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.
The M25 or London Orbital Motorway is a major road encircling most of Greater London. The 117-mile motorway is one of the most important roads in the UK and one of the busiest. Margaret Thatcher opened the final section in 1986, making the M25 the longest ring road in Europe upon opening.
Junction 10 is the busiest section of the M25, with over 270,000 vehicles travelling through it every day. Due to the volume of traffic and the resulting queues, this area of their network has a very poor safety record and holds one of the highest collision rates across the National Highways network.
Magic Roundabout, SwindonThe Magic Roundabout is often listed as one of the most intimidating junctions in the UK. It's best shown in map form so you can see the complexity of its one-way systems feeding five roundabouts.