Hamburg Central Station: coordinating complex construction projects with a digital twin

Trains arrive and depart, passengers change platforms, shops stay open and technical systems must keep working. At the same time, the station is being planned, built, maintained and remodelled. Hamburg Central Station therefore faces two inseparable demands: it must change while continuing to function.

With more than half a million people passing through every day, Hamburg Central Station is one of Europe's busiest railway hubs. Keeping it running and maintaining its buildings present exceptional infrastructure challenges. Numerous projects with different objectives and clients are planned or under consideration for the coming years. They affect one another and must therefore be coordinated across project boundaries. If several construction activities need the same circulation, logistics or assembly space at the same time, their work areas can overlap. Without coordinated management, this can put passengers at risk or cause costly disruption. Meanwhile, station management must keep the building operational.

A digital twin (DT) can provide a central approach to managing this complexity. It differs fundamentally from a static building information model created using Building Information Modeling (BIM). A BIM model records a structure's geometry and properties at a particular point in time. A digital twin goes further: it continuously connects the physical structure with its virtual model and introduces a fourth dimension:

At a complex transport hub such as Hamburg Central Station, space alone is not enough. Time must also be part of planning. Coordinating projects that overlap in space and time therefore calls for model-based 4D methods. These link three-dimensional models to their respective schedules, revealing not only where construction will take place but also when particular areas are needed. Model-based methods can coordinate construction, logistics and circulation areas during ongoing operations, while identifying technical dependencies and opportunities to combine activities.

A centrally maintained data source also avoids repeated surveys of existing assets. It enables future conditions to be simulated and designs to be based on current asset information rather than outdated records. Once a project is complete, the data should pass seamlessly into operations. This includes updated as-built geometry recording what was actually constructed, maintenance data for systems such as SAP-PM, and information to support defect and warranty management.

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Synchronising multiple projects in a 4D digital twin

As part of BIM management across the projects, those responsible have worked to establish model-based coordination of existing assets, operations and all planned construction work. This dynamically connects construction and operational requirements. The aim is to manage construction and maintenance so that Hamburg Central Station continues to operate throughout.

Semantic models of the existing assets provide the basis for planning and synchronising project models. They contain not only a component's geometry, but also information about what it is and which properties it has. This creates a common basis for the technical planning and scheduling of construction work that affects operations. Building these models requires both geometric and semantic capture of the structures and technical systems across the entire station.

Semantic modelling alone is not enough to manage several projects simultaneously. Integrated 4D modelling also links the geometric 3D submodels of every project to their schedules and can project them up to a decade into the future. To identify spatial conflicts automatically using rules, the model includes more than the components that will remain permanently in place. It explicitly represents temporary site facilities, logistics routes, scaffolding and work areas. Standardised space objects can act as digital placeholders for these temporary areas. For example, the model can reveal that one project needs scaffolding in the same location and at the same time as another project's transport route. Either use would fit the space individually, but their schedules conflict.

Virtual Design Reviews (VDR) and model checks across projects

To make the 4D model part of project management as well as a technical planning tool, it is incorporated into Virtual Design Reviews (VDR) across the projects. These are joint coordination meetings in which the models are analysed in space and time. The process follows three clearly defined stages:

• Preparation: Subproject managers submit current status reports and updated 4D submodels to a central collaboration platform. The models are checked for data quality and 4D clashes.
• Review: The combined models are analysed visually and over time in the VDR meeting. Predefined viewpoints and dynamic section planes make spatial and scheduling interfaces clear for discussion.
• Follow-up: Identified conflicts and other findings are recorded as BCF issues in a common data environment (CDE). They are tracked through to resolution or documented against the model for future use. This vendor-neutral exchange format links tasks and issues directly to a specific location or view in the BIM model without requiring the entire model to be exchanged.

As part of the model checks, the team responsible for BIM management across the projects carried out rule-based 4D clash detection. This adds time to conventional 3D clash detection, identifying dynamic conflicts when two objects or placeholders require the same space at the same time. All discrepancies are recorded, referenced and tracked as structured topics in the vendor-neutral Building Collaboration Format (BCF).

Intuitive data integration for station management

Alongside coordination across projects, another requirement was to give station management staff mobile access to the geometry of existing assets and current information about them. Access to the digital twin therefore needed an intuitive interface suitable for mobile devices. A bidirectional connection between the 3D asset models and the ERP system SAP-PM enables maintenance teams to access spatially located equipment master data and current operational records, including fault reports, maintenance plans and inspection reports, while on the move. This supports targeted maintenance and a rapid response to repair needs.

In future, the digital twin could also connect to defect and warranty management so that progress can be tracked for each object. As the station's operator, station management could then monitor its condition in real time.

Another digital twin use case is to combine geometry and contract data for food service and retail premises from different sources into a shop profile. This brings together all information about a leased space that is relevant to both marketing and administration.

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Conclusion: lessons, scalability and further development

Implementing a digital twin for Hamburg Central Station means overcoming complex challenges:

• Existing assets must be recorded in both geometric and alphanumeric form, and different IT systems and interfaces must work together. This also requires an organisational shift towards closer collaboration based on shared data.
• These efforts bring substantial benefits. A central data source that avoids duplication reduces costs and improves project coordination. Simulations using the digital twin also help align parallel construction projects with ongoing operations and give station management the information it needs.

Successful implementation requires a structured, phased approach:

• First, define the objectives, stakeholders and priority use cases.
• Then analyse existing data sources and processes.
• Only on that basis should systems be selected, interfaces developed and the necessary IT environment established.

A digital twin of Hamburg Central Station is therefore much more than a technological representation. It is a central strategic tool for the comprehensive, collaborative management of information and operations in the future.