Based on the results of the analysis, several areas for improvement in BIM planning and execution were identified that can be optimized. These areas for improvement fall under Level 3 of the DIKW pyramid, Knowledge (see Methodology). They are listed below, organized by category.

Contract

Although there are currently sample templates for AIA and BAP, they are incomplete in terms of the BIM strategy being pursued, the specifications for information requirements and model creation, and the data transfer processes. More precise specifications in this area can help avoid change orders and conflicts regarding the scope of work and services to be provided.

Software and Communication

The projects examined utilized various CDEs, and in some cases even two within a single project. These CDEs had different feature sets and offered varying capabilities for model-based project management and communication. Optimizing this aspect could make it easier for all stakeholders to get started on a project. Furthermore, the software used should not restrict or hinder the planned workflow; rather, BIM workflows should dictate the requirements for the software.

Model

The contract documents contained inconsistent and, in some cases, missing requirements regarding model quality, level of detail, and attribution. Furthermore, models often could not be imported from the preliminary design phase because the model requirements did not align across the project phases. Furthermore, there was often a lack of clear identification of objects, making it impossible to track their changes throughout the planning process. Here, content should be modeled only once and then updated, with clear identifiers that make the development of an object fully traceable across the project phases. Clear requirements for the model can also ensure that there is less need for subsequent modeling and attribution.

Execution

There was a perceived need for optimization in the area of execution, particularly with regard to AWFs “120 - Termin- und Bauphasenplanung” (Schedule and Construction Phase Planning) and “140 – Baufortschrittskontrolle” (Construction Progress Monitoring). The effort involved here must be significantly reduced so that the benefits can once again be more clearly recognized.

Based on the analysis and the identified opportunities for optimization, the following recommendations for action were developed as Level 4 in the DIKW pyramid (see Methodology).

Overall

The German federal government’s primary goal was to establish end-to-end digital processes in the construction industry through the phased plan [1]. This is intended to increase efficiency, reduce planning and execution times, improve the quality of execution, and generate a wealth of usable data for facility management. End-to-end digital processes can only be achieved by applying BIM to the entire project. All project phases (LPHs) should be covered, and all AWFs should be implemented whenever possible. If this does not appear feasible following a thorough cost-benefit analysis, at least sequential AWFs with clearly defined data and model handovers should be applied.

Furthermore, consistent digital processes also require regular updates to the models. Particularly between project phases, it must be ensured that the model quality is sufficient for the next phase and that no new modeling is required.

To ensure that the requirements are implemented as effectively as possible, well-trained personnel are also needed. Periodic training and professional development for all parties involved, on both the client and contractor sides, is recommended. Likewise, during the contracting process, strict attention should be paid to ensuring that the contractor’s experience is sufficient for the project.

BIM-Strategy

A key component in ensuring the successful implementation of BIM in a project is the formulation of a binding BIM strategy that applies to all DB projects. One example is the “Guidelines for the Application of BIM Methodology” issued by the Geschäftsbereich Personenbahnhöfe of DB-IG [2]. A BIM strategy should define the following points:

• BIM goals
• BIM use cases (AWF)
• Terminology
• Basic concepts of IT, geodesy, and BIM fundamentals
• Specifications for data exchange and delivery
• Quality assurance processes
• Standardized requirements for a CDE
• Modelling guidelines

Geometry Object Model

Just as the SOM defines the attributes of the models, a clear, standardized specification of the geometric level of detail is required. A suitable designation for this would be, for example, the Geometry Object Model (GOM). This GOM should define the required LoG in detail for each project phase and each architectural work phase for all objects to be modeled. In addition, it should describe which details are required for the respective LoG, combined with an exemplary image and an IFC file of the example object.

Contract

The AIA and BAP contract documents must refer to the provisions of the BIM strategy, as well as to the SOM, GOM, any component library, and all other relevant documents. AIA and BAP should not re-explain items such as AWFs, unless a completely new AWF is defined for the project. In addition, a complete and detailed description of all data to be delivered by the contractor, including delivery dates, is recommended. The workflows for quality control and data acceptance should be standardized for this purpose.

Model-based work

When working with BIM, the model is always at the center of the process (single source of truth). That is why every effort should be made to conduct all processes in a model-based manner, such as meetings, quality checks (collisions, sightlines, attribution), construction scheduling, and the analysis of quantities and costs. In this way, model-based processes can eventually replace conventional deliverables, and end-to-end digital processes can be established.

Since the Federal Ministry of Transport and Digital Infrastructure published the phased plan “Digital Planning and Construction” in 2015, significant efforts have been made to implement it. The goal is to digitize the construction industry and widely implement BIM across all phases of infrastructure construction. As part of the digitalization process, DB InfraGO AG launched the BIM2Build test program, in which various pilot projects tested the use of BIM in the execution phases (LPHs 5 and 8). The data and experience generated were analyzed by the research project of the same name, and conclusions were drawn regarding the standardization of BIM in the construction of infrastructure projects.

As part of the BIM2Build research project, the following was accomplished:

• A qualitative data analysis concept for the use of BIM in the construction phases of infrastructure projects was developed,
• Data was collected, processed, and analyzed for 6 ongoing or completed rail construction projects,
• The projects were compared with one another and with conventional planning methods,
• Conclusions were drawn regarding what worked well (model quality, working with CDEs, construction meetings and clash detection, execution) and what did not (attribution, certain use cases are very time-consuming),
• Optimization potential was identified, and 
• Recommendations for action regarding contractual matters (AIA and BAP), requirements for the client and contractor, BIM use cases, and data transfer to and from other project phases and CDEs were developed.

Based on these results, further steps can now be derived to standardize the use of BIM during the construction phases. Although the results primarily apply to rail construction projects, they can easily be extended to the entire infrastructure sector. Adaptation for building construction is also imaginable.

[1]       Bundesministerium für Verkehr und digitale Infrastruktur, ed., Stufenplan Digitales Planen und Bauen, (2015). bmdv.bund.de/SharedDocs/DE/Publikationen/DG/stufenplan-digitales-bauen.pdf.

[2]       DB InfraGO AG, Geschäftsbereich Personenbahnhöfe, Vorgaben zur Anwendung der BIM-Methodik DB InfraGO AG, (n.d.). infoplattform-personenbahnhoefe.deutschebahn.com/pbhf/DB-BIM/Vorgaben_zur_Anwendung_der_BIM-Methodik-7719352 (accessed May 11, 2026).