How the M25 got its name. The same principle explains the M25, which at its oldest point (the section crossing Surrey) follows the path of the older A25. These roads are all in the South East, which forms Zone 2 of the country's motorway system. This explains why they all contain 2 somewhere in their name.
Junction 23 on the M25 in Hertfordshire is the single biggest gyratory on the whole of the National Highways network. At about 1.2km in circumference, the junction sees some of the highest traffic flows on the M25.
Firstly, I had to plan the route. All I knew was that it would make sense to start and finish at the Dartford Crossing, although at the time I didn't realise that pedestrians couldn't walk across the bridge. The M25 motorway circles London but because it is a motorway, you can't actually walk on the M25 itself.
Thus, any rightward motion in a circular fashion is known as clockwise, often denoted as CW. But you may be wondering which way is counterclockwise? Subsequently, the circular motion towards the left is counterclockwise or anticlockwise, often denoted as CCW and ACW, respectively.
One would run outside north London, to be called the M16, and one around south London, the original M25. Plans developed into a single ring motorway, now just called the M25, and work began in 1975.