Technology for maintenance works

The increasing change in traffic towards rail, the opening of the market in European railway traffic and the increasing responsibility for providers of railways make heavy demands on the quality and the availability of the rail infrastructure.

Effective and efficient maintenance concepts are sought after more than ever. New ways, innovative processes and technical solutions are the focal point of the current development and define its aim and purpose, because the operators of the railway infrastructure expect the providers of the railway infrastructure to offer attractive, sophisticated concepts and maintenance procedures.

Since 2005, DB Netz AG has implemented a special sustainability programme for maintenance services in Germany comprising primarily the measures for the mechanised maintenance and reprofiling of tracks and switches. Factors for success and conditions for the optimal utilisation of the resources are, on one hand, the precise planning of measures (e.g. lines defined with kilometer accuracy, large uninterrupted sections) and the optimal use of the periods of track possession on the other. For railway infrastructure providers like the Bahnbau Group, this means developing and using innovative technologies adapted to the current requirements. The Bahnbau Group, consisting of the DB Bahnbau GmbH, the Deutsche Bahn Gleisbau GmbH, the Deutsche Gleis- und Tiefbau GmbH, the Mobile Oberbauschweißtechnik GmbH and the Ingenieur-, Brücken- und Tiefbau GmbH takes up this challenge.

The Bahnbau Group is the integrated railway infrastructure provider for innovative and customer-oriented construction and erection services for the routes of the European railways. The companies of the Bahnbau Group are subsidiaries of the DB Netz AG. They offer high-quality services in the fields of planning, new building and rebuilding, assembly and maintenance from underground drainage systems up to overhead-line systems. The Bahnbau Group has special know-how in the overall and comprehensive project management and offers services as general contractor. The company is a competent partner of DB Netz AG in all essential fields of activities in renewal and maintenance programmes. The knowledge gained by many years experience is being implemented successfully for third parties both nationally and internationally.

The investments into a modern machinery pool have proven to be a decisive factor for the successful and efficient execution of building projects especially for maintenance, new building and rebuilding of tracks and switches. With its specific and unique machinery pool of Europe, the Bahnbau Group is able to meet the high demands of the railway infrastructure operators in respect of quality and efficiency. More than 100 machines, among them large permanent-way machines for ballast cleaning, relaying machinery, surveying and tamping machinery, milling and grinding machinery, overhead line assembly vehicles and traction units allow the independent execution of building projects even in peak periods. For instance, one of the most innovative and economic solutions in rail machining is the rail milling and grinding train SF 03-FFS; the SUZ 500 UVR is presently one of the most efficient machines in the world for building new tracks, track relaying and dismantling. The purpose of this technical development is to carry out the track works as efficiently as possible and thus to reduce the interruptions of train operations.

One step to a perfect rail profile in the track

The fact that the service life of the total track structure is directly influenced by the quality of the rail surface has led to the development of new technologies for rail profiling. Rail maintenance should become faster, more efficient and favourably priced. Since the end of 2004, the high-capacity rail milling and grinding machine of type SF 03-FFS developed by the Bahnbau Group and the Linsinger company has set new standards in Germany – rail milling and grinding in one pass.

The new rail profiling technology SF 03-FFS combining milling and grinding in one pass exceeds the traditional method of repair and maintenance requirements. The system consists of two main components – 2×2 milling heads running synchronously and two peripheral grinding wheels running in longitudinal direction. The milling unit is used to re-establish the desired rail head section. Re-profiling, milling of new rails and gear correction are possible by means of the SF 03-FFS. The milling depth ranges from 0.1 to 3.0 mm. Subject to the condition of the track structure and the milling depth, a machining speed of up to 1,200 m per hour may be achieved. Sometimes, however, in track maintenance the milling depth amounts to 5.0 mm. The practical mean machining speed is 750 track m per hour.

State of the art machines guarantee a high degree of accuracy. High-capacity processors control the grinding and milling heads and hold them within a tolerance of 0.01 mm. This reliability and surface accuracy contribute considerably to a smoother and noise-reduced train operation as well as to lower wear and tear of the rails and wheels. Additionally, the milling and grinding process and the removal of rail defects (among others head checks, squats, Belgrospis) extend the service life of the rails and have a positive influence on the equivalent taper.

Due to the new technology the usual flying sparks and fire danger are excluded. Special suction equipment catches the sparks and the grinding dust directly above the tools and carries them to an intercepting tank in the SF 03-FFS.

Relaying, tamping and surveying methods

State of the art technologies and machinery are sought-after for repair, new building and re-building of tracks and switches in the rail net. In this connection, too, the Bahnbau Group made use of the know-how of their engineers and machine specialists in order to strengthen their pioneering role. So the Bahnbau Group uses for example the high-speed relaying train SUZ 500 UVR from Plasser&Theurer. It allows us to rebuild, to lay and to remove tracks using the assembly line technique without closing the adjacent track. This method suits all common types of sleeper –concrete, steel, wooden or Y sleepers.

Efficiency is also increased by the state-of-the-art tamping and surveying machinery. So the Bahnbau Group applies the tamping as well as the universal tamping machinery. By means of the tamping express really continuous three-sleeper tamping is carried out. The universal tamping machines are used to carry out maintenance works in turnout areas. The maintenance of turnouts is carried out with three-rail lifting and four-rail tamping. Due to the telescopic arm the outer tamping units may be used for tamping the fourth rail. The track survey car EM-Sat 120 does the mechanised track surveying for track maintenance and rebuilding. By means of fixed-point surveying devices the absolute track geometry is measured. The values for track correction may be transmitted to the tamping machinery by means of disks.

Conclusion

The experience in Germany has shown that the present challenges and the requirements for efficient track work can be mastered with the help of state-of-the-art technologies and machines. The investments into the most modern machinery have led to a significant increase of the efficiency. The utilisation of the machines in Germany has basically shown positive results, so that in the future more emphasis is placed on their additional use abroad, especially in European countries like Italy, Spain, Great Britain or Scandinavia. The machines are designed in such a way that they meet the European requirements. In the end, the higher quality is not only to the benefit of the railway infrastructure operators but also to the benefit of its users.