The SDV LSW system combines different methods which have separately
proven themselves over the past years: the laser beam for the
determination of the TBM position and the electronic hose water
level for the determination of the absolute altitude.
The use of the comparatively simple, reliable and furthermore
cost-effective laser-target-systems allow straight drives up to 400m,
provided that a high-quality laser is used. The precision of those systems is,
however, restricted by the phenomenon of refraction, a mostly vertically
affecting deflection of the laser beam by horizontally lain layers of
air in the pipeline.
In extreme cases, this refraction, frequently occurring at the first
metres of altitude levelling, leads to large deviations. The SDV LSW
system developed by CENTERLINE GmbH faces this problem.
The electronic hose water level which continuously calculates and displays
the altitude of the TBM plus the information received from the active
target unit allows the precise navigation of the TBM in both directions,
horizontal and vertical.
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