Large public infrastructure projects rarely offer the luxury of a clean site. They are built in dense urban environments, phased around ongoing traffic, and shaped by strict safety and performance requirements. In seismic regions, these challenges are highlighted even more.
At Rome’s Pigneto district, Italy, a major railway and metro interchange project shows very concretely how seismic demands, construction phasing, and certification requirements translate into day-to-day engineering decisions on site.
A strategic interchange with clear constraints
The Pigneto project is a strategic infrastructure initiative designed to improve transportation connectivity in Rome. Valued at €131 million and partially funded by Italy’s National Recovery and Resilience Plan, it will link two regional railway lines with a metro line.
The technical challenge is not only the scale of the project, but its location and sequencing. Railway traffic must be maintained while foundations are demolished, rebuilt, and extended in stages. At the same time, the structure must meet full seismic requirements from the first construction phase onward.
“This is a very demanding infrastructure project from a technical point of view,” says Lorenzo Bianco, Managing Director of Peikko Italy. “You have strict safety requirements and seismic loads, with long-term implications for the surrounding urban area.”
Why construction phasing matters structurally
The foundations at Pigneto are executed in clearly defined phases. In the first phase, parts of the foundation slabs are cast while adjacent railway operations continue. In later phases, construction resumes on the same structural elements once traffic has been shifted.
To make this possible, reinforcement continuity must be guaranteed across construction joints. This is where Peikko’s MODIX® Rebar Couplers step in.
“They place the reinforcement in two steps,” Bianco explains. “The female part is installed during the first phase. When the second phase starts, the reinforcement is connected using the male part. Structurally, it behaves as a continuous bar, even though construction is interrupted.”
In a seismic context, these connections are not secondary details. They form part of the primary load path and must perform reliably under cyclic loading.
Certification as an enabling condition
For Italian public infrastructure projects, technical approval is a gatekeeper. Products must demonstrate seismic and fatigue performance using the national reinforcement steel grade before they can be specified.
“For railway projects, it is essential to show that the solution is approved for seismic loads,” Bianco says. “Otherwise, it is very difficult to even start the discussion.”
At Pigneto, this requirement directly influenced the choice of connection method.
“This project was possible because the MODIX® Rebar Couplers had certification for seismic and fatigue performance with the Italian ribbed bar steel grade,” Bianco notes.
From drawings to a working construction site
Once work started, the abstract requirements of certification quickly became practical realities. The site operates with around 130 workers per day, and delays or supply interruptions would immediately affect progress.
MODIX® Rebar Couplers were therefore produced locally in Italy by a certified partner. Within four months, more than 36,500 units out of a planned total of 50,000 units were pressed specifically for the foundation slabs.
“Local production was important,” Bianco says. “It allowed us to meet the required steel grade and react quickly when adjustments were needed during execution.”
Reliability under seismic demands
Although the principle behind reinforcement couplers is straightforward, their role at Pigneto is critical. Once cast into the foundation slabs, they become permanent elements of the seismic load-bearing system.
“In strategic infrastructure projects like this, reliability is everything,” Bianco explains. “You need solutions that behave in a predictable way, not only in calculations but also in real construction conditions.”
This predictability is increasingly expected by designers and authorities alike. Seismic performance is no longer assessed only through models, but through documented behavior, certification, and reference projects.
Seismic design as a practical driver
The Pigneto interchange is still under construction, but it has already become a reference point. According to Bianco, it was the first railway project in Italy to apply this approach on such a scale, and similar infrastructure projects are already following.
The project is a perfect example of how seismic design, when addressed early and concretely, enables complex infrastructure to be built safely and efficiently in challenging urban conditions. At Pigneto, seismic requirements shaped construction sequencing, detailing of connections, and approval processes from the earliest stages.
Long before the first train stops at the new interchange, seismic performance has already been built into the structure.