running approximately parallel both to the coast of the solent and to the a27, the m27 starts as an eastwards continuation of the a31 from bournemouth and poole, meets the a36 from salisbury, crosses the wessex main line railway, and then meets the m271 to central southampton. after the m271, the road becomes a dual four lane motorway and passes rownhams services, it then meets the m3, (two lanes going off, two lanes continuing to the other side of the junction) reverting to a dual three lane motorway as it passes to the north of southampton, passes southampton airport, meeting junction 7 and becoming dual four lanes again, then becoming dual three lanes after junction 8, it then runs alongside the west coastway line as it heads south-east towards fareham. it then runs alongside the northern outskirts of fareham, briefly with a fourth climbing lane in either direction, before its junction with the m275 to portsmouth. very shortly after this point the motorway ends, becoming the a27, a four lane dual carriageway almost to motorway standards until the junction with the a3 (m) motorway. the official reason for this section of road not being a continuation of the motorway is the hard shoulders being too narrow. although the m275 which the m27 junctions with, has no official hard shoulders throughout its entire length.