The National Transportation Safety Board has all but concluded its investigation into the March 2018 Florida International University pedestrian bridge collapse, which killed six people and injured several others. Its findings, foreshadowed by an earlier report from OSHA's Office of Engineering Services, laid the majority of blame on the span's design but also revealed major gaps in the project's construction and safety protocols.
The big question is, what can the rest of the industry learn from this tragedy and how are these lessons likely to manifest themselves in future bridge projects?
In its report, the NTSB put forth 30 findings, many of which targeted FIGG Bridge Engineers' design. The agency determined that FIGG made load and capacity errors in its calculations, which resulted in an underestimation of load and an overestimation of capacity, particularly at the 11/12 nodal region. This is the area that exhibited significant cracking — about 40 times bigger than usually seen in concrete construction — prior to the collapse.
The NTSB also named the lack of peer review by FIGG's consultant firm, Louis Berger, as a contributor to the collapse, along with failure on the part of many project players to recognize and act on the severity of the cracks.
FIGG has disputed the NTSB's conclusion that the collapse was a result of design errors. The company issued a statement detailing its own investigation into the cause of the bridge's failure, and its experts determined that the failure of construction crews to roughen cold joints at the 11/12 nodal region was to blame.
"Everybody needs to be able to push the stop button and say, 'I don't like the way this is going.'"
Civil and environmental engineering professor, Northwestern University
Typical bridge design procedure, said Amanda Bao, associate professor in civil engineering technology at Rochester Institute of Technology, will usually see the engineering company produce a set of calculations, with an independent firm performing a design check.
"For this bridge," she said, "it seems both sides made mistakes."
Not only did the NTSB fault FIGG and Louis Berger for not catching the calculation errors, but Louis Berger was also not qualified by the Florida Department of Transportation to serve in such a capacity.
Bao said that's one area where the process could use reform — ensuring that the company hired to perform an independent review is qualified to do so. A double-check of the scope of work that is included in the independent peer review firm's contract is also something design companies might want to do as well, she said.
Louis Berger reportedly lowered its original bid amount and therefore did not have the budget sufficient to evaluate the bridge nodes or to perform inspections at different stages of construction.
The design check, Bao said, should include a complete set of design calculations. In fact, she said, the Florida DOT should probably insert stricter language into its manuals as to how officials want design-check calculations handled.
The NTSB had recommendations not just for the design and construction teams but for the Florida DOT as well. First, similar to Bao's suggestion, the NTSB advised the department to revise its "Plans Preparation Manual" to require an independent peer review of design calculations used for all nodal forces for certain bridge types.
The NTSB also suggested that FDOT do the following:
- Require independent review firms to submit a qualification letter.
- Revise local agency program agreements — FIU was the local agency overseeing bridge construction in this case — to require traffic under or around bridges be stopped if structural cracks should appear while the bridges in question are under construction.
- Inspect local agency program bridges that have an uncommon design.
- Include a discussion about redundancy, particularly for uncommon bridge designs, in the state's "Structures Manual, Structures Design Guidelines" publication.
In the future, Bao said, in addition to calculations for the bridge, design companies probably need to perform redundancy checks. For example, they might want to factor in losing a member and see how the bridge structure behaves in that scenario.
It's also dangerous, Bao said, to rely on a single source to address a potentially major safety issue. For example, if a contractor is concerned about structural cracks, it should report it not only to the design firm but to another party with the authority to stop the project and perform a review, such as a local agency or the state DOT.
In the FIU case, she said, it seems like everyone took the efficacy of FIGG's design for granted. This was the first time this bridge design had been used, she said, and perhaps there should have been extra steps built in to ensure that the design worked and that extra measures were taken during construction to monitor safety issues.
No doubt, said Dan Hanson, senior vice president of management liability and client experience for Marsh & McLennan Agency’s Minneapolis operations, insurance carriers will also be more aware of potential safety issues while performing jobsite inspections for projects like these. Insurers end up paying the claims, and they have a vested interest in making sure their clients are working as safely as possible.
While loss control teams that perform jobsite inspections wouldn’t be looking for structural defects, he said, they would certainly be looking for conditions that could be dangerous to workers or to the public.
At the very least, said Joseph Schofer, professor of civil and environmental engineering at Northwestern University, what companies involved in bridge construction might learn from this actually falls outside the bounds of the NTSB findings, and that is proper communication.
When companies are working on a complicated process like this with a relatively new method like accelerated bridge construction (ABC) and a problem arises, he said, there likely would be a real advantage if the parties either were in one place or were on a video conference where everyone was looking at the same thing at the same time.
"I would say learn something about communication and sharing information and doing it very rapidly," Schofer said.
There is also a similarity, he said, between the FIU incident and other disastrous accidents like airplane crashes where the evidence reveals that there was not just one contributing factor but multiple factors and that even in the face of tight schedules, there were points in the timeline where someone might have been able to raise a hand and put the project on pause so that the situation could be examined more closely.
"Everybody needs to be able to push the stop button and say, 'I don't like the way this is going,'" Schofer said.
In addition, he said, the first line of oversight, before a peer review, is the team's own calculations, and rechecking those by various means could be critical. For example, a spot check of computer-generated calculations by hand or vice versa could help in verifying the model.
There could be some concern on the part of ABC advocates, he said, that the FIU incident will undermine the momentum that the ABC method currently has. The method, also known as rapid renewal, essentially boils down to being a process that allows teams to build a bridge in some location other than its future footprint and then install it on-site in as little as a day.
"I think if [the collapse] is going to do anything, it ought to tell the people that are doing design and construction in [ABC] to be careful, be thoughtful and don't [treat it as] routine," Schofer said. One of the arguments for ABC, he said, is that it won't disrupt traffic for very long, but there may be cases where crews have to do so in order to ensure safety.
The FIU collapse could impact how construction contracts are written as well. They could, for instance, include more about crisis management and emergency protocols, said attorney Ross Boden with the law firm of Sandberg Phoenix & Von Gontard PC in St. Louis, focusing specifically on who is in control and what should be done in the event of a safety concern.
"I would definitely expect an increased focus on safety procedures and protocols in construction contracts," he said.
One might suspect there will be more language regarding safety requirements, although most contracts likely address those concerns already. For instance, there are several places in the American Institute of Architects' "A201 — General Conditions of the Contract for Construction" document. In fact, FIU's 2014 Request for Proposals for the pedestrian bridge that collapsed said that public safety was a "primary expectation" from those wishing to bid on the project.
However, Boden said, even specific language addressing exactly what went wrong at FIU isn't a guarantee that work will proceed without a breach in safety procedures. "There may be an increased focus on safety concerns and procedures in construction contracts, but at the end of the day, you can't prevent human error," he said. "It's just not possible, certainly not by contract."
Contracts moving forward, said Jason Kellogg, partner at the law firm of Levine Kellogg Lehman Schneider + Grossman in Miami, could include more redundancy in oversight where different trades may insist on the ability to check their teammates' work. More owners, he added, could also put one person with the requisite expertise in charge, giving that individual the last word on major issues facing the project.
"Firms need to take greater steps to ensure communication and collaboration and really focus on what could happen if that fails."
Partner, Levine Kellogg Lehman Schneider + Grossman
Or things may stay the same, he said, with companies carrying forward the knowledge that if they don't do their jobs the right way, they could put lives in danger.
Echoing Schofer's sentiments, Kellogg said that mistakes could have been made on the project because of a lack of communication. "Firms need to take greater steps to ensure communication and collaboration and really focus on what could happen if that fails," he said.
"Hopefully," Kellogg said, "the silver lining is that it reminds everybody that you're working as a team."