The HOAI divides every planning and construction project into nine service phases. Even though the fee level has no longer been binding since 2021, this structure remains the common vocabulary of planning, execution and supervision.
What the HOAI governs
The Fee Structure for Architects and Engineers (HOAI) is a German regulation that divides planning and supervision services in construction into nine service phases that build on one another, each with its own tasks and results, from the first basic evaluation to the care of the finished structure.
Since 2021 the level of the fees is no longer binding. The content structure of the service phases has remained, however, and continues to serve as a proven, practical framework for planning, execution and billing, especially on complex infrastructure projects.
The nine service phases
Phases 1 to 5 are planning phases; phases 6 to 9 accompany the execution:
- SP 1 Basic evaluation: clarify the task, capture the framework conditions.
- SP 2 Preliminary planning: first solution concepts and comparison of variants.
- SP 3 Design planning: the viable overall concept.
- SP 4 Approval planning: documents for the official procedure.
- SP 5 Implementation planning: the ready-to-build detailed drawings.
- SP 6 Preparation of contract award: bills of quantities and quantities.
- SP 7 Participation in contract award: review tenders, prepare the award.
- SP 8 Site supervision: the supervision of the construction work.
- SP 9 Site care: support after completion, defect tracking.
Service phase 8: site supervision
Site supervision in service phase 8 is the technical supervision of the construction work for conformity with the planning, the permit and the recognised rules of technology. This is where it is decided whether good plans become a defect-free structure: quality, costs and deadlines are monitored, documented and steered.
In railway construction this very phase takes on its particular form. General site supervision becomes railway construction supervision, supplemented by person-bound safety and authorisation tasks and by responsibility for live operations.
The railway angle
Whereas in building construction site supervision primarily safeguards quality and deadlines, in railway construction the safety of a transport system that keeps running is added. Supervision must keep construction phases, the Betra, the switching states of the overhead line and the interfaces to signalling and control technology in view.
Where projects fail at the phase transitions
The greatest risks rarely lie within a phase but at the transitions. If the implementation planning (SP 5) is not handed over cleanly to site supervision (SP 8), important provisions are missing on site. If the approval planning (SP 4) is treated too briefly, the procedure catches up with the project later.
In railway construction this is intensified because operational interfaces such as closure windows and commissioning windows must be planned in early. Support that takes responsibility for several phases from one source holds this knowledge together across the transitions and prevents having to start from scratch at every interface.
The phases in a typical railway project
In the basic evaluation and preliminary planning (SP 1 and 2) the need is clarified and the solution space mapped out. In railway construction, first considerations on construction phases and available closure windows already belong here, because they determine what is feasible at all.
The design and approval planning (SP 3 and 4) is often the critical path on railway projects. Approval or plan-approval procedures take time, and errors or gaps in this phase delay the entire project, regardless of how well the work is built later.
With the implementation planning and contract award (SP 5 to 7), the ready-to-build documents and the contractual basis are created. This is where it is decided whether site supervision can later draw on complete, contradiction-free plans.
In site supervision (SP 8), railway construction supervision here, construction and supervision take place until the installation goes into operation via commissioning. Site care (SP 9) follows with defect tracking and documentation.
Häufige Fragen
How many HOAI service phases are there?
Nine. Phases 1 to 5 are planning phases, phases 6 to 9 accompany the execution, including site supervision in phase 8.
Is the HOAI still binding?
The fee level has no longer been binding since 2021. The structure of the nine service phases remains authoritative as a technical framework.
What is site supervision?
Service phase 8: the supervision of construction work for conformity with the planning, the permit and the recognised rules of technology. In railway construction it corresponds to railway construction supervision.
Edoé Lassey
Edoé Lassey führt die LND Ingenieure GmbH als Bauüberwacher und Ingenieur für Infrastruktur- und Tiefbau. Die zertifizierten Rollen Technischer Berechtigter, Sicherungsüberwacher, Schaltantragsteller und Bauvorlageberechtigung gehören zum Leistungskern.
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