An engineer who first noticed that columns supporting a major interstate highway bridge in Delaware were tilting said he visited the site shortly after the bridge was closed and saw that they had shifted even farther.
The account of geotechnical engineer Dave Charles in an interview Thursday with The Associated Press suggests the potentially catastrophic problem may have unfolded quickly over a short period of time.
Charles said he told state transportation officials May 29 about possible problems with the bridge on Interstate 495 in Wilmington. He visited the site again Tuesday, a day after officials closed the bridge, and took another look.
"It was markedly different on Tuesday than it was on Thursday afternoon," he said. "I was surprised. There was a lot of movement."
Asked how officials did not notice until this week that there was a problem with the bridge, Delaware Transportation Secretary Shailen Bhatt also suggested the damage may have happened rapidly.
"The evidence, as it builds, is pointing toward a shorter-duration event, a rapid movement," he said.
That theory, coupled with Charles' observations, raises questions about why Delaware transportation officials waited until Monday to send crews to check the tilting bridge, which they then ordered closed immediately.
"I guess the question is, 'Should we have closed it sooner?'" Bhatt said at a news conference earlier this week. "When we got the appropriate information that there was a significant event going on, we closed the bridge out of an abundance of caution."
Charles said after he and a colleague working on an unrelated project near the bridge noticed May 29 that it appeared to be tilting, he sent matter-of-fact emails with cellphone photographs about 6 p.m. that day to an employee of the Delaware transportation department's bridge unit. Charles said the employee, whom he declined to name, acknowledged about 90 minutes later that he had received the emails.
"I think the person who received it took it seriously," Charles said.
State officials have said for days that they were first informed about a possible "anomaly" with the bridge late on May 30.
Asked Thursday when Delaware officials learned of the potential problem, Bhatt said in an email that "a low-level contact was made after hours" May 29 but not relayed to senior management until May 30, "at which point it became actionable information."
"Once alerted to the potential problem on Friday, our senior engineers asked for an inspection on Monday," he wrote. "In our view, DelDOT did not have information it could reliably act on until Monday - the same day that I was informed."
Engineers working with Delaware officials suspect a mound of dirt a contractor dumped next to the bridge, partly on the government's property, over several years. They think the weight of the dirt shifted the ground underneath the span and caused four pairs of columns to tilt.
Crews replaced a fence that previously marked the state's property. Its disappearance was discovered this week. Bhatt also ordered the inspection of other state bridges for similar problems.
The bridge, which normally carries an average of 90,000 vehicles on the I-495 bypass around Wilmington, will be closed indefinitely as engineers figure out how to brace it. Most of the detoured traffic is on already-clogged I-95, which passes through downtown.
Democratic Gov. Jack Markell visited Thursday. He said the federal government would pay 90 percent of the cost of permanent repairs to the bridge and had already approved $2 million in emergency funds. The cost of fixing the bridge hasn't been determined.
"This is unbelievable," said Markell as he examined walls separating the northbound and southbound lanes of the bridge. The walls are normally level with each other but are now separated in height in some spots by up to 18 inches.
Markell said he was grateful Charles notified the state of the problem.
"Thank goodness he, with his skills, and his knowledge, and his powers of observation, were there," Markell said. "Based on what I know, we certainly owe him a debt of gratitude."
Charles doesn't consider himself a hero.
"I don't know whether we saved lives or not," he said. "Somebody else might have found it later. I think we did what professionals with our type of training need to do."