M27 Southampton Junctions

Scheme outline

Improvements to M27 junction 8, the nearby Windhover Roundabout and 31 junctions on the A3024 between that point and the Six Dials junction in central Southampton, in addition to widening of the A3024 across two railway bridges. The scheme is highly unusual as it is being carried out by Highways England, who operate trunk roads, and at their expense, but the work will almost all take place on non-trunk local authority roads operated by Southampton City Council. The name of the scheme, which refers to the M27, presumably derives from the fact that the M27 is the only Highways England road involved.

The scheme is made up of several distinct parts:

  • Upgrade work to M27 junction 8, including wider sliproads, full signalisation of the roundabout and improved facilities for non-motorised users
  • Upgrade work to the A27/A3024/A3025 Windhover Roundabout, including wider approaches to the junction and installation of traffic signals
  • Construction of a new pedestrian and cycle bridge on the north side of the A3024 Bitterne Rail Bridge, which will allow more space for motorised traffic on the existing bridge 
  • Replacement of the Northam Road Rail Bridge with a new dual carriageway bridge
  • Changes and upgrade work to 31 signalised junctions on the A3024, including road widening at 22 locations, and all including improved facilities for pedestrians and cyclists

The overall effect of the works will be to provide smoother, faster journeys in and out of Southampton on the A3024, removing constraints that narrow the road in several locations. It will also remove the "Bitterne Gating System", a system where traffic lights on the A3024 are linked in order to hold back traffic on the edge of the urban area and restrict access to the main road in an attempt to manage traffic entering Southampton in the morning peak. The system was implemented in the 1970s and is now considered to be causing more problems than it solves.

The rationale for this scheme - and the fact it is being paid for and carried out by Highways England under the direction of the Department for Transport - appears to be that the M27 north and east of Southampton has suffered extraordinary growth in traffic levels in the last 15 years, with traffic counts up nearly a quarter. Anticipated growth at Southampton Docks and new housing east of the city are expected to add to the pressure on the motorway in coming years. Much of the existing congestion in peak hours is thought to derive from the traffic signals and bottlenecks on the A3024, and traffic approaching from the east attempting to bypass the route by continuing on the M27 and using other approaches to the city.

By making the A3024 run more smoothly and increasing its capacity, it appears that Highways England are hoping to reduce pressure on the M27 and its junctions. The cost of the necessary works - upwards of £130m - are far beyond anything a local authority could contemplate, so uniquely central Government have directed Highways England to intervene on behalf of Southampton City Council in order to resolve a problem on local roads that is affecting the trunk network.

Under construction
Other upgrade
for use by all traffic
Highway authority


11 February 2020

The scheme has been broken into several projects:
Highways England are responsible for M27 J8 and the nearby Windhover Roundabout, and are expected to start work later this year.
Their project will complement a separate project from Hampshire County Council to upgrade the A3025 around the Windhover Roundabout, which is expected to start work next year.
Southampton City Council are responsible for the A3024. Throughout 2019, they completed the work on the junctions between Bitterne and Bursledon. The section between the City Centre and Bitterne was perceived to be too troublesome, especially as it involved working with the railway and could easily delay the whole scheme. As a result, that section will now be delivered by the city council at a later date.

More information