Perfecting track maintenance

Perfecting track maintenance

Dynamic stabilization has become indispensable to sustainable track maintenance. This is all the more important as traffic loads increase. Now, technological refinement brings further improvements for dynamic machines.

The ballast bed must be homogeneous and stable to fulfil its function: to distribute the dynamic forces produced by rail traffic into the formation, ensuring that the track geometry is maintained for as long as possible. The objective of dynamic track stabilization is to produce a homogenous ballast bed after the track has been maintained using a tamping machine.

More options through variable impact force

As a technological further development of our new stabilizing units, not only the vertical load and vibration frequency, but also the impact force can be adjusted. This is made possible by a hydraulically infinitely variable imbalance.

During dynamic stabilization, the impact force affects the track settlement the most. This is why the variable imbalance improves the controllability of track settling. This is particularly beneficial for our dynamic machines - tamping machines with integrated dynamic track stabilization. Compared to the conventional design, the imbalance can be switched off more quickly, allowing for a more homogeneous track geometry quality despite the frequent stop-and-go on the work site.

What is the benefit?

The variable impact force makes it possible to produce even smoother transitions. It allows producing exact ramps at the start and end of a work site or before and after fixed structures by increasing or reducing the impact force infinitely.

In addition, the impact force can be adjusted depending on the working speed. This is a decisive advantage in the maintenance of turnouts using universal tamping machines with integrated dynamic stabilization, for instance. Despite the machines’ irregular working speed, the ballast bed is settled in a constant manner and homogenised uniformly.

When working in densely populated areas, a reduction of the impact force lowers the propagation of the vibrations in the track area and minimises the effect on buildings and lineside residents.  

What is so cost-efficient about dynamic track stabilization?

Raising the sleepers during track tamping reduces the track grid’s lateral resistance in the ballast bed. The dynamic stabilizer anticipates traffic loads in a controlled way, exerting rather low stresses on the ballast bed. The controlled settlement increases the track’s resistance to lateral displacement considerably.

As a result, there is no need to impose speed restrictions after tamping. The homogenisation of the ballast bed secures the track firmly in position. It ensures that the track geometry is more durable. In addition, the action limit is reached much later and intervals between maintenance are extended. Maintenance costs are reduced.  

After tamping: The ballast underneath the sleepers has been compacted. The vertical load is not transmitted uniformly.

After stabilising: The vibration has re-arranged the ballast stones in a homogeneous structure. The vertical load is distributed optimally.

Dynamic track stabilization
Principle and effect

The variable imbalance (1) produces horizontal vibrations (2), the hydraulic cylinder (3) generates the vertical load (4).

Using an imbalance, the DGS stabilizing unit produces horizontal vibrations crosswise to the track axis. The dynamic track stabilizer travels in continuous action on the track while the stabilizing unit transmits controlled minor vibrations to the track grid via pressing rollers. At the right vibration frequency (32 to 35 Hz) the ballast stones begin to move and re-arrange in a denser and homogeneous structure. At the same time, the unit applies a vertical load to the track. It increases the consolidation effect and allows for modifying the longitudinal level of the track.

The main parameters are:

  • Vibration frequency
  • Impact force
  • Vertical load
  • Working speed

For more information see Publication “Track ballast in Austria” by Christoph Kuttelwascher and Michael Zuzic.