Mammoet Keeps the Modules Moving at World’s Busiest Airport

By Felicity Landon

From Issue 5, 2024 of Breakbulk Magazine

When plans were being drawn up to expand passenger facilities at Hartsfield-Jackson Atlanta International Airport, the challenges included security, safety and scheduling efficiency – not to mention minimizing disruption to operations and passengers at the world’s busiest airport.

Concourse D, the airport’s smallest and narrowest concourse, is being expanded to enable it to handle larger aircraft and cater to more passengers, including widening the 44-year-old facility from 60 to 92 feet. This has necessitated building modules at a temporary construction yard set up on the south end of the airport, just north of the airport’s fifth runway, and over a mile from the concourse expansion site.

The main contractor for the project, a joint venture of Holder, Moody, Bryson and Sovereign (HMBS), subcontracted to Mammoet the task of lifting, transporting and delivering the modules to the construction site – involving meticulous planning and designing a custom solution for supporting the modules as they are lifted individually by a Self-Propelled Modular Transporter (SPMT). The modules are then carefully moved along 1.25 miles of airport runways and taxiways.

Mammoet is currently contracted to move ten modules in the first two phases of the expansion plan on the north side of Concourse D. “Planning started in 2022, we performed a test in February 2024, and we moved the first module in April, followed by four more over four weeks,” said Mammoet engineer and team lead Jay Solomon.

“In September we will carry out another test lift because the next five modules are a different size. Then, in January 2025, we will start to move the second batch.”

Finding the Best Solution

The modular approach was the best solution for reducing time spent going in and out of the security area, trucks entering and leaving, construction workers on site, and so on. “Because the modules are being built on airport property, it is easy to transport them and there is no need for large cranes inside the facility,” said Solomon.

Each of the first five modules moved measured 32 feet wide and 43 feet tall, with lengths ranging from 96 to 192 feet and a maximum weight of 583 metric tons. Most of the mechanical, electrical and plumbing fitting out was completed before moving; each steel module, with concrete decks, was fitted with metal panels on the outside and glass windows already installed.

Mammoet has been working closely with HMBS and the design engineers, Thornton Tomasetti and Sykes Consulting. Efforts were made to find a way to lift and transport the modules, based on the JV’s ideas, but there were challenges.

The lift points were placed in positions which meant the module could not be picked up in the middle since this could crack the concrete. The solution was to design a grillage support system to be placed between the module and the SPMT.

“We drive the SPMT underneath the module with the grillage designed according to the lift points, i.e. movable and adjustable,” said Solomon.

The transport has required 92 axle lines of SPMT with four power packs, with up to nine support locations and some axles shut off when required to create less bending. Further analysis of the structure and trailers led to the creation of some temporary bracing to ensure that nothing over-flexed during the move, leading to a crack in the module.

An additional challenge was that each module had to be set down into the ground at a greater differential than the plus/minus one foot typically allowed for on an SPMT. “We deployed 18 climbing jacks to help assist with the elevation difference,” explained Solomon.

Navigating Airport Restrictions

Physical management was only one part of the puzzle – Mammoet also had to work around time restrictions to allow the busy airport to continue operations. The first five modules were moved over five weeks, with the time allocated in each case between 1am and 4am on Wednesday.

“We had a three-hour window to move the unit, and we moved each one within one-and-a-half hours,” said Solomon. “So we were ahead of schedule each time.”

Each week, in a pre-set schedule, one module was moved into place early Wednesday morning. The SPMT remained onsite at least 24 hours to assist with and ensure the module was perfectly aligned, then the SPMT was driven back across the runways empty, to be reconfigured back at the construction site, ready to load and move the next module the following week.

Security was a major consideration. Before any opening of the fence into the airport, an outer layer of security was in place to cover the construction yard. Everyone entering the yard had to be pre-approved, with extensive background checks, ID and documentation processes.

Prior to moving each module, airport security came to the yard to carry out detailed inspections. Sniffer dogs were deployed to check equipment, module and onsite security. Anyone due to cross the fence was signed in, checked and required to wear airport security ID within the airport area.

There are “always” safety issues in a job of this nature, said Solomon. “But Mammoet is one of the best at that. We have safety meetings before and during the operations. If anything becomes different to what we plan, we stop and have a “Mammoet Minute” to discuss that and change accordingly. But there were no issues out there and everything went well.”

Temporary Bracing

“We are used to moving big cargo; 192 feet long and 500 tons is not that large for us per se, but this task presented some challenges – the modules were not necessarily designed to be moved, so we had to work with them to accommodate the stiffness of the structure,” added Solomon.

“This was done by adjusting hydraulic pressure locations in the SPMT to limit deflections in the module. Additionally, some temporary bracing was added to the module to stay within the allowable deflection limits. We have done many modules like this before, but airports are just beginning to incorporate this modular method.”

Looking ahead, a phase three expansion will follow on the south side and Mammoet is already advising the JV partners on design alterations to make the modules easier to move.

The modules will be at a more advanced stage of fitting out in the second phase starting in January and in the planned third phase. “They were cautious at first about what could be put in the modules, then realized they could put more in, so each phase is becoming more modular with more material/items inside,” said Solomon.

In the first two phases of the expansion, the first six modules are for widening Concourse D and the following four for extending it to the north.

Modular Approach Catches On

“Here in the U.S., there are a lot more airport expansion projects coming up,” reports Solomon. “We believe we have found a really beneficial way to expand concourses at airports – and to expand facilities in other industries,” he said.

“We have been moving modular units like this for years. Now, more and more people in different industries are learning about this approach and understanding it is a good way to keep costs down, improve safety and shorten schedules.

“In this case, we didn’t have all the trucks going inside the security fence with all the steel, etc. It was just a case of shutting the runway down for one delivery. That meant less disruption to the public and a whole new building delivered easily. We continue to incorporate some of the knowledge and lessons learned into phase 2 – it’s a case of improving with each move.”

Modular design is “the way of the future,” Solomon concluded. “It makes sense from the point of view of fabrication and installation. With our experience, Mammoet will be able to bring great value to other airport projects and into a wider range of construction projects.”

Mammoet is an exhibitor at Breakbulk Americas 2024.