Template talk:Chatham Main Line

Sydenham (Hill)/Penge Tunnel
List of tunnels in the United Kingdom gives a value of 2,141 yards; while London, Chatham and Dover Railway: Tunnels says 2,200 yards. What is the correct length? Useddenim (talk) 22:37, 23 January 2013 (UTC)
 * According to
 * it's 1 mile 381 yards = 2141 yd. -- Red rose64 (talk) 23:03, 23 January 2013 (UTC)
 * I have a theory for the origin of the 2200 yd figure. If that figure is taken from a source which rounds tunnel lengths to the nearest quarter mile, 1 mile 381 yards rounds to $1 1/4$ miles (because 381 yards is closer to 440 than to 0) - and $1 1/4$ miles is exactly 2200 yards. -- Red rose64 (talk) 09:48, 24 January 2013 (UTC)
 * I have a theory for the origin of the 2200 yd figure. If that figure is taken from a source which rounds tunnel lengths to the nearest quarter mile, 1 mile 381 yards rounds to ⇭⇭⇭ miles (because 381 yards is closer to 440 than to 0) - and ⇭⇭⇭ miles is exactly 2200 yards. -- Red rose64 (talk) 09:48, 24 January 2013 (UTC)