work about 3:45 a.m. Wednesday. The mail delivery contractor recalled being jostled in his car and then seeing a truck's headlights bouncing around behind him.
"It made my heart skip a beat," he said. "It was kind of like being on a roller coaster."
After arriving at work on Green Bay's west side, Ferron, 49, found himself troubled by thoughts that the bridge could be unstable and that other motorists could be in danger. So he grabbed a phone and called police.
Like so many other people, Ferron now is left wondering what caused the problem.
Or, as he put it, "Why all of a sudden now?"