Cal Stadium Renovation - Trimble

Pre-Surveying
Helps Keep
Railroads on
Track
The need for speed and ride comfort for both passenger
and freight operations puts high demands on the
fundamental elements of railway infrastructure—the
roadbed and tracks. Roadbed and track quality must be
established during initial construction and maintained over
time. This involves proper ballast laying and grading, sleepers
(ties) positioning, and, especially, ballast tamping and
compressing for exact rail positioning. Since much of the
work—whether new construction or routine maintenance—
depends upon accurately establishing or verifying the track
position, high-accuracy survey technology is critical.
Track Renewal in Central Germany
All photos by Bernd Schumacher
In 2011, Germany’s primary railway service provider Deutsche Bahn AG awarded a contract to Spitzke SE, one of Germany’s
biggest rail infrastructure companies, for a track-renewal project in the state of Hessen. The project required
replacing the existing sleepers and rails along roughly 8 km (5 mi) of the route between the towns of Sontra and Cornberg.
Part of a main north/south line, the route is used primarily by freight trains as well as regional and night passenger trains.
As a first step, a track-renewal train replaced the old
sleepers and rails with new ones. Next, the approximately
placed track was precisely aligned, both horizontally and
vertically. For this, Spitzke SE used a Stopfexpress 09-3X
tamping machine from Plasser & Theurer. These huge,
rail-bound machines raise the track by the required
amount, compress the ballast beneath every sleeper
using hydraulic tamping picks, and perform the lateral
alignment during the same run. The amount of horizontal
or vertical correction required depends on the track
deviation from its specified position after track-laying or
ballast maintenance work has been done. This deviation
is determined by a process called pre-surveying.
“Before starting any tamping run, the pre-surveying process
precisely captures the current track position in order
to determine the deviation and to obtain the right lifting
and displacement values for the track,” explains Spitzke
SE Surveying Engineer (Dipl. Ing. (FH)) Falko Soffner, in
charge of pre-surveying tasks for the Sontra/Cornberg
track renewal project.
Technology&more; 2012-1
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To perform pre-surveying work, Spitzke SE uses the
Trimble GEDO® CE Trolley System. This track measurement
system consists of two lightweight trolleys, each of
which can be easily moved along the rails by the surveyor
or assistant. One trolley is equipped with a Trimble S-series
Total Station, while the second carries a fixed prism.
The trolleys also have sensors to measure the distance
between the rails, the cant (superelevation) and other values.
All the data is transferred wirelessly to a Trimble TSC2
or TSC3 Controller, which calculates the track deviation
from the specified position. The trolley system, combined
with Trimble GEDO Vorsys, Trimble GEDO Office and
Trimble GEDO Tamp software, provides railway-level accuracy
with operational speed and flexibility.
Measurements are made using control points typically
installed in each catenary support. The total station accurately
measures the distance and the height difference
to the control point and sends the data to the TSC2 (or
TSC3) controller. The measurement is repeated at the
next catenary support. The prism trolley is then moved