Tunnels for research © HOCHTIEF

A class of its own

An X-ray laser that promises revolutionary findings to scientists. A project that is second to none worldwide. For this laser, HOCHTIEF has constructed a tunnel system down to 36 meters below Hamburg. Total length: 3.4 kilometers. And yet millimeter precision. Because the high-tech equipment does not like deviations. Nor does Gunnar Reimann.

HOCHTIEF engineer Gunnar Reimann enjoys doing pioneering work. It's something he is familiar with from the Gotthard Tunnel, from a Bosporus undercrossing, and from many other large construction sites. Then suddenly this project somewhere between Hamburg and the federal state of Schleswig-Holstein comes along. Uncharted territory again. What Reimann has to build is not just one tunnel. Not two, three or four either. It's eleven tunnels all at once. "Like an arm extending into the hand and fingers" is how Reimann describes the cave-like branching work of art.

Packed with potential
XFEL—four letters that stand for progress. In May, the biggest and most powerful X-ray laser in the world started operations in Reimann's world of caves. It produces ultra-short light flashes—27,000 per second. The goal is to provide scientists with new research possibilities and insights into processes nobody has ever seen before. Atomic details of viruses and cells that promise tremendous innovations for cancer research, astronomy and even industry shall be made visible. In September, some 350 scientists will move into the research center in Hamburg. It remains to be seen then if Germany's most expensive experiment with its investment volume of 1.2 million euros will keep what it promises.

Engineer Reimann, in any case, has kept his word. To build a perfectly fitting system of tunnel tubes—that was the assignment which began as long ago as in 2009. With many questions to be answered, too. What does the driving machine have to be like? How do we stay within budget?

11 at one go
Reimann invests an entire year into the planning and broods over the technical work sequences. How do the individual gear wheels interlink? He designs a steel girder system on which the more than 100-meter-long and over 400-tons-heavy tunnel boring machines can be moved forward step by step. The result: The HOCHTIEF team concluded its work in 2011 after only one third of the originally planned time and for many million euros less.

Only one promise: the solution!
"A successful tunnel project needs good planning, good people and good luck. The better the planning, the less importance good luck has", says Reimann who leads the Machine Engineering team within HOCHTIEF's Tunneling unit today. The challenge: The laser light has to hit the end point exactly. "That's why we had to drive the tubes with absolute accuracy."

And it worked: "'The tunnels are a precision landing, really good," Reimann recalls. Just how meticulously and precisely he and the other HOCHTIEF team members worked became evident at the time of breakthrough. The deviation was only a few millimeters. Measured with lasers, of course.

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