Reducing walking distances by up to 70 percent while balancing workloads to reduce strain on the staff

Reducing physical strain

Employees handle thousands of shipments every day in parcel hubs, often under significant physical strain. At Graz University of Technology (TU Graz), Prof. Dr. Domenik Kaever, university professor and head of the Institute of Logistics Engineering, and his team set out to determine how these strains could be significantly reduced by using Plant Simulation in the Tecnomatix® portfolio and Simcenter™ HEEDS™ software. They are both part of the Siemens Xcelerator business platform of software, hardware and services.

“The combination of discrete event simulation with Plant Simulation and multi-objective optimization with Simcenter HEEDS is a powerful software combination for optimizing highly complex systems with many competing constraints and variables,” says Kaever.

At the Institute of Logistics Engineering, research teams combine advanced simulation technology with practical testing. Material handling and storage systems are first developed in a virtual environment and tested in state-of-the-art logistics laboratories. The institute’s expertise covers virtual engineering, digital twin applications and adaptive material flow systems. By collaborating closely with industrial partners worldwide, Graz ensures that research findings are quickly applied to real projects, helping to shape the future of logistics solutions.

Optimization meets simulation

Simcenter HEEDS is a solution for automated design space exploration. It is used to systematically change model input parameters, run simulations and identify solutions that meet defined performance requirements. When it is used in combination with Plant Simulation, it becomes an even more powerful tool. Using Plant Simulation enables TU Graz to build detailed digital models of complex material flow and production systems, while Simcenter HEEDS searches these models for the best configurations. Especially when there are multiple objectives and constraints, using the Simcenter HEEDS multi-objective optimization capabilities is a good choice for finding balanced solutions.

Both solutions are part of the Siemens Industrial Metaverse, which help make simulations more comprehensive, effective and reliable, from initial design through virtual commissioning.

“With the combination of Plant Simulation and Simcenter HEEDS, we demonstrated that ergonomic improvements and operational targets are not mutually exclusive,” says Kaever.

“Even with stable throughput, we were able to significantly reduce walking distances and physical strain for employees. This is an important step toward practical solutions that measurably improve daily working conditions.”

Outbound area of parcel logistics hub modeled in Plant Simulation.

Key nodes in the parcel network

Parcel hubs are essential nodes in logistics networks. They are used to consolidate incoming shipments from various regions, sort them and send them to the next stations in the distribution chain. Operations typically follow a set sequence: inbound shipments are unloaded and staged for identification, scanned, often via barcode or radio frequency identification (RFID), and routed through sorting systems to their destinations.

Five core areas

A typical parcel hub consists of:

1. Inbound area – unloading and receipt of shipments.
2. Preparation – presorting and staging for identification.
3. Identification – capturing shipment data.
4. Sorting – assigning shipments to outbound destinations.
5. Outbound area – loading for onward transport.

Each of these areas is closely interconnected. A slowdown in one part quickly affects the rest of the operation and the workload of the staff.

The virtual parcel hub

Using Plant Simulation, the Institute of Logistics Engineering created a complete, detailed digital model of a parcel hub. This “Virtual Parcel Hub” replicates every process step from inbound to outbound with realistic accuracy. It serves as a shared foundation for teaching and research, enabling the analysis of workflows, the testing of new technologies and the safe evaluation of potential improvements. Extended reality applications complement the model, allowing work steps to be experienced in an immersive way, and proposed changes to be assessed before implementation.

Virtual Parcel Hub modeled in Plant Simulation.

Making workloads visible

One current research focus examines working conditions in parcel hubs. Employees move thousands of shipments per day under increasing time pressure. Differences in package size and weight make lifting, carrying and sorting more challenging. Long walking distances and unevenly distributed tasks further increase physical strain.

What determines the workload

Before modeling began, the Institute of Logistics Engineering analyzed the main factors influencing working conditions in parcel hubs. These included process design, shipment characteristics, facility layout and equipment, as well as individual worker attributes. All these factors can be modeled to create an accurate picture of real-world strain and provide a reliable basis for evaluating improvements.

Baseline scenario

The study used a simplified yet realistic parcel hub scenario. In the outbound area, four employees handled the sorting process, with each responsible for 10 of 40 chutes. Shifts lasted eight hours without scheduled breaks. Shipments traveled at 2.7 meters per second and were randomly assigned to chutes based on postal codes.

The model reproduced typical working conditions. After emptying a chute, each worker moved to the next one in their zone that contained shipments. The simulation tracked the number and weight of handled shipments as well as walking distances. In this baseline setup, workload imbalances and walking distances were evident.

Human-centered optimization

The digital model incorporated operational metrics such as throughput and error rates alongside ergonomic indicators like frequency of lifts and walking distances. Treating these as equally important made it possible to identify configurations that met operational targets while reducing physical strain on employees.

Metrics from two worlds

The analysis linked ergonomic and operational metrics in a single framework. On one side were the frequency of lifts and walking distances. On the other were throughput, error rates and processing times. This combination made it possible to identify solutions that supported both employee well-being and system performance.

Example of a downsized outbound area of parcel logistics hub modeled in Plant Simulation.

Balanced results

This approach avoided optimizations focused solely on efficiency or exclusively on ergonomics. Simcenter HEEDS automatically explored and identified configurations that delivered strong results in both areas.

Step 1 – reducing walking distances

The first optimization targeted walking distances. A new routing logic instructed workers to wait until a chute reached a certain fill level before going there, preventing unnecessary trips to half-empty chutes. Throughput remained stable while average walking distances dropped by almost 10 percent in one scenario and up to 70 percent in another. The results confirmed that identical shipment volumes can be handled with significantly different walking distances, and that Simcenter HEEDS can be used to pinpoint the most efficient patterns.

Step 2 – balancing workloads

The second optimization involved reassigning postal codes to chutes to balance the number and weight of shipments handled by each worker. With 40 chutes, there are 40 factorial possible assignments, far too many to evaluate manually. This is where Simcenter HEEDS proved invaluable, automatically assessing large numbers of combinations to identify the most effective options. The optimization reduced both walking distances and handled mass per person without noticeably affecting throughput.

From simulation to real operations

The findings can be applied directly to real parcel hubs, guiding targeted adjustments to processes and layouts. Measuring both ergonomic and operational effects enables operators to make informed decisions before implementing costly physical changes.

Data analysis provides more insight

The next step will be to capture real operational data and integrate it with simulation results. Motion analysis using sensors or wearable devices can provide valuable insight into actual walking paths, workload peaks and ergonomic risk factors. Feeding this data into Plant Simulation allows for even more accurate models and targeted optimizations.

Outlook

The current results are based on simulated scenarios and will be validated with real operational data. The potential is clear: digital models like the Virtual Parcel Hub can quantify workloads, support targeted optimizations and align productivity with employee well-being.

Plans include integrating further human-centered factors such as stress levels and physical condition. Linking these with methods like data mining will bring virtual analysis even closer to real-world conditions. One long-term vision is to create a digital society in Plant Simulation to better understand complex social and ergonomic interactions.

With Plant Simulation and Simcenter HEEDS, organizations have tools embedded in the Siemens Industrial Metaverse, which provides access to a wide range of technologies and data sources. This foundation can help make parcel hubs, as well as other intralogistics systems, more efficient and more user-friendly.

Prof. Dr. Domenik Kaever, university professor and Head of the Institute of Logistics Engineering at Graz University of Technology.