Flowin' Footbridge – Parametric low-carbon concrete pedestrian bridge in Moganshan, China

Moganshan, nestled in the hills of Zhejiang province just a few hours from Hangzhou, is one of the best-known mountain tourist areas in eastern China: bamboo forests, historic colonial residences, a sense of place built on tranquillity and the landscape. The Deqing County Cultural Tourism Development Group commissioned a new pedestrian bridge to integrate an experiential route into the fabric of the tourist district. The challenge was not only technical (supporting pedestrian traffic over a short span) but also one of identity: to design a contemporary structure that would engage with the landscape’s sensibility without reducing itself to a mere vernacular reference or an out-of-scale authorial gesture.

Barberio Colella Architetti, with Angelo Figliola and collaborator Zhenghui Chen, developed the project entirely using a parametric workflow, Rhinoceros and Grasshopper for modelling, Karamba for integrated structural analysis. The bridge’s form is not drawn out in plan and then verified: it emerges from the simulation of loads and constraints, so that every curve and every section is the direct result of structural behaviour. The result is a fluid, ‘flowing’ line (hence the name Flowin’ Footbridge) which crosses the site without imposing rigid directions on the surrounding landscape.

The construction system combines two materials with distinct roles. The deck and parapets are composed of modular blocks of eco-concrete: a low-carbon concrete that reduces CO₂ emissions compared to standard concrete thanks to the partial replacement of Portland cement with less energy-intensive binders and the use of recycled aggregates. The blocks are prefabricated with variable geometries (the sequence can be seen in the project’s Sections Progression) and are assembled in succession using post-tensioned steel tie rods that ensure the structural cohesion of the whole. The parapets, also made of steel, complete the formal composition and serve as a guardrail. The layering of discrete stone blocks and continuous steel tie rods is the principle on which BCA also worked in Hypar Gate (Troyes, 2016) and Additive Stereotomy: a contemporary stereotomic language, where the geometry is generated by an algorithm and translated into manufacturable modular components.

The project is currently unbuilt: presented as a poster at the joint ACADIA/CAADRIA 2023 conference, Flowin’ Footbridge documents the state of the art of BCA’s research into the integration of parametric design, computational structural analysis and low-impact materials applied to small-scale public infrastructure. For the Chinese tourism and cultural client, the bridge is an identity asset; for research, it is a publishable case study on the reduction of the carbon footprint of pedestrian infrastructure when the geometry itself becomes a tool for structural optimisation.