Ligne de Sceaux
"La Ligne de Sceaux" (The Sceaux Line) was a railway line in France running from Paris to some of its southern suburbs, including Sceaux from which it takes its name. It is now part of the RATP's RER line B, though the name is still used informally.
The line originally opened in 1846, built under the supervision of chief engineer Jean-Claude-Républicain Arnoux. It ran from a Paris terminal near the present-day metro station of Denfert Rochereau through Bourg-la-Reine - where a branch to Robinson via Sceaux (actually the original main line of 1846) originates - Massy Palaiseau (present-day TGV connection), and Saint-Rémy-lès-Chevreuse to Limours. Plans to extend it to Chartres never bore fruit, as competing lines made the project superfluous.
It was originally built with a track gauge of 1,750 mm (5 ft 8 7⁄8 in) and very tight bends in the area around Sceaux: Arnoux had devised a new articulation system that allowed train wheels to turn, the système ferroviaire dit Arnoux ("Arnoux system"), and the line was to test his prototypes. Shortly after opening, the bogie was invented in the United States, rendering Arnoux's system pointlessly complicated. The section of track from Bourg-La-Reine to Sceaux was rebuilt to the current terminus of Robinson.
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