Not every great engineering project is notable for its innovation; sometimes, speed saves the day. That’s often the case with emergency projects, when firms are recruited to salvage or replace damaged infrastructure and keep things moving in the wake of a sudden failure or catastrophic weather event.
Here, we highlight three recent emergency projects that did just that, delivering outstanding results amid challenging circumstances and tight timelines.
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Pittsburgh’s Fern Hollow Bridge connects three historic neighborhoods by stretching across the steep ravines of Frick Park, a picturesque natural reserve that belonged to a steel baron before opening to the public in 1927. The area surrounding the bridge is so densely wooded that it’s easy to forget that it’s also a thoroughfare accommodating 21,000 vehicles per day.
When the bridge collapsed early on a January morning in 2022, it fell more than 100 feet onto a recreational trail. The good news was that no one was killed. The bad news was both the damage to the park and the loss of a crucial and unique artery, causing substantial disruptions and delays to Pittsburgh commuters.
City officials quickly turned to their counterparts at the Pennsylvania Department of Transportation (PennDOT) to coordinate a bridge replacement project. Within a week, PennDOT turned to two companies, HDR and contractor Swank Construction Company, to expedite the design and construction of a replacement bridge.
From the beginning, the primary constraint was time: trying to get a new bridge constructed as quickly as possible. When HDR’s project team mapped out a potential project timeline, it quickly identified that traditional methods wouldn’t work. “If we tried to do everything in series, it would take four to five years,” says Jason Fuller, an HDR vice president.
So instead, HDR and Swank created a plan to pursue elements of the project concurrently, reducing the projected completion time to about 18 months. (It took them 11 months to partially reopen the bridge.)
But the new plan required intensive coordination. The Swank and HDR teams met weekly, and “everybody on the project dropped everything to be on that weekly call,” says Fuller. “We needed everybody there, and everybody did it.”
HDR worked quickly to complete the geotechnical engineering by examining original borings from the collapsed bridge and new borings from the foundation site. Fuller’s team also investigated the potential to build a larger bridge but ran into issues related to right-of-way and potential destruction or displacement of historical buildings. Another benefit of using the existing footprint was the ability to reuse some existing bridge walls and abutments, which weren’t damaged because the previous bridge collapsed inward. While HDR’s design for a new three-span bridge hewed to the same width as the old bridge, it also managed to better accommodate multimodal traffic by adding a 10-foot-wide shared-use path that’s separated from car traffic.
“We did most of our hard work in those first three months to get the deep foundations and then the piers and then the abutments—to get that stuff up, and then we knew the beams were coming,” says Fuller.
Yes, the beams. Getting the collection of 152-footlong, precast concrete beams to the construction site proved to be nearly as much of a challenge as the bridge design. The HDR team paraded through the campuses of Carnegie Mellon University and the University of Pittsburgh with a police escort while residents watched on lawn chairs.
But it worked, and the project was successfully completed with astonishing speed: City and state officials gathered at the new bridge for a ribbon-cutting ceremony in December to reopen the bridge to traffic, less than 11 months after the old bridge’s collapse.
The New York Hall of Science (NYSCI) learned a lesson in physics the hard way in the wake of Hurricane Ida, which hit New York as a post-tropical cyclone in late 2021: Water flows downhill. The museum is located at the very lowest point of the watershed in its community in Queens, and it lost about half of its exhibits after extensive flooding.
Rainfall in the area “literally all flows down towards the main entrance of the building,” says Aditya Bhagath, a senior associate at Thornton Tomasetti.
NYSCI hired Thornton Tomasetti to perform a climate risk and resilience assessment after the heavy rainfall and stormwater flooding caused by Ida, with the goal of ensuring the museum would be better protected against future weather events. As the Thornton Tomasetti team conducted a hydrologic analysis to predict the building’s future vulnerability, one thing that became clear is that “not all storms are the same,” says Julie Pietrzak, a principal at Thornton Tomasetti and leader of the firm’s resilience practice.
Some hurricanes allow for days of preparation and are notable for destructive winds. Others—such as Ida—intensify quickly and dump high volumes of water into an affected area in a short time. NYSCI remains especially vulnerable to the latter kind of weather event, which means its facility needs passive countermeasures that remain indefinitely in place—and thus perpetually ready for action.
At Thornton Tomasetti’s urging, NYSCI adopted a series of flood-mitigation measures that ranged from cleaning existing storm drains to ensure better performance to installing a system that prevents water backflow during a flood. The intervention most obvious to museum visitors is a custom-designed perimeter storm wall using a product called Muscle Wall—a series of water-filled barriers covered with an impervious membrane that surrounds the building and helps slow the spread of floodwaters.
The museum also agreed to change its main entrance, because the previous one was especially vulnerable to flooding. And although the museum reopened in February 2022, Thornton Tomasetti’s work with NYSCI continues; next up is a project to floodproof individual rooms inside the museum that house critical systems.
Severe flooding of Montana’s Yellowstone River in June 2022 destroyed homes and washed away roadways and bridges throughout a region that includes Yellowstone National Park. As Montana Department of Transportation (MDT) officials scrambled to respond, they identified a damaged out-of-service railway bridge near the city of Livingston that ran parallel to a popular highway bridge on U.S. 89 and decided to remove it before it posed an additional safety hazard.
During the railway bridge demolition in August, shrapnel from the explosion punched a hole in the webbing of the automotive bridge’s exterior girder nearly a foot wide—and suddenly MDT had yet another piece of damaged infrastructure to address.
MDT responded by calling in a team from the Denver office of Collins Engineers, expediting the process by repurposing an existing Collins contract. MDT was “able to mobilize us pretty quickly in an emergency scenario,” says Michael Banasiak, regional manager of Collins’ Denver office.
The Collins team was on site within a week and conducted a thorough analysis of the site, which included a magnetic particle examination and a drone-captured, threedimensional model of the bridge and surrounding area. The bridge also was quickly reopened to accommodate one lane of traffic—a key consideration given its crucial role in supporting regional trucking.
“We determined that due to the location of the perforation—close to the bearing on the extra girder of a four-girder bridge—we were able to keep the bridge open during the design and repair process,” Banasiak says.
The Collins team also concluded that while debris had struck several areas of the U.S. 89 bridge, the damage was limited to the hole. In about a month, Collins proposed a plan to fix the bridge by adding fill and splice plates to the affected area. MDT approved the plan and also tapped Collins to manage the on-site construction—both the repair to the U.S. 89 bridge and the cleanup of the demolished rail bridge. Banasiak supervised the work throughout the repair process, while also navigating supply chain challenges to ensure that the construction team had access to steel components.
The bridge reopened in January.
Steve Hendershot is a journalist based in Chicago. He has contributed to Crain’s Chicago Business, Chicago magazine, Chicago’s NPR affiliate WBEZ, and the Project Management Institute’s Projectified podcast.