When Swiss engineer Robert Maillart set out to bridge the terrifyingly steep Salgina Ravine near Schiers in 1929, he faced a structural nightmare: extreme terrain, harsh weather, and severe budget limits. Traditional bridge builders of the era favored massive solid stone arches or heavy steel trusses. Maillart, however, proposed a radically minimalistic concept: a three-hinged arch using a hollow reinforced concrete box girder.
\n\nMaillart realized that the interior core of a massive, solid concrete arch does surprisingly little structural work while adding tremendous dead weight. By removing the useless core and forming the cross-section into a thin-walled, hollow box, he drastically reduced the mass of the bridge without sacrificing stiffness. The hollow shape provided incredible resistance against bending and twisting forces caused by alpine winds, while allowing the arch and deck to work together as a unified structural shell.
\n\nThis reduction in weight was critical for construction logistics. Building over a 90-meter-deep ravine meant that timber scaffolding—known as centring—had to be erected from the gorge floor. A heavy, solid concrete bridge would have crushed the temporary wooden falsework designed by master carpenter Richard Coray.
Maillart's hollow design was light enough to be poured safely in sections on a relatively delicate wooden scaffold. \n\nFurthermore, using less concrete and steel meant lower material costs, allowing Maillart to submit the lowest bid among 19 competing designs. When completed in 1930, the Salginatobel Bridge spanned 90 meters with unprecedented elegance, proving that structural efficiency and high art could be one and the same.