As part of the preparations and impact assessment for the next legislative framework governing European partnerships...
Public Consultation: Shape the future of European partnerships
read more
Independently Rotating, Directly Driven Wheels Running Gear
Challenge
European rail systems face increasing pressure to reduce operational and maintenance costs while improving availability and reliability. Conventional running gear architectures generate significant wheel and rail wear, leading to frequent maintenance interventions, higher lifecycle costs, and increased resource consumption.
The solution
The Independently Rotating and Directly Driven Wheels Running Gear (IRDW) introduces a novel railway running gear architecture in which each wheel is individually actuated and actively controlled, eliminating the need for a conventional solid axle. This enables precise control of wheel–rail interaction, allowing the lateral position of each wheelset to be adjusted with high accuracy.
By replacing passive mechanical guidance with an actively controlled mechatronic system, IRDW significantly reduces wheel and rail wear, minimises noise emissions, and enhances ride comfort. The system integrates advanced sensing, dynamic modelling, and control algorithms to ensure stable operation under varying conditions, including nonlinear effects such as hysteresis and variable damping.
In addition, the architecture enables lightweight design and increased flexibility in vehicle layout, while embedded sensors provide valuable data for condition monitoring of both the vehicle and the track. Overall, IRDW represents a key enabling technology for intelligent, efficient, and low-maintenance railway systems.
Readiness for Industrialisation and Deployment
The IRDW running gear is currently in an advanced prototype and validation phase, supported by extensive multi-body simulation and digital modelling capabilities for wear prediction, curve behaviour and dynamic system performance.
A 1:5 scale test rig has been in operation for an extended period and has already been used to validate and refine key control algorithms, particularly with respect to wear minimisation, stability, and energy-efficient wheel–rail interaction.
A full-scale 1:1 test rig has recently been commissioned and is currently undergoing initial operational use. The system is being actively controlled and tested at low speeds up to approximately 20 km/h, enabling initial validation of system behaviour under realistic mechanical loads and control conditions.
The next development step foresees the transfer of the system to an external high-performance test facility by the end of 2027, where it will be operated at speeds of up to 100 km/h, enabling extended validation under more demanding dynamic conditions. This will be followed by a further scaling of testing capability towards high-speed operation up to 300 km/h.
In parallel, long-term plans include on-track demonstration in real railway environments, supporting full system validation under operational conditions and accelerating the path towards industrial deployment.
Maturity level
TRL 6
Expected benefits
- Lower wear and maintenance costs: achieved through more precise guidance of individual wheels and optimised force distribution. This directly reduces maintenance requirements, extends component lifetimes, and reduces lifecycle expenditure for both rolling stock and infrastructure.
- Improved energy efficiency: supported by reduced mechanical losses and the potential for lightweight design architectures. This contributes to lower operational energy demand and improved environmental performance.
- Enhanced ride performance: active control optimises wheel–rail contact conditions in real time, particularly in curved track sections. This can enable higher permissible speeds or improved comfort at existing speed levels.
- Flexible vehicle design: the removal of conventional axle constraints enables new interior layout freedoms for rolling stock design, including lower and more continuous floor concepts, improving accessibility and passenger capacity utilisation.
- Intelligent Monitoring & Digital Operations: the integration of sensor systems and control intelligence enables condition monitoring and infrastructure data acquisition, creating additional value for predictive maintenance strategies and digital rail operations.
- Market relevance and application potential: the technology addresses key industry drivers such as cost reduction, decarbonisation and capacity optimisation. Its adoption potential spans both passenger and freight applications, particularly in segments where maintenance intensity, speed requirements, and operational efficiency are critical economic factors.
- Lifecycle cost optimisation: the increased system complexity, particularly stemming from the individually driven wheel architecture, additional actuation elements, and integrated control and sensor systems, is expected to result in higher manufacturing costs. However, these upfront investments are expected to be offset over the lifecycle of the system through significantly reduced maintenance requirements. Lower wear rates on both wheel and rail components, combined with improved condition monitoring and targeted maintenance strategies, should lead to fewer service interventions, reduced downtime, and extended component lifetimes. As a result, the total cost of ownership is expected to decrease despite the higher initial production expenditure.
Who benefits
Infrastructure Managers
Railway operators
Suppliers
Final users
Conclusion
The IRDW running gear solution introduces a new railway architecture by combining independently rotating, directly driven wheels with advanced mechatronic control, enabling precise wheel–rail management and improved dynamic performance.
By reducing wear, noise emissions, and lifecycle costs while enhancing energy efficiency, monitoring capabilities, and design flexibility, the technology supports longer component lifetimes and optimized maintenance strategies. Its adaptability across different railway applications and potential to enable new vehicle concepts position IRDW as a key technology for future intelligent, high-performance, and sustainable rail systems.
Learn more about the project
FP4-Rail4Earth
This solution has been developed within the Europe’s Rail (EU-Rail) Flagship Project FP4-Rail4Earth. The project aims to is to improve the existing sustainability performance of railways, to build a more attractive and resilient transport mode and to contribute towards the objectives of a climate neutral Europe for 2050.