Measuring services in systematic maintenance SBB

SBB measuring services in systematic maintenance

Implementation and evaluation of field measurements, switch position correction, 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)
Our AWG process (switch geometry recording) is designed for switch maintenance. Before tamping a switch, the current position of the switch and the switch connections are determined based on the nominal position in the DfA (SBB´s infrastructure system database). The aim is to define the switch’s "optimal" position. 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 easily adjusted.

Our AWG process includes:

Field works (on the basis of excerpt DfA):

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


PC works (with Toporail software):

  • Field measurement evaluation
  • If possible: Establishing the nominal position of the switches
  • Mandatory: Adjustment of 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: switch alignment and tamping. Absolute correction with reference to the AWG fixed points (with the PALAS measuring system).
  • Re-measurement at 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 are. For this reason, the AWG protocol is unique and must be uniquely created for each switch maintenance project.


Measuring was carried out during ongoing train operation.