Production planning in steel bridge construction: SCHACHTBAU NORDHAUSEN aligns space allocation with production planning

Considering spatial constraints as an additional bottleneck in production control

Production planning in steel bridge construction involves the detailed coordination and organization of individual production processes for steel structures, with a focus on identifying and managing bottlenecks. In addition to sequencing production steps, allocating resources, and ensuring the timely availability of materials, spatial constraints are also taken into account. These constraints may stem from limited space at the production site, the need for specialized lifting and transport equipment, or safety requirements. DUALIS offers a new digital solution for production planning by combining expertise in production scheduling (GANTTPLAN APS) and space allocation (AREAPLAN). This integrated approach is currently being successfully implemented by SCHACHTBAU NORDHAUSEN GmbH.

The GANTTPLAN APS tool schedules resources such as machines, personnel, and production aids against limited capacities. Using advanced planning algorithms, it optimizes various target criteria, such as lead time, deadline adherence, and machine utilization—based on cost considerations. A graphical control panel provides a comprehensive overview of the production schedule. In projects with customers from the mechanical and plant engineering sectors, it has become increasingly clear that the space required for step-by-step assembly is a critical capacity constraint.

This raised the question: How can GANTTPLAN APS be enhanced with efficient production control? And how can spatial factors – such as floor load capacity, available lifting equipment, or utility connections – be integrated into the planning process?

From concept to demonstration model in machine tool manufacturing

Demonstration scenario and planning challenge

To explore this, DUALIS developed a demonstration scenario based on a machine tool manufacturer. To reflect a wide range of space allocation needs during assembly, the demonstration customer was chosen for their diverse product portfolio, which includes everything from small lathes to complex machining cells. A key feature of this scenario is the increasing space requirement as assembly progresses. Once testing is complete, the assembled machine is disassembled into components and shipped to the customer.

Given the assumed average vertical integration, both primary and secondary requirements must be met through a combination of in-house production and external procurement. Assembly takes place in permanently assigned bays, which remain occupied for the entire duration of the process. This results in high capital commitment and extended space usage.

The solution

As is standard practice, all master and transaction data required for planning is stored in an ERP system. GANTTPLAN APS communicates with the demo ERP system via an established interface. To incorporate space capacity constraints, an additional interface was developed for the proven AREAPLAN space management tool. This software determines space requirements and schedules assembly and production projects or large components. It considers spatial constraints such as ceiling height, surface load, and restricted zones, as well as time sequences to reflect ongoing changes or long lead times. In the demonstration scenario, this means that detailed order planning in GANTTPLAN APS includes 100% standardized space allocation per assembly bay.

The layout of the fictional assembly hall was created in AREAPLAN and is now used to plan assembly orders transferred from GANTTPLAN. This adds space allocation and visual tracking of assembly progress to the detailed planning process.

SCHACHTBAU NORDHAUSEN GmbH: From Proof of Concept to Market-Ready Solution

The key driver for real-world development came from a proof of concept (PoC) project at SCHACHTBAU NORDHAUSEN GmbH (SBN), a leading company in mining, plant, steel, and mechanical engineering.

The project focused on the production, pre-assembly, and final assembly of steel components for road and rail bridge construction. These processes are highly space-intensive, with throughput times ranging from several days to weeks—resulting in prolonged occupation of hall sections. Some tasks also require overhead cranes, which are limited in capacity and only available in specific halls.

To meet these demands, in addition to standard ERP master and movement data, CAD data for the assemblies had to be integrated into both GANTTPLAN and AREAPLAN.

The PoC led to the launch of a dedicated implementation project. After initially focusing on assembly planning, additional production stages—such as steel plate cutting and painting—are now being gradually incorporated.

How software-supported production planning works: GANTTPLAN APS leads, AREAPLAN assists

In the interaction between the two tools, GANTTPLAN APS takes the lead. It already features a bidirectional interface with many ERP and MES systems, enabling the transfer of master and transaction data relevant to production planning, as well as real-time shop floor data such as machine utilization and work-in-progress inventory. In this specific customer case, however, no connection to the existing ERP system was desired. Instead, all necessary data was to be provided via Siemens NX.

Together with a service provider commissioned by the customer, the NX data export for the required assembly data was defined and transferred to GANTTPLAN APS via CSV import. Siemens NX also supplies CAD files of the assemblies, which are used directly in AREAPLAN.

Planning is carried out in multiple stages. Initially, GANTTPLAN APS uses current hall utilization data to determine realistic completion dates for individual assemblies and the finished bridge. Siemens NX provides data on assembly weight and dimensions, assembly sequences, personnel requirements, and preferred hall areas. This data is processed in GANTTPLAN to generate bills of materials, routing plans, and production orders. The design department then refines this production data to further detail the planning in GANTTPLAN APS.

The order network is structured so that multiple assembly and processing stages are interlinked, and the transport of assemblies to the bridge construction site is also included in the schedule. During planning, GANTTPLAN APS compares the percentage of space occupied by each assembly with the available hall space, allowing for multiple occupancy of hall sections while considering space as a limiting factor. Personnel availability is another key factor in scheduling.

Once all orders are scheduled in GANTTPLAN APS, the preliminary production plan is transferred to AREAPLAN via a database connection. After import, a visual inspection of the allocated areas over time is conducted, and assemblies are precisely positioned in the hall.

With a single click, assemblies can be imported into AREAPLAN’s 3D environment along with their planning data. If a CAD file is available, the assembly is displayed using that file; otherwise, it is shown as a block model. Outdated assemblies can be automatically removed from the 3D view. If the design department makes changes or if scheduling is updated, notifications are provided.

Since GANTTPLAN APS is not a space planning tool, it only estimates the space occupied by each assembly. This makes the next step critical: If the planner in AREAPLAN determines that an assembly cannot be installed in the designated hall due to spatial or geometric constraints, they can adjust the space allocation. The validated production plan is then sent back to GANTTPLAN APS via the database connection. At this point, the production plan is updated with the AREAPLAN specifications and finalized.

Ideal for manufacturers of large assemblies in (special) machine, plant, and steel construction

The combined use of GANTTPLAN APS and AREAPLAN is particularly well-suited for manufacturers that assemble large, complex products over extended periods – especially when space is a limiting factor. This includes companies in special machinery, plant, and steel construction, as well as those involved in single-unit or small-batch assembly based on the construction site principle. The key benefit of this integration is the ability to simulate multiple spatial and temporal planning scenarios. This increases transparency and flexibility while reducing planning effort.

Extensions for digital assembly and production planning: What’s next?

The current solution focuses on assembly and production processes. Procurement of purchased parts – such as sheet metal panels – is not yet included. However, by integrating an ERP system, the entire process chain could be mapped, from raw material ordering to production preparation and final delivery.

GANTTPLAN can generate order proposals and issue alerts for missing materials. This allows delays in upstream manufacturing stages to be reflected in the assembly schedule – before large components occupy valuable production space. Personnel scheduling can also be managed using GANTTPLAN APS. Relevant data such as shift schedules or special working times can be imported from ERP or dedicated workforce management/time tracking systems (PZE).

Additionally, production data collection (PDC) and feedback to the planning system are highly relevant in special machinery, plant, and steel construction. This enables rapid responses to unplanned disruptions on the shop floor—such as machine breakdowns, missing parts, or quality assurance issues. GANTTPLAN Confirmation, a PDC feature embedded in GANTTPLAN APS, provides real-time feedback on all planning-relevant process steps, including material provisioning, design, and shipping.

Production planning with GANTTPLAN APS and AREAPLAN: A summary

GANTTPLAN APS and the 3D floor planner AREAPLAN are established software solutions from DUALIS GmbH IT Solution. Their combination introduces a new dimension in multi-resource planning: planning against limited spatial capacities. This enables modern, efficient production planning—especially for companies in special machinery, plant, and steel construction, as well as those involved in individual and small-batch production.

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