The new bridge “Lahnsteg Nauheim”, Wetzlar: slender, elegant, parametrically designed

This paper outlines the planning of a bridge in central Germany. Scheduled for construction in mid-2024, this new bridge is a replacement for a century-old pedestrian bridge crossing the Lahn river.

The proposed bridge will be an airtight-welded arch bridge, employing steel cross-sections in both the arch and tension member. Designed as a single-span, the arches extend 48.0m over the Lahn. The two arches have a flat rise of 4.65m, supporting the roadway through 9 inclined flat steel hangers.

This paper delves into the structural engineering aspects, exploring challenges inherent in the design process. An examination of the parametric design process, facilitated through 3-D modeling in Rhino® and Grasshopper®, will be presented, along with insights into their interface with the finite element modeling software, RFEM®. This process enables an engineering approach to form-finding and structure optimisation through iterative design checks for various elements and stages of the structural analysis.