The M25, the London Orbital Motorway, is the UK's busiest road, running almost in a loop around the Capital for 117 miles / 188km, although the Dartford Crossing over the River Thames is the non-motorway A282. It's frequently congested, despite being 4 lanes wide in most sections.
The M25's conception was in the Ringways plans in the post-war period - for a series of ring roads of increasing distance and standard. The M25, as now constructed, frequently runs close to the planned line of either ringway 3 or 4 for much of its length. The M25 number was chosen in the mid-1970s, although some sections were originally due to be numbered M16. The motorway was constructed between 1976 and 1986.
This video shows a clockwise journey along the M25 in Surrey, from Junction 10 for the A3 at Wisley Common near Cobham, to Junction 12 for the M3 Motorway at Chertsey. Part of this video is filmed in quite heavy traffic conditions.
