Two rolling-stock/infrastructure mechanical interfaces are present in the railways. The first consists of wheel/rail contact, which has been a topic of research for many years, concerning safety and comfort, from the modelling and experimental point of views. The second consists of the pantograph/catenary contact, in which much less research has been performed. However, the pantograph-catenary interface represents one of the most critical interfaces.
From a scientific point of view, the pantograph-catenary interaction generally constitutes of the first blocking point when increasing train speed, due to the phenomenon known as the 'catenary barrier' - in reference to the sound barrier - which refers to the fact that when the train speed reaches the propagation speed of the flexural waves in the contact wire a singularity emerges, creating particularly high level of fluctuations in the contact wire. When operating in a multiple unit configuration, the pantograph-catenary system is even more critical, since the second pantograph experiences a catenary that is already perturbed by the passage of the first pantograph.
From a more practical point of view, this interface implies interoperability issues, contrary to the wheel/rail contact. Finally, defects in the catenary or in the pantograph often lead to the rupture of the contact wire and consequently to the interruption of service on the line and to perturbation on the adjacent lines. Statistics consolidated over Europe show an average number of approximately one million minutes of delay related to current collection, generating tremendous costs to the railway stakeholders in particular and to the society in general.
The project aimed at enhancing interoperability between pantographs and catenaries all over Europe, decreasing the number of incidents related to this system, and reducing maintenance costs through improving preventive maintenance and diminishing corrective maintenance.
The Europac objectives were:
- to bring together European manufacturers, operators, infrastructure managers and academia involved in railway activities to build up a common research project that will significantly contribute to reinforcing interoperability and standardisation throughout the European rail community;
- to develop a joint numerical software to model the dynamic behaviour of the pantograph-catenary system in three-dimensions, designed to be capable of simulating all present and future infrastructure and rolling stock configurations;
- to assess existing, and specify new, technical specifications for interoperability;
- to study and model the impact of deteriorated conditions on the pantograph-catenary system’s behaviour including crosswinds and extreme temperature situations, material defects and wear;
- to develop a prototype of a trackside monitoring station aimed at detecting, identifying and assessing, in real-time, defects in a pantograph coming into a network;
- to develop a prototype of an onboard monitoring system designed to detect, identify and assess defects in a catenary in real-time.
Interoperability covers two main issues: ensuring interoperability of the equipment during the development phase and monitoring interoperability during operation. Maintenance can also be improved through simulating deteriorated conditions and monitoring systems. To address these two aspects, Europac produced two types of tools: software and monitoring systems.
Two work packages were dedicated to the development of the Europac joint software. The first was focused on the design of joint nominal software aimed at being capable of representing all current and future pantographs and catenaries. The second was designed to complete the software with modules representing the effects of deteriorated conditions: extreme climatic conditions, defect and wear effects.
Operational interoperability and maintenance were ensured by the monitoring systems developed within two other work packages. For this purpose, these work packages were for the development of a new generation of monitoring systems combining expert systems and machine efficiency. Moreover, these monitoring systems took advantage of the defect signatures provided by the software, not only to detect the defect effects but also to identify their origin and assess their seriousness. Inversely, the software could be validated and refined if necessary using results measured by the monitoring systems.
The project Work-Packages were as follows:
- WP1 was dedicated to the development of EUROPACAS;
- WP2 consisted of studying, the deteriorated situations using EUROPACAS;
- WP3 developed the track-side monitoring station;
- WP4 consisted of developing the onboard monitoring system.
These work packages strongly interacted with each other. Indeed, WP1 and WP2 both contributed to the development of the joint software that would help assessing interoperability and studying deteriorated situations, thanks to its flexibility and to its 3D feature. This software provided the measurement systems with the physical understanding of the pantograph-catenary dynamics and with defects signatures used to teach the expert systems. Inversely, WP3 and WP4 supported validating and refining EUROPACAS.
The first result of EUROPAC is a joint interoperable software, which simulates the pantograph catenary dynamic interaction. It is made of two independent softwares which are based on the most up-to-date scientific knowledge. The first module 'Outil de simulation du captage pour la reconnaissance des défauts' (OSCAR) developed by SNCF simulates the catenary and the second one, 'Dynamic analysis program (DAP) developed by IST simulates the pantograph. The resulting tool, named Europacas allows simulating any type of pantographs and catenaries in three dimensions, and allows taking into account up to now unaddressed effects such as the action of wind, temperature, switches, road bridges, etc.
The second main outcome of EUROPAC is a track-side monitoring station, which is in operation along a high-speed line in Germany. It is based on already existing sensors such as uplift and acceleration sensors, mounted on the contact wire. Coupled with a real-time diagnosis tool, which analyses the measured signals in an automatic way, it allows detecting and identifying defects in the pantographs passing on the line.
Last but not least, EUROPAC resulted in an on-board monitoring system which automatically inspects, at high-speed, the state of the catenary. Based on 'classical' sensors such as accelerometers and force sensors mounted on a pantograph, it is completed with an expert system combining human-like expertise and automation, named the 'Real-time data analyser' (RTDA). This RTDA analyses the signals in real-time, and consequently detects, localises and identifies the defects present in the catenary system.