Since 2009 there have been 1647 procedures initiated in the Bundesrepublik for expropriation of landownership for road construction projects. As of August 2020, 448 of these procedures have been completed. Paragraph 19 of the Federal Funeral Street Act allows expropriations, "insofar as they are necessary for the execution of a determined or approved construction project" and are in accordance with Article 14 of the Basic Law for the benefit of the general public.
Of course, you can sue against that, and sometimes for decades (and thus prevent the project from getting ever finished, see the planned, and eventually forsaken A85 project that was meant to connect Stuttgart to Schwäbisch Hall roughly where today's B14 is [1]. They weren't able to seize two key farmer's fields and gave up - when the old farmer died in 2002, they build a nice bypass through there. Having lived in the area, a fast connection to the local capital would have made a lot of people's lives a lot better and saved millions of litres of fuel each year.
https://de.wikipedia.org/wiki/Enteignung#Wiedervereinigtes_D... (third paragraph):
Since 2009 there have been 1647 procedures initiated in the Bundesrepublik for expropriation of landownership for road construction projects. As of August 2020, 448 of these procedures have been completed. Paragraph 19 of the Federal Funeral Street Act allows expropriations, "insofar as they are necessary for the execution of a determined or approved construction project" and are in accordance with Article 14 of the Basic Law for the benefit of the general public.