Design of Zemplen 723

Long-span pedestrian bridges have become more and more popular around the world in the last decade. The municipality of Sátoraljaújhely in the North-Eastern region of Hungary wanted to join this international trend as they decided to build a bridge with a world record-breaking span as a new tourist attraction of Zemplen Adventure Park almost ten years ago. Their long-awaited dream became true in June 2024 when Zemplen 723 was opened to the public. The new pedestrian catenary bridge has 700.0m span, the longest of its kind in the world at the moment. The length of the superstructure is 700.5m, while the total length of the bridge (including the abutments with glass balconies) is 723.7m and it connects two hills of the Zemplen Mountains. Hence the name Zemplen 723. It is a catenary bridge, meaning that compared to classic suspension bridges it has no pylons and hangers so the elevation of the pedestrian deck follows the parabolic profile of the main steel cables, similarly to the ancient Inca rope bridges. The two-directional walkway is 1.2m wide and it is ~84m over the valley at midspan. The bridge is stiffened by a wind cable system and the overall static equilibrium is ensured by rock anchors. The article aims to present the challenging design tasks of Zemplen 723. The general arrangement and some structural details will be introduced together with the static and dynamic behavior of the bridge. Besides, it gives an overview of the extraordinary construction procedure of the superstructure, which required the installation of 149 tons (6490m) of steel cable.