Immediately after Chedde, the line goes into steep slopes, which quickly reach the record value of 90 mm/m (9 %). Indeed, it needs to climb up a gorge in a tough environnement. The road faces the same conditions, and in the 1970s an elevated expressway was built above the Chedde chemical plant: the Égratz viaduct. The railway climbs under the viaduct on some distance, up to Égratz tunnel that crosses a rocky spur. The railway then continues its 90 mm/m ascent.