The contributions to the thematic focus "Tunnel Construction" in Volume 1 cover a wide range of topics, from technical procedures to digital technologies and sustainability aspects. In the area of construction methods, both conventional tunnel construction with low cover and machine-driven tunneling with its procedural techniques, planning fundamentals, and specific challenges are addressed. Following this, precast concrete segments, injections in tunnel construction, and the specifics of underground rail-bound connection points are discussed in three individual contributions.

Digitalization plays an increasingly important role in tunnel construction, as evidenced by contributions on BIM (Building Information Modeling)-based sustainability assessment, tunnel information modeling as a step towards the digital twin, general digitalization in planning, execution, and operation, as well as sensor technology and long-term monitoring. Finally, risk management in large tunnel construction projects is addressed, highlighting the complexity and challenges associated with such endeavors, including the necessity to identify, assess, and manage risks.

Volume 2 begins with a contribution on wind energy plants in reinforced concrete and prestressed concrete construction, followed by new or updated contributions that address the newly released series of standards DIN 1045 in 2023. The new DIN 1045-1000 establishes a concept of concrete construction quality classes (BBQ classes) for more complex planning and construction tasks in concrete construction, which is detailed and specified in the revised standards DIN 1045-1 (Planning, Design, Construction), DIN 1045-2 (Concrete), and DIN 1045-3 (Construction Execution).

Volume 2 concludes with the chapter "Standards and Regulations," including the new DAfStb guideline "Concrete Slabs and Roofs Made of Precast Hollow Slabs" from January.