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
London Outer Orbital Path London Outer Orbital Path The London Outer Orbital Path — more usually the "London LOOP" — is a 150-mile (242 km) signed walk along public footpaths, and through parks, woods and fields around the edge of Outer London, England, described as "the M25 for walkers". The walk begins at Erith on the south bank of the River Thames and passes clockwise through Crayford, Petts Wood, Coulsdon, Banstead, Ewell, Kingston upon Thames, Uxbridge, Elstree, Cockfosters, Chingford, Chigwell, Grange Hill and Upminster Bridge before ending at Purfleet, almost directly across the Thames from its starting point. Between these settlements the route passes