today 144
today 144
The Dynamic Track Stabilizer (DGS) has been delivering greater safety, higher availability, and more efficient operations in track construction and maintenance for half a century. What began as a technological response to reduced track stability after construction and maintenance has since turned into an indispensable standard procedure in modern track work.
Certain track construction and maintenance activities reduce the resistance of the ballast bed against lateral displacement of the track panel, also known as lateral track resistance (LTR). Dynamic track stabilization makes it possible to restore this to the required level. It eliminates or reduces the need for low-speed sections, and allows busy lines to be back in operation under full-speed traffic faster and more sustainably. As we mark the 50th anniversary of this key technology, we take a look at how it was developed, how it has helped improve the performance of the rail system, and the potential it still holds for the future.
The construction and maintenance of heavily utilized lines are now barely imaginable without dynamic track stabilization. By providing perfectly prepared lines, this method has also played a part in achieving world speed records. The technology has developed constantly over time thanks to years of research and comprehensive experience in the field.
50 years old and more relevant than ever
The increasing requirements on modern railway systems demand high availability alongside precise and durable track stability. The main prerequisites here are a well-compacted ballast bed and high lateral track resistance. This is because on a continuously welded track, the stresses caused by temperature-related expansions and contractions are diverted through the track panel into the ballast. The LTR must be sufficient to allow this release of tension without the track panel unintentionally buckling, leading to a track distortion. Renewal or maintenance work that affects the ballast bed significantly reduces the LTR. As a result, various methods of restoring it were developed and trialled.
The targeted use of vibrations perpendicular to the track centreline was a major technological breakthrough that ultimately led to the development of dynamic track stabilization. By rearranging and compacting the ballast grains with virtually no applied force, this creates a homogeneous structure in the ballast bed that delivers durable stability.
Tamping machines are effective at reproducing the track geometry, but this process weakens the embedding of the track panel in the ballast bed. The Dynamic Track Stabilizer was developed with the aim of reinforcing track stability, in order to secure the position of the track for the long term and ensure safe railway operations. 50 years and countless deployments later, this machine has successfully accomplished its mission.
Klaus Riessberger (Professor emeritus, TU Graz)
Played a key role in the development of dynamic track stabilization.
Plasser & Theurer has been developing and producing Dynamic Track Stabilizers (DGS) since 1973. The first operational machine was presented at the VDEI conference (now the iaf) in Frankfurt in 1975. Sales to our customers began one year later in 1976, now 50 years ago.
Within just a few years of its launch, the Dynamic Track Stabilizer established itself as an essential tool in track construction and maintenance. More than 1,300 machines have since been supplied to 60 countries. Today, this technology is an integral part of modern construction and maintenance activities.
The variants on offer now include the Plasser TrackStabilizer, Plasser CompactStabilizer, and the two-axle Plasser StabilizingTrailer. Technological progress has also made it possible to integrate track stabilizing units in other machine systems. These stabilizing units can now be found in track renewal machines, ballast bed cleaning machines, or tamping machines, for example.
From research to a global technological cornerstone
Decades of development work, paired with close and continuous collaboration with countless railway infrastructure companies around the world, have created a wealth of knowledge in this area regarding both the technology and its applications.
The main foundations for this were provided by a series of tests performed by the company’s own R&D department, as well as the cooperation with TU Graz. This determined the optimum parameters such as imposed load, frequency, effect duration, and amplitude. These tests showed that compacting the ballast with horizontal vibrations could be up to seven times more efficient than vertical vibrations.
Although the technology was first launched 50 years ago, the constant research and sophisticated testing, simulations, and DEM (discrete element method) have further optimized the technology and parameters.
From work tool to measuring instrument
The results of recent research with TU Munich and TU Vienna have shown how the modern ballasted track will continue to benefit from dynamic track stabilization in future. Increasing loads, ever shorter track possessions, and the desire for longer maintenance intervals will inspire further innovations.
As with tamping machines that record data about the condition of the infrastructure during track maintenance, current efforts around the DGS now focus on collecting valuable information about the condition of the infrastructure during operations, and further boosting the efficiency of track maintenance. Innovative sensors are enabling this proven stabilization technology to provide all-new insights into the track condition. Researchers are analysing measurement values from the machine-ballast interaction and determining parameters describing the condition of the rail fastening or ballast bed.
The new DGS prototype enables continuous measurement of the horizontal track stiffness. This information could go on to form the basis of acceptance testing in future. LTR data will remain as additional control and reference measurements at specific points.
New design measures are leading to further improvements in ballast stabilization. Dynamic decoupling allows vibrations to be diverted into the superstructure more efficiently and reduces machine wear. Lowering the point at which the impact force is applied improves the horizontal pulse transmission to the sleepers. Changing to electric drive systems further improves efficiency, while supplying energy via the overhead contact line enables carbon-neutral operation, depending on the way the traction current is generated. The DGS will therefore remain a key element of maintenance strategies going forward, and will build upon its role as a control instrument.
