Drones flying over I-95 bridge inspecting the span
NEW HAVEN — Drivers crossing the Pearl Harbor Memorial Bridge recently may have seen drones flying over and under the deck, and up beside the towers.
They are taking photos of the bridge’s surfaces, including cracks first noticed in 2017, which have yet to be repaired or sealed, according to state Department of Transportation officials.
The project to repair the cracks and breaks in the concrete, which officials say do not threaten the safety of the bridge, is scheduled for 2024, according to Tim Fields, principal engineer for major structures, who oversaw the latter stages of the bridge’s design and its construction.
The drones still are being tested by the DOT, which has used them on other bridges, including the Gold Star Memorial Bridge between New London and Groton, according to Mary Baker, who oversees the DOT’s bridge inspection unit. The agency has previously used “snooper-trucks,” lifts and ropes and climbers for such inspections.
“We’re trying to develop the baseline for future inspections,” Baker said.
The inspection is being done by Atane, which has an office in Wethersfield. The drones are run by Lumina Lidar, a womanowned business in Greenwich.
Baker said the drones will continue flying through the end of the year, with two lanes of the bridge closed at times during weekends and one lane Mondays through Wednesdays.
A 2019 inspection also found spalling, areas where the concrete surface had broken, including some where rebar was exposed. Photos in the report show that the bridge has seen wear in the six to nine years since it opened (the northbound span opened in 2012, the southbound in 2015). In 2019, it had average daily traffic of more than 73,000 vehicles, 9 percent of them trucks, according to the report.
“It’s possible there might be some areas that need to be replaced, but we’re not expecting wholesale replacement,” Fields said. But he said the current inspection will determine “what action should be taken to extend the surface life as long as possible.”
Fields said the cracks and other signs of wear are not a threat to public safety.
“We’ve seen nothing here that would arouse concern about safety issues with the bridge,” he said. “We’re doing our due diligence.”
“Hopefully, we’re just going to be sealing cracks here,” Fields said. “It’s a little disappointing that we’re faced with some of the cracking that we have now. It’s really not something unexpected.”
The Q bridge, which got its nickname because it crosses the Quinnipiac River as part of Interstate 95, was the first extradosed cable-stayed bridge in the country. Two years later, an inspection found a number of small cracks in the surface, leading to a “fair” rating by HAKS, the inspector in 2017.
The ratings for the 4,600-foot-long bridge did not change from 2017 to 2019, with the condition of the deck, substructure and the channel and channel protections all given a 7.
The superstructure’s condition was rated 6, or fair. The overall rating is based on the lowest component’s rating.
The girders on which the deck rests are huge, hollow concrete boxes, with a 21⁄2-inch-thick layer of latex-modified concrete on top of the bridge deck, which is at least 8 inches thick. During construction, as each box girder was added to the spans, the stress would cause minor cracks in the overlay, Fields said.
“It’s not considered structural. It’s the riding surface of the bridge,” he said.
“We have a few bridges around the state that have these types of overlays,” he said. “They’re generally long-lasting overlays.”
The latex-modified concrete on the Yankee Doodle Bridge in Norwalk has lasted more than 30 years, he said.
The cracks may have developed so much sooner on the Q bridge because of the construction method, Fields said.
“We used state-of-theart specifications,” he said. “There’s challenges that go with that because excessive wind or low humidity can be associated with that.”
It also may have been the result of “how quickly curing mats were put on the concrete,” he said.
According to the 2019 inspection report for the northbound span, “Based on the 2019 crack tables, there are 70,220 linear feet of cracks. Also, there are 49 linear feet of cracks have active leakage … and require attention.”
On the southbound side, inspectors found there were 54,558 linear feet of cracks but none with active leakage. The 2019 inspection was conducted by AI Engineers of Middletown.
Repairs
Fields said there were several reasons why the timeline for the repair project has been extended out to 2024.
“We’ve experienced some delay administratively in funding the new project and preparation of scope of work with the consultant,” he said. “We are also planning some additional worker safety access and lighting improvements in the project.”
He said the crack repairs are not considered “emergency in nature.”
James Falconer, owner of JKF & Associates, an engineering firm in New Haven’s Erector Square, said “sealing the cracks is a priority.”
Falconer said there is no reason to be overly concerned about the bridge’s condition, however. Having worked with Fields in the past, he said, “he knows what he’s doing. There’s no dangers here.”