| + names abbreviated whenever possible° heavy rail# not managed by IP (and/or its predecessors)† closed (completely)‡ planned
 | †† reopened†‡ reopening planned‡† cancelled project‡‡ planned using former project↑  replaced using former trackbed
 | ² 7 ft 1⁄4 in (2,140 mm) Brunel gauge ᴮ 1,668 mm (5 ft 5+21⁄32 in) Iberian gauge ⁱ 1,435 mm (4 ft 8+1⁄2 in) Standard gauge ¹ 1,000 mm (3 ft 3+3⁄8 in) Metre gauge 
 | ³ 3 ft (914 mm) 3-foot gauge ⁹ 900 mm (2 ft 11+7⁄16 in) 900 mm gauge ⁶ 600 mm (1 ft 11+5⁄8 in) 2-foot/600 mm gauge ⁴⁺ Larmanjat monorail 
 
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