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Measuring services in systematic maintenance SBB

Implementation and evaluation of field measurements, position correction of switches, remeasurements at control points

Vermessungsleistungen im systematischen Unterhalt


Schweizerische Bundesbahnen AG



Construction period:

2004 - now

Executing companies:

Sersa Maschineller Gleisbau AG

System Description

Switch pre-measurement (systematic maintenance and 3rd tamping process)

The AWG process (switch geometry recording) is designed for switch maintenance. Before tamping a switch, the current position of the switch and the switch connections is determined on the basis of the nominal position in the DfA (SBB´s infrastructure system database). The aim is to define an "optimal" position of the switch. The entire data flow from the field measurement to the tamping machine is digital. All clarifications and decisions are made before tamping, so that in the actual shift there is only tamping and no further pre-measurements are necessary. The sequence of the tamping work and the working direction can be flexibly adjusted.

The AWG process includes:

Field works (on the basis of excerpt DfA):

  • Recording (pre-measurement) of the switch to be processed
  • Recording of the adjacent switch(es)
  • Recording of the switch-feeder tracks
  • Determination of control points for remeasurement
  • Measuring instruments: Leica total station (TPS 1000/1100/1200) with the so-called free stationing TopoRail (or newer instruments with the same or better accuracy)


PC works (with Toporail software):

  • Evaluation of the field measurements
  • If possible: Establishing the nominal position of the switches
  • Mandatory: Adjustment to the neighbouring switch(es) not to be handled
  • Creation of an AWG protocol for the SBB site manager
  • Distribution of the AWG protocols approved by the SBB to Universal Tamping Machines


Works on switches with a switch tamping machine:

  • Feeding the AWG protocols into the PALAS system
  • Position correction with the switch tamping machine: Alignment and tamping of the switch. Absolute correction with reference to the AWG fixed points (with the PALAS measuring system).
  • Re-measurement at the control points (e.g. with the MEPHISTO track measuring device). In case of adjustments to the neighbouring switches there are inevitably deviations from the nominal geometry.
The NGV values (new track marks) are therefore not binding, but the control points in the AWG protocol. For this reason, the AWG protocol is unique and must be created anew for each switch maintenance.


Measuring was carried out during ongoing train operation.