|Principal stations (from north to south)|
The Caterham Line is a commuter service in south London and Surrey, connecting Caterham with London. Train services on the line are operated by Southern, and run to London Bridge, Charing Cross (off-peak) and London Victoria (peak). During peak hours trains divide at Purley, the other section being for the Tattenham Corner Line.
The Caterham branch was opened as the Caterham Railway on 5 August 1856, from a junction with the London, Brighton and South Coast Railway (LB&SCR), although the opening had been delayed because of a quarrel between the LB&SCR and the South Eastern Railway (SER), in whose territory the line was deemed to be. When the Caterham Railway went bankrupt in 1859, the SER took it over.
The line is double-track and electrified at 750 V DC using third rail. Immediately south of the junction station at Purley the Tattenham Corner Line leaves, and the railway follows the valley opposite Riddlesdown and the Oxted Line, which it parallels almost to Caterham. The branch has a line speed of 60mph.