|Distance:||5.6 miles (9 km)|
|Route outline (key)|
The A3(M) is a motorway bypass for the A3 through Waterlooville. The idea was to create a continuous dual carriageway from Petersfield to Portsmouth. Most of this was done by upgrading the existing road, but around Horndean, Waterlooville and Cosham that wasn't going to be possible. As a result a whole new road was built around this section, and it was classed as the motorway A3(M).
Aside from the two terminal junctions, the road fails to meet any A-roads or motorways. It also falls short of the M27 by two miles - although original plans and indeed original signs had an extended M27 serve it.
Near its southern terminus the road crosses Portsdown Hill, a continuous ridge from Fareham to Havant. The road was due to cross it in a short 60-yard tunnel. This proposal was extended to 110 yards to get the full benefits, causing the plan to be scrapped and replaced by a cutting and a large bridge for the then-A333 (current B2177). This arch bridge was designed to make up for the damage caused with its distinctive design.