Metropolitan line the top green light over a yellow light, and clear two green lights. The Metropolitan line's suburban rail character opposed to other London Underground lines is also shown by the long distances between stops. Eight of the top 10 furthest apart stations on the Underground are on the Metropolitan line. The section between Chalfont & Latimer and Chesham is the longest at , whilst the Finchley Road to Wembley Park section is the second longest, and Rickmansworth to Chorleywood the fourth longest overall. The Metropolitan line is the only London Underground line to operate an express service. Designed for commuters
Attacks on the London Underground On 9 December, a van bomb partially detonated at the car park of Woodside Park station. No-one was injured but it caused evacuations and disruptions. A device exploded at an underground passageway at South Kensington station on 3 February 1993. On 20 December, a device exploded in a litter bin in Northfields station. On 21 December, coded bomb warnings from the IRA resulted in a paralysed London Underground system, as tens of thousands were evacuated from 100 tube stations during the morning rush hour. In 2005 two groups of Islamist extremists attacked a number of underground lines and bus routes