Webnet micro: Transparent protection over Zurich's tracks

Initial situation and concept:

The Negrellisteg leads across the wide track field near the main station in Zurich. Here, the pedestrian bridge creates an elegant connection between two city districts that were previously separated by the track field. On one side, the generously modernized Kreis 4 is growing, and on the opposite side, the industrial and residential district Kreis 5 is pulsating.

The architecture of the bridge opens up a unique perspective of the urban area on both sides of the bridge when crossing the densely trafficked track field. To enable this view, the project planners chose transparent elements for the bridge structure above the walkway. This leaves the field of vision for pedestrians largely unobstructed despite the protective parapet.

In order to consistently unfold this transparent aesthetic, Jakob Rope Systems was allowed to integrate the Webnet micro stainless steel mesh system for the bridge construction project. The planners on this bridge construction project were: Conzett Bronzini Partner (Chur) as lead civil engineers, Diggelmann + Partner (Bern) as civil engineers for structural design and 10:8 Architekten (Zürich). The construction at the Negrellisteg was carried out by the Ticino-based steel construction company Officine Ghidoni SA as general contractor. In October 2021, the completed Negrellisteg received the Swiss Prix Acier 2021 award for its elegant and functional steel structure.

Design and implementation:

The parapets on the deck of the bridge are equipped with a dense stainless steel mesh. Above the parapets, the installation of an overthrow protection was required, which continues the transparent design in a meaningful way. An ideal application for Webnet micro.

The flexible and transparent net system was flexibly adapted by Jakob Rope Systems in a wide range of rope diameters and mesh sizes as required. Webnet micro with a mesh size of 35 millimeters was chosen as overthrow protection on the Negrellisteg. On both sides of the bridge, 14 net panels each made of Webnet micro were installed. With a net height of 1.40 meters, they extend the parapet below to a total height of 2.20 meters – without restricting the pedestrians' field of vision too much. The net panels are tensioned by individual centerboard supports, between which horizontal and vertical edge ropes (Ø 8 mm, stainless steel, 6 × 7+ WC) are installed.

Details and geometry:

• 2 × 14 Webnet micro panels (each between 8.50 m and 10 m long, 1.40 m high)
• Total length: 2 × about 132 m