Although the majority of journeys involving central London are made by public transport, car travel is common in the suburbs. The inner ring road (around the city centre), the North and South Circular roads (in the suburbs), and the outer orbital motorway (the M25, outside the built-up area) encircle the city and are intersected by a number of busy radial routes—but very few motorways penetrate into inner London. A plan for a comprehensive network of motorways throughout the city (the Ringways Plan) was prepared in the 1960s but was mostly cancelled in the early 1970s. The M25 is the longest ring-road motorway in the world at 121.5 mi (195.5 km) long. The A1 and M1 connect London to Leeds, and Newcastle and Edinburgh.