THE ENGINEERING
How the Bernina Line Climbs the Alps
The adhesion railway, the Brusio spiral, the 7% gradients and the UNESCO listing — the engineering behind the ride.
See Bernina Express day trips on GetYourGuide ↗Climbing on grip alone
The Bernina line's quiet audacity is that it climbs the Alps without a rack. Most high mountain railways use a toothed rail and a cogwheel to haul themselves up steep grades; the Bernina holds gradients up to seven percent on plain wheel-to-rail adhesion, making it the highest transalpine crossing and one of the steepest adhesion railways anywhere. When you feel the train grinding upward toward the pass, that's friction and nerve doing the work, not a hidden cog.
The Brusio spiral
The line's most elegant solution to the gradient sits just above Tirano: the Brusio circular viaduct, a nine-arch stone bridge on which the train loops a full 360 degrees over its own tracks, opened in 1908. Where the valley fell away too steeply for a straight climb, the engineers chose an open-air spiral rather than a tunnel or a rack — buying height in a graceful curve. It's now one of the most photographed structures on the whole railway.
Bridges, tunnels and a watershed
By the railway's own count the Bernina Express journey crosses 196 bridges and passes through 55 tunnels, climbing past the Morteratsch and Palü glaciers to Lago Bianco at the pass — a lake on the continental divide, where water parts to flow toward the Adriatic on one side and the Black Sea on the other. The line was built to sit within its landscape rather than blast through it, which is exactly what UNESCO would later honour.
Why UNESCO listed it
In 2008 UNESCO inscribed the Rhaetian Railway's Albula and Bernina lines as a World Heritage Site — recognition of a railway as a cultural achievement, for how boldly and harmoniously it was engineered into a difficult mountain landscape a century ago. Riding it, that's the thing to feel alongside the scenery: not just where you are, but what it took to lay a railway here at all, and to keep it running over the roof of the Alps.