Measurement technology in railway engineering

Independent testing laboratory

DB Systemtechnik in Minden offers a wide range of engineering services for the rail engineering industry. The division the will operate independently as a wholly owned subsidiary of DB AG from mid 2011, has its main facilities in Minden, Munich and Kirchmöser and employs around 600 staff who make their expertise in the area of railway technology available both to Deutsche Bahn AG internally and external customers. Many years of experience and unparalleled system know-how have made DB Systemtechnik Europe's leading competence center for the rail engineering industry. DB Systemtechnik performs a wide range of vehicle and component tests in the business segment of approval management, testing and certification; these tests make an important contribution to safe, reliable and efficient rail operations. The DB Systemtechnik test center and expert organization are registered as an associated partner of the Notified Body for interoperability (Assoziierter Partner der benannten Stelle Interoperabilität) at the German Federal Railway Authority (EBA). The total of 18 testing laboratories has been accredited per DIN EN ISO/IEC 17025:2000. About 40 members of staff have been appointed as certified experts by the German Federal Railway Authority.

Extensive technology for a complete Dynotrain measuring train

The vehicles under test within the scope of the Dynotrain project included a locomotive, three freight cars and one passenger car, complemented by the DB Netz AG Railab for recording of the track geometry and by a measuring car accommodating the central measurement technology components and the measurement team. These cars were coupled with six additional cars to ensure correct braking behavior. This train configuration - complemented by a traction locomotive for the respective power networks in Switzerland, France and Italy - was up to 400 m long. Ten of the above described measuring wheelsets were used in the five measuring cars. Over 300 physical channels needed to be recorded and, because of partly differing filter configurations, about 1,000 measurement channels needed to be saved together with all acceleration and displacement signals, track geometry signals and additional information about temperature, air pressure and humidity, GPS data and braking pressure. This places tremendous demands on the measurement system, taking into account the sampling rates of up to 1,200 Hz. In the process, part of the CPU load is already being swapped out. Each of the five measuring wheelset computers computes the total of 48 strain gage full bridge signals provided by two measuring wheelsets up to 1,000 times per second providing the wheel-rail forces that are digitally transferred to the MGC amplifier. The complex fiber-optic network of insularly installed MGC amplifiers and measuring wheelset computers as well as powerful mainframe computers and memories has been specifically designed to withstand such loads. Measurement-data statistics are determined online and can be visualized and subsequently analyzed immediately upon completion of the measurement run. Online recorders visualize part of the raw data to enable the engineer on board to monitor limit values in critical situations. Far more than 3,000 GByte of measurement data have been acquired and saved over about four weeks of measurement runs. They are presently available to the project partners via a fast server connection. A total of seven MGC amplifier systems was used; they are outstanding for their high flexibility and ease of use. The MGCplus system is suited to many different measurement tasks thanks to its modular structure. Corresponding modules are available from stock for virtually all common transducer types. The Transducer Electronic Data Sheet (TEDS) enables a measurement system to be quickly and easily configured. The amplifiers automatically identify the transducers that are connected; no complex manual configuration is required.
Another advantage of the MGCplus system was of importance to its use in the DB Systemtechnik measuring train: All channels of a measurement system can be recorded absolutely synchronously. This is particularly important in this application, because all measured quantities need to be correlated in subsequent analyses. The stage of data analysis has now begun and will require ongoing commitment on the part of the project partners for two to three years. The data obtained from this project will form a basis for vehicle development, design and approval as well as subsequent research projects for many years.