In the heart of Croatia, a transformative infrastructure project is reshaping the nation’s railway network, forging a faster and more efficient connection to Hungary. The 42km double-track railway modernization is a vital link in the European transport network, designed to improve freight transport efficiency and reduce travel times for passengers.

The sheer scale of the project is striking. It involves not only upgrading an existing railway but also constructing a brand-new parallel line, integrating major structures such as two semi-integral railway viaducts, multiple cut-and-cover tunnels, and a critical steel truss bridge over the Drava River, built using the incremental launching method (ILM). Beyond the engineering complexity, the project must align with modern railway standards, ensuring precise alignments and structural integrity.

At the forefront of this ambitious effort are Cengiz Insaat, the construction company responsible for delivering the project, and Radionica Mostova, the design firm overseeing structural engineering. With an ambitious completion target of late 2025, the team must overcome multiple logistical, environmental, and technical hurdles. The question is: how do they overcome these challenges while maintaining efficiency and precision? The answer lies in advanced digital modeling and collaboration, key areas where ALLPLAN is making a significant impact.

This is where ALLPLAN played a pivotal role. The software’s parametric modeling capabilities allowed engineers to refine and adjust viaduct and bridge designs with precision, ensuring alignment with real-world site conditions. The reinforcement detailing tools proved invaluable for the prestressed sections of the structures, where a combination of longitudinal and transverse tendons required careful planning. Collision detection in ALLPLAN helped engineers identify and resolve reinforcement conflicts early, preventing costly rework during construction.

“Prestressing is always complex, but for this project, the detailed modeling of tendons was critical,” said Rahela Mikulic, Bridge Designer at Radionica Mostova. “Each tendon has its own curvature, and ALLPLAN allowed us to model these with high accuracy, ensuring everything fit correctly.”

With these tools, the team successfully optimized structural elements while maintaining compliance with international railway standards, setting the stage for efficient construction.

Templates within ALLPLAN were also essential in accelerating workflows. The repetitive nature of elements like piers meant that traditional manual modeling methods would have been time-consuming and prone to inconsistency. Instead, engineers used template-based designs to quickly replicate elements while ensuring precise dimensions and reinforcement layouts. “We had 14 piers on this viaduct, ranging in height from 17 to 28 meters,” explains Kresimir Ilic, Chief Designer at Radionica Mostova. “Using templates in ALLPLAN significantly sped up the process, making our workflow far more efficient.”

Beyond the structures themselves, seamless interdisciplinary collaboration was crucial. With multiple teams working on structural, mechanical, and electrical components, ALLPLAN’s integrated BIM workflows ensured that models remained synchronized across disciplines. This reduced clashes between structural reinforcements and embedded elements such as catenary poles, drainage infrastructure, and pedestrian underpasses.

As construction progresses, the benefits of this digital-first approach have become even clearer. Engineers can quickly adapt to on-site conditions, adjusting reinforcement layouts or modifying alignment details as needed – all while maintaining precision and compliance.

But beyond just this project, the use of BIM-driven infrastructure design represents a broader shift in railway engineering. As transport networks across Europe undergo modernization, digital modeling tools like ALLPLAN will be essential for streamlining workflows, reducing errors, and ensuring that projects are delivered efficiently.

“This project required full collaboration between engineers, designers, and site teams,” adds Emre Yolal, Project Manager at Cengiz Insaat. “By working in 3D, we avoided unknowns during construction, which helped us stay on schedule.”

With the project set for completion in late 2025, it serves as a model for how modern infrastructure should be designed and executed. The lessons learned here – leveraging parametric modeling, enhancing collaboration, integrating reinforcement detailing, and the benefits of digital tools like ALLPLAN – are paving the way for more efficient, data-driven railway projects in the future.