Portsbridge Roundabout
| Portsbridge Roundabout | |||
| Location Map ( geo) | |||
 | |||
| The roundabout from the A3 to the south. | |||
| |||
| Location | |||
| Cosham | |||
| County | |||
| Hampshire | |||
| Highway Authority | |||
| National Highways | |||
| Roads Joined | |||
| A3, A27, A397 | |||
| Junctions related to the A397 | |||
Portsbridge Roundabout is part of Junction 12 of the M27, this junction also bridges the channel separating Portsea Island from the British Mainland. The motorway that flys over the junction is part of both the M27 and M275.
History
It became a junction in the late 1920s, when the A3049 Western Road was built. This meant traffic leaving the island over Ports Bridge was now given the choice of three roads: the old Portsmouth Road through Cosham, the new Northern Road, and the brand new Western Road.
In 1935, Western Road became a spur of the A27. Initially two forks, when the tramways were removed it became a long, thin roundabout entirely on the mainland, with direct access to Donaldson Road. The Ports Bridge Hotel stood nearby.
In 1959, with a plan for bypasses of Cosham, etc, forming part of the South Coast Trunk Road, had the A3 route flying over the junction, with the E-W route planning on grinding to a halt.
This changed with the M27 plans, which put the flyover E-W, rather than N-S. This was to be a roundabout interchange - as were both the trumpet junction with the M275 north and the directional-T with the M275 south. As such, provision for west-facing slip roads exist on the current roundabout.
The A27 opened first with space left for the road to continue. The Portsbridge Viaduct over the top was added later.
In 1993, a proposal to extend the M27 to the A3(M) would have made this the M27's junction 13.
Routes
| Route | To | Notes |
| (A3(M)), Portsmouth (E) | ||
| Hillsea, North End, Fratton, Copner, Portsmouth (W), Ferries | ||
| (M27, M275), Portsmouth (W), Paulsgrove, North Harbour, Fareham, Southampton | ||
| Waterlooville, Cosham, Highbury college, Southwick, London, Petersfield | A397 number does appear on signs | |
| London, Petersfield, Waterlooville, Southwick, Cosham | now A397 | |
| Donaldson Road | ||
| Fareham (A27) | now A27 | |
| The WEST, Southampton, Fareham, Portsmouth (W, C & Docks) (M275) | provision made for slip roads off roundabout, however junction changes to the main M275 junction meant that weaving would be too great. Sign destinations off gantry above roundabout | |
| London (A3(M)), Portsmouth (E), Havant, Brighton |
