On 22 April 2006, the parts of the tunneling machine "Tosca", which will drill
the eastern tube of the new underground line, were lifted into the starting pit
at the station Bonner Wall. This is the center shield (Mittelschuß), the
heaviest part with a weight of 176 t. The view onto the rear end shows the 14
pairs of thrust cylinders placed at the outline, and some smaller cylinders
between them which will obviously actuate the tailskin (Schildschwanz). The
latter will surround the area behind the center shield, where the segment lining
will be installed. The four large mounts at the frame inside the center shield
seem to be intended for the erector, which lifts the segments into their
position.
<p>
Digital photo by
<a href="http://www-users.rwth-aachen.de/christoph.schmitz2/index.html">Christoph
Schmitz</a>
(<a href="mailto:christoph.schmitz2@post.rwth-aachen.de">christoph.schmitz2@post.rwth-aachen.de</a>)