The A3 is the historic route south-west from London to Portsmouth, connecting the capital with the home of the navy. Upgrades have been happening to it since the early part of the 20th Century, but since the 1960s, it has been turned into a near-motorway (in fact, at one time there were plans afoot to renumber M3 as M30 to free up that number for a fully upgraded A3).
However, appearances are deceptive - the Esher Bypass, which is a full motorway formation, is the exception and much of the route has occasional right-turns. Until 2011, of course, Hindhead formed the most notorious bottleneck - the one place the road returned to a single-carriageway, snaking through a village, protected National Trust woodland and a set of traffic lights. After five years of work, a tunnel under the Site of Special Scientific Interest closed the gap that had prevented this route from reaching its full potential for so long.
The short blue line at the Portsmouth end of the A3 is an entirely isolated motorway, rather like the M2. This one just bypasses a nasty bit of the A3 through Waterlooville and Horndean, though it does it in considerable style in comparison to the rest of the route, which is almost motorway standard but certainly not a motorway.
The M27 stops just four miles short of reaching the A3(M), throughout which it is four lanes wide, grade separated and has very nearly full width hard shoulders. Despite some pieces of road (like the A57(M) or Chiswick flyover section of M4) being a long way below this standard, the fact that its hard shoulders are a few inches too narrow is apparently the official reason for its reluctance to turn blue.
The A3(M)'s number gives you a headache if you think about it too long. It implies that this is a section of the A3 with motorway restrictions. However, running parallel through Waterlooville is the A3. So that means... two A3's? Erm...
You're not looking at the whole A3 and A3(M)
This page is about the parts of the A3 and A3(M) that are designated a motorway or that have motorway characteristics. Other sections of this road will not be featured here and will not count towards the length of the road as shown below.