Railroad tunnel Praha-Beroun - as an example of underground structure in challenging karstic aresa

This paper discusses impressive project of the tunnel between Prague and Beroun. The length of the structure, spreading up to 25 km, leads to need of overcoming many risks, which may the tunnel encounter. The text is focused on specific issues typical for areas built by karstic rocks, which generally present one of the most dangerous environment for building architectural projects of any kind. It concentrates on description of Bohemian karst and karstic features, which are likely to appear in studied area. It strives for delimintion of risks and suggestion of proper investigtion and remedition methods, suituable for given project. A part of the paper is a brief introduction into main tunneling technology, applicable for tunneling construction and discussion of possibilities of particular tunneling method.