Safety is always the top priority in tunnel construction, and not only in Prague. That is why, before construction work began on Line D in the south of the city, the ground was examined particularly thoroughly. To ensure that imponderables in the subsoil do not become risks, around 60 HOCHTIEF experts carried out extensive geological investigations in 2020 on behalf of the Municipal Transport Authority. These were more comprehensive than ever, so that during construction "things would be brighter before the hoe," as the expert says.
The special thing about it is that the geological situation in Prague is extremely diverse. The alternation of layers of earth that are completely different from one another takes place even within a few meters. As one can imagine, this circumstance does not necessarily provide for more stability. In Prague, therefore, a particularly great deal of circumspection and experience was and is required. What came to light was correspondingly exciting. Geologist Radek Kozubik: "We found fossilized animals from the Ordovician period, i.e. an age of around 500 million years ago. Some of them now adorn the National Museum."