Car manufacturer: Roundabout reaches its limits as factory traffic increases
Software: AnyLogic
An automotive manufacturer with a plant in Hungary uses a roundabout directly outside the factory gates, which handles both daily staff traffic and logistics traffic involving lorries. As the plant anticipated rising vehicle volumes, the automotive manufacturer wanted to know in advance whether the roundabout could still cope with this additional load.
Initial situation: A roundabout with several critical points
The roundabout connects several access roads to the plant and must therefore accommodate very different types of traffic simultaneously. One access road led via a narrow, sharp bend that lorries could only negotiate in a single lane, so it was unclear how well heavy goods traffic could still be managed there. It was also difficult to assess the general driving and braking behaviour of vehicles within the roundabout itself without a reliable data set.
As the project also involved a significant amount of coordination with the Hungarian authorities, documents had to be translated between Hungarian and German. Furthermore, the assessment of traffic flow had to comply with Hungarian quality standards. The car manufacturer therefore opted for a simulation to provide a sound basis for deciding on possible measures, rather than relying solely on estimates.
Objective: To identify capacity limits at an early stage
The simulation was intended to answer the following questions:
- Can the forecast traffic volumes at the roundabout be managed at all?
- When do traffic jams and delays occur during peak times?
- How can potential optimisation measures be tested risk-free before they are actually implemented?
- Which key performance indicators support the decision to implement them?
Solution: Traffic simulation with AnyLogic
SimPlan used AnyLogic to build a simulation model of the roundabout and the adjacent roads. The model incorporated both logistics traffic (lorries) and staff traffic, as both types of traffic share the roundabout. As the sharp bend was particularly critical for heavy goods vehicles, the model also depicted in detail the vehicles’ driving and braking behaviour within the roundabout.
On this basis, SimPlan tested how traffic behaves as volumes gradually increase compared with existing plant traffic. This made it possible to determine the traffic volume at which the roundabout still functions and the point at which disruptions occur, without the need for a real-world test run.
Results: Clear capacity limit confirmed
The simulation provided concrete figures for the roundabout’s capacity:
- Traffic continued to flow freely up to a 40 per cent increase compared with existing plant traffic.
- From 50 per cent additional traffic onwards, noticeable queues and disruptions began to occur.
- From 80 per cent, there were long delays, culminating in a complete breakdown of traffic flow.
The simulation thus demonstrated that the roundabout alone is not sufficient to cope with a further increase in lorry capacity. This provided the car manufacturer with a robust basis for deciding on further measures, as without the simulation it would have been very difficult to assess this risk.
Why factory access roads quickly become bottlenecks
This case study illustrates how closely logistics and infrastructure are interlinked. If traffic increases at a single access point, this immediately affects all plant traffic, as staff and logistics share the same bottleneck. By simulating such capacity limits in advance, organisations can avoid wrong decisions and target investments precisely where they will actually have an impact. This applies not only to car manufacturers, but to any production site where growing plant traffic meets limited transport infrastructure.
