Moving further out of London, the character of each Ringway evolves. Ringway 3 was the only ring that was an entirely new route (or at least very nearly; it did make use of the pre-existing Dartford Tunnel). Unlike Ringway 1 and 2, which hijacked parts of existing road to make the circuit easier, this motorway route was intended to forge a new path through the suburbs. But while it was all to be built from scratch, it wasn't really a new plan at all.
Most of it would follow the line of Abercrombie's D-Ring, and in many planning documents, right through to the 1970s, this term is used interchangeably with Ringway 3. The difference was that now, instead of a surface-level dual carriageway, it was to be three or four lanes of motorway.
Its distance from the centre of London meant it would run mostly through the suburbs and around the fringe of the urban area, sometimes passing out into open country. It looks rather unlikely at first sight: a motorway planned to go through wealthy areas like Kingston-upon-Thames, Harrow and Sutton. Even so, more than half of it was built exactly to plan. The M25 around the north and east sides of Greater London is actually Ringway 3; planned and built as the M16 but absorbed into the post-Ringway M25 shortly before opening.
GLC and Ministry of Transport planning documents state quite clearly that Ringway 3 was designed to carry long-distance traffic that had no business in London. It existed as a bypass, handling traffic that was to pass around the urban area, leaving Ringway 2 free to distribute suburban traffic and Ringway 1 for those heading into the central area. Fair enough. But if this is the case, then what was the point of Ringway 4? The north, west and south sides of Ringway 3 certainly look for all the world like another suburban distributor, much like Ringway 2.
The answer to these things can usually be put down to the GLC and the Ministry not quite seeing eye to eye. Quite often it's a wonder that they ever accomplished anything given the level of mutual disagreement that seems to have existed. GLC documents, up to the early 1970s, usually talk about three ring roads around London, of which the third was the responsibility of the Ministry of Transport. This would make Ringway 3 the outermost and would explain why it was expected to act as the bypass for long-distance traffic.
The Ministry themselves had other ideas, and were still working on age-old Trunk Road plans for the North Orbital Road and South Orbital Road, which had been rumbling on since the creation of Trunk Roads in 1936. Of these plans, the A412, A405 and A414 made up the North Orbital in the Watford area, but little else had been done.
By the 1950s it was assumed that the Ministry would provide a motorway to do the same job - M45 was suggested as a number, it being a contraction of the number 405 - and it seems that, despite the Ringway proposals, the Ministry of Transport was still building another ring road even further out. Eventually this became known as Ringway 4, but the above explains why it sometimes doesn't seem to fit in with the rest of the jigsaw quite as seamlessly as it should.
The following pages describe the route running clockwise from the M1.