M25 motorway and Thurrock off junction 31 (to the east of London). Cobham services opened on 13 September 2012. Originally, the M25 was unlit except for sections around Heathrow, major interchanges and Junctions 23–30. Originally, low pressure sodium (SOX) lighting was the most prominent technology used, but widening projects from the 1990s onwards have all used high-pressure sodium (SON) lighting and this has diminished the original installations. By 2014 only one significant stretch was still SOX-lit (Junction 25–26) and the units were removed the same year. The motorway passes through five counties. Junctions 1A–5 are in Kent, 6–14 are in Surrey, 15–16
Safety on the London Underground train. Several stations on the Jubilee line extension are fitted with platform edge doors, which prevent people from falling or jumping onto the tracks. Terrorism in the London Underground has been a major concern because the Underground's importance makes it a prime target for attacks. Many warnings and several attacks, some successful, have been made on the Underground, the most recent on 21 July 2005, although in that case only the detonators exploded. The most recent attack causing damage was on 15 September 2017, when a man detonated a homemade bomb on a District line train at Parsons Green station.