Hergie® track Measurement system

pREcisiOn witH a systEM: HERGiE ®
Modern railway technology constantly faces new
challenges: trains are becoming more powerful, faster
and the intervals between them, ever shorter. The demands
on the infrastructure are rising in parallel.
The innovative Hergie ® track surveying system was
developed as part of the high-speed Cologne-Frankfurt
(Germany) rail project by Rhomberg Rail in cooperation
with the Bahnbau Wels subsidiary. Since then its high
quality has substantiated itself in a variety of other
projects.
This online measuring system for the adjustment and
documentation of track condition, compromises of
tachymeter-controlled track surveying trolley, which
optimally measures track position, cant, gauge and rail
inclination.
The measured data are compared “online” with the
pre-specified values for height, position and alignment.
Deviations to these values are shown in real-time on the
user’s monitor.
This means that they can be immediately and accurately
detected to be rectified on the spot.
HERGiE ® sOftwaRE
The “heart” of the Hergie ® track measurement system is
the software developed by RTE. It is available in
English and Spanish.
The system is based on a highly accurate, three-
dimensional single position.
At each measuring point, a total of five values are
measured: the coordinates in three dimensions, cant and
gauge.
All further required parameters can be derived from
these values. Moreover, it is also possible to monitor the
entire inner track geometry.
As the precision of the derived parameters depends
directly on the accuracy of the measured data, only the
best quality sensors are used.
The basic prerequirements in describing track geometry
using coordinates are:
• An accurate and stable reference-point network
• Accurate measurements of coordinates at
individual points
Longwave errors (wavelengths that are greater than the
distances between the positions of the instruments) are
directly proportional to quality of the reference-point
network.
In order to avoid the impact of longwaves, we
recommend that the reference-point network be
measured with a highly accurate, tachymeter-controlled
method. Mobile pillars containing a centring device is
recommended. They are also used to position the
tachymeter while the tracks are being aligned.
The reference-point network can also be used to verify
the track alignment.
Individual track alignment points are measured using a
precision tachymeter (direction angle ≥ 0.3 mgon). The
relative accuracy between two reference points at a distance
of approx. 60 m is subsequently below 0.5 mm.
Picture: The geometric height and direction relations are
shown at a single position of the track surveying trolley.
An inclination towards the centre of the track (longitudinal
inclination) is not taken into consideration. For a
standard track width (1.435 mm) the inclination in the
graphic is based on 1.500 mm (distance between the
two rail centres).
The displayed parameters are shown for each individual
position of the track surveying trolley.
The Hergie ® surveying system requires the following:
• a positioned and orientated total station in the
coordinate system of the reference-point network
• Geometry specified according to axis, gradients and
cant
In order to continuously provide the most accurate
results, all sensors, including the tachymeter have to be
regularly calibrated. The software is compatible and supports
regular calibration.