Modular bridges provide on-demand infrastructure for disaster relief

For areas devastated by natural disasters—or lacking infrastructure—modular bridges save lives. UK-based Mabey Bridge creates sturdy spans, quickly, where they're needed most.

Courtesy of Mabey Bridge

A bus crosses a steel-truss bridge over a river in a tropical landscape

Zach Mortice

March 12, 2020

min read
The modular Rio Grande Bridge in Puerto Rico
Mabey Bridge built the 190-foot Rio Grande Bridge in Arecibo, Puerto Rico, in just 19 days. Courtesy of Mabey Bridge.

Invented in 1936 by civil servant and novice bridge designer Donald Bailey and pressed into service during World War II, the Bailey Bridge was critical to sustaining the pace of Allied advances in Europe. The bridge was made of a simple steel-truss system that could be connected section by section until it was ready for roller wheels to span it across hundreds of feet—an early triumph in rapidly deployable, modular infrastructure.

Gloucestershire, England–based Mabey Bridge has inherited and evolved the Bailey Bridge, but the original design still illustrates the company’s approach to modular bridging: products that are transportable, easy to build safely and quickly, require few components and construction equipment, do not require skilled labor, and place a premium on ease of transport. Today, Mabey Bridge is extending the legacy of the Bailey Bridge into new digital design and fabrication processes with greater levels of rapid deployment, mobility, and strength.

Part of the Acrow Group, Mabey Bridge has supplied modular bridging solutions to accelerate bridge construction and improve connectivity to more than 150 countries. It also has a strong history of disaster-relief work, supplying rapid-build emergency bridging solutions into disaster-stricken areas to provide immediate access to humanitarian aid and to enable post-event reconstruction. The company’s disaster-relief projects include post-tsunami emergency bridging in Sri Lanka and flood relief in the Philippines; Pakistan; and Puerto Rico, where after Hurricane Maria struck, the company replaced the Rio Grande Bridge in Arecibo in just 19 days.

Hurricane-devastated Puerto Rico is actually among the more accessible places in which the company works. “For a great deal of our customers, their challenge is getting high-quality infrastructure to remote places in the world,” says Tom Rasmussen, Mabey Bridge’s business development director. “We’re looking at giving world-class infrastructure to some of the most underdeveloped parts of the world. We manufacture products designed to be easy to transport because that’s what our customers value.”

The key factors for anyone in urgent need of a bridge are load capacity, span length, durability, and aesthetics. The Delta Bridge system is used for the most intense load requirements and can extend to 325 feet in a single span. Its Compact 200 (C200) model is ideal for rural applications and for rapid deployment in remote or difficult terrain after a disaster. The C200 is closest in design to the original Bailey Bridge and is the company’s most popular model. It can be built largely by hand, and its bulkiest sections weigh only 1,000 pounds—which is light enough to be loaded into a truck. “Once they’re in place, you can run a full highway load over them for many, many years,” Rasmussen says.

All bridge components are made to fit into standard shipping containers. “The end users want a product that is easy to build and is quick to deploy because that reduces the cost of the project and the time needed,” Rasmussen says.

Two soldiers lift a component of a modular bridge for assembly
The bridges are designed to be built simply on-site, with minimal tools. Courtesy of Mabey Bridge.

Given how disaster-zone conditions can change on the fly (a riverbank suddenly eroding, wildfires spreading, earthquake aftershocks), Rasmussen says the bridge systems can be lengthened or shortened on-site, in the midst of the chaos. “It takes no special skills to make these adaptations,” he says. “You wouldn’t have to create, weld, or cut new components on-site. That’s really important, especially if you’re in the teeth of a rapid deployment of infrastructure.”

Mabey Bridge’s design approach is to make the bridges’ jointing systems as simple as possible. Its innovative connection system, which uses bolts and pins to lock the modular components together, is simple yet delivers outstanding safety and structural integrity.

Traffic moves down a modular bridge flyover in the Philippines
The bridges may be used as permanent infrastructure, such as this flyover in the Philippines. Courtesy of Mabey Bridge.

This simplicity helps the company address labor and infrastructure limitations where its bridges are needed most. In underdeveloped regions, where skilled labor is at a premium, complex assembly requirements are a nonstarter. Many models require little more than wrenches, leveling tools, rollers to convey span sections, and a forklift. With these tools, smaller 130-foot bridges snap together in two or three days; longer bridges require eight to 12 weeks.

But quick assembly doesn’t mean brief durability. “We don’t design temporary bridges,” Rasmussen says. All bridge models are high quality and can become permanent infrastructure, though they can also be easily dismantled and relocated if required.

To spur digitalization and growth, Mabey Bridge sought out Autodesk technology in 2017. The company had identified two main challenges. First, it aimed to improve the customer experience and access to information, delivering quotes faster and reducing response times. Second, it wanted to enhance internal information sharing, streamlining processes for better efficiency. Teams often found they were struggling to manage the volume of requests from potential customers: Collating all the necessary information to generate quotes was challenging, resulting in delays.

In disaster scenarios where every minute is critical, communicating fully visualized specifications to clients—who are familiar with the territory and will be able to make adjustments—can be lifesaving.

A modular bridge crosses a river next to a collapsed bridge structure in Mozambique.
A Compact 200 bridge in Mozambique. Courtesy of Mabey Bridge.

“All of our products are modeled in BIM, both for factory-production purposes and for creating customer drawings and images,” Rasmussen says. “Our customers are requesting virtual models so they can incorporate them into their project BIM models in the planning stages. Scenario modeling is very easy in this situation—adjusting the bridge parameters, longer, wider, different locations—it can all be modeled very quickly. What if I wanted a longer span? You can flip on another augmented-reality view to see it. There’s value in that. And there’s lots of fun to be had.”

Mabey Bridge continues to research innovative ways of intelligently integrating its bridge designs into customer projects to realize the prefabricated future of the bridging industry; the Bailey Bridge was a precursor to that revolution. “The infrastructure of the future is going to be made in factories like ours,” Rasmussen says. “Just like the Bailey Bridge was. Modularity is where it is at, right now and for many years to come.”

Zach Mortice

About Zach Mortice

Zach Mortice is an architectural journalist based in Chicago.

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