B172n Pirna bypass targets full opening in October 2026

The B 172n is the roughly 3.8 km southern bypass of Pirna, whose main structures are the Kohlberg tunnel (315 m) and the Gottleuba valley bridge (916 m long, up to 70 m high). The western section has been operating since December 2022, and costs have risen per DEGES/Wikipedia from about €97 million (construction start 2016) to roughly €280 million (as of November 2025). Full traffic release is currently planned for October 2026 (originally targeted for 2023); the DEGES project page also notes that potential concrete-quality defects on the Gottleuba valley bridge are being reviewed, which could affect the schedule. Update (29 October 2026): because of voids in four of the five haunches of the Gottleubatal bridge, caused by formwork remains in the concrete, DEGES now expects the bypass to open fully only in 2027. The date is a placeholder: only the year 2027 is given (Verkehrsrundschau citing dpa, 29 October 2026).