How DOT determined the Gold Star Bridge was safe to reopen after catching fire

Editor's note: Some terms in this article have been defined using the Ohio Department of Transportation's Glossary of Bridge Terms.Groton ― When Gov. Ned Lamont held a news briefing at 3 p.m. on Friday, April 21 about the fatal Gold Star Memorial Bridge accident from 11:15 that morning, Connecticut Department of Transportation Commissioner Garrett Eucalitto said of the southbound span, "It's going to be an extended closure. We don't know how long, until we're able to do an extensive analysis of the structure."The Gold Star Memorial Bridge's two steel truss spans carry Interstate 95 traffic over the Thames River between New London and Groton. Given the shock of the earlier plumes of black smoke emanating from the bridge, there was some surprise when two southbound lanes opened three hours later. Additional lanes opened the following morning, but the right-hand acceleration lane and pedestrian walkway remain closed.So, how did DOT officials determine the southbound span was safe to open after a crash with a fuel truck led to flaming fuel running along the bridge? What does a structural analysis entail?"The Gold Star Bridge was inspected by experts immediately following the crash, which is why it was able to reopen several hours later," DOT spokesperson Josh Morgan said in an email Wednesday. "Under no circumstances would that bridge have been reopened if there were any safety concerns."Division Chief of Bridges Bart Sweeney said the fire started on the deck of the bridge and traveled down the drainage scupper, an opening for water accumulated on the roadway to drain. The fire traveling down the scuppers is how the superstructure got exposed to the fire, leading to questions about whether the fire impacted the structural integrity of the bridge.Sweeney said he was one of six DOT workers whose primary focus was the structural integrity of the bridge ― and it turns out there's a lot engineers can determine through visual cues.But first there was the initial response. Paul Rizzo, bureau chief of highway operations, noted that the operations center in Bridgeport co-habitates with Connecticut State Police Troop G, so they find out about incidents when state police get 911 calls. DOT also has cameras near the bridge.Rizzo said service patrol vehicles immediately responded. Once DOT knew what was going on, they started dispatching maintenance, bridge and electrical crews, along with the director of District 2 and managers that oversee maintenance of the bridge. Rizzo headed to the scene from the Southington area.He said between state and contractor employees, DOT had about 75 people supporting the bridge response from the day through the night.As principal engineer of Bridge Safety and Evaluation, Mary Baker got a call from the operations group in Bridgeport and first looked to see what staff and equipment were available.A project to repair and strengthen the northbound span, which received a "poor" rating for its deck and superstructure in 2019, began last year. U.S. Secretary of Transportation Pete Buttigieg visited the bridge in January to highlight a $158 million federal grant for repairs to the northbound span.The inspection report for the April 21 incident says Baker was notified at 11:35 a.m. and initiated the investigation. The report said the roadway showed about 420 feet of fire damage to the lane off the right ramp and the shoulder area.There was also about 400 feet of damage to the parapet ― the concrete wall on the outer edge of the roadway ― and railing mounted on the parapet, and 300 feet of damage to the sidewalk. The fence and supports sustained 320 feet of damage, and so a temporary chain-link fence is in place.According to an April 26 memo from Scott Hill, chief engineer in the Bureau of Engineering and Construction, Office of Bridge Safety personnel arrived around 2 p.m. They didn't yet have access to the top of the bridge, as state police were still working on accident reconstructionBut they were granted access below the bridge, which Sweeney said "is the most critical area for us to start with.""We want to look at the integrity of the foundations of the bridge, of the bearings that hold the steel up, and then the steel itself," Sweeney said. The first steps are understanding where the fire was located, what sort of fuel was associated with the fire, how long it burned, and how long the burn affected the structure, Sweeney said. The next phase is a visual inspection."The internal temperature of the steel is very critical to these assessments," Sweeney said. But since his team wasn't there when the fire was burning, they couldn't measure the temperature, so visual cues are important.Workers used the 135-foot manlift to look at the fire pattern on the superstructure ― the large beams with the truss ― and determine "if there was any damage done to the structure because of excessive heat and excessive duration of heat."Noting that material generally expands when heated, Sweeney said the first good sign was there was no deformation in the flanges, which are the horizontal parts of I-shaped beams, or buckling in the portion between the flanges. Looking at the superstructure from the bridge down to the bearings, Sweeney said they "saw no signs of distortion."He said the next thing they look at to determine steel temperature is the paint, because paint begins to fail around 750 degrees and completely fails at 1,100 degrees. Inspection crews took soot from different locations to confirm the paint system remained intact."As long as temperature stays below 1100 degrees, the structural integrity is not compromised," Sweeney said. Workers looked at the external paint and the paint on the backside, finding "no deficiencies in the paint system."A third positive sign was the 11:44 a.m. call Sweeney got from the deck saying the fire was out."A half-hour duration is also a key indicator that the steel was not exposed to fire sufficiently long to bring its temperature up to that critical temperature," he said. Sweeney said if the superstructure had been jeopardized, DOT was looking at an alternate plan to push southbound traffic onto the northbound span.Asked whether the southbound rehabilitation work that began in 2017 had any impact on preventing the aftermath of the accident and fire from being worse, Sweeney said no, that "the structure was already prepared to survive an event like this."Rizzo thinks that fuel spreading out and burning "was probably better than being in a concentrated location and burning." By comparison, he recalled the concentrated and long-burning fire on the I-95 Howard Avenue overpass in Bridgeport in 2004.That incident was also the result of an accident between a car and a truck carrying home heating oil, but unlike on the Gold Star Memorial Bridge, the fire melted the bridge superstructure. The southbound lanes were closed for six days, until a temporary bridge opened.Reopening the bridge and next stepsRizzo said as Sweeney's team did its assessment underneath the bridge and it became clear the left two lanes could likely reopen, the highway operations team was coming up with a traffic plan and acquiring the needed materials.Between arriving by 12:30 and leaving around 9 p.m., Rizzo coordinated with state police and communicated as much info as he could to Commissioner Garrett Eucalitto. Rizzo was back early the next morning, with a target of opening more lanes by noon. This happened, though the acceleration lane, shoulder and sidewalk remain closed. Sweeney, who went up top after doing work below the bridge, also said there was a lot of damage to the parapet and so DOT also had to assess whether the fire jeopardized its integrity.He said the spalling of the concrete was 2 to 3 inches deep but not enough to see the reinforcing bars, which are what give the parapet its strength, so DOT felt the parapets still had structural strength.DOT spokesperson Josh Morgan said Wednesday the agency is awaiting a report from consultant Michael Baker International, from a follow-up inspection, before determining if lab testing of the parapets and deck is needed. The results of the inspection will determine whether the parapets can be rehabilitated or if they need to be completely replaced.Morgan said MBI is also assessing the sidewalk, and there is no word yet on when it will reopen. Baker said DOT is tracking expenses related to its work on the bridge, which are mostly labor and equipment, and Morgan said he doesn't have an update yet on what kind of reimbursements it could get either through insurance or the federal government.e.moser@theday.com