£4bn underground line mooted to connect Southampton and Portsmouth

Southampton could see a brand new underground rail line as part of £45bn of transport improvements across the South East put forward by the region’s transport body.A new rail link which would connect Southampton Central with Netley, linking up Portsmouth Harbour and improving capacity on the Botley Line has been outlined by Transport for the South East (TfSE).The package of intervention outlined in the Strategic Investment Plan for the South East includes a core package of measures and an enhanced rail package for Southampton and Portsmouth which together total £4.6bn in capital construction costs.The core package includes upgrading the Botley line to twin tracks, adding platforms at Portsmouth Harbour station, improving signalling on the Netley line and Sidings at Totton.The TfSE plans for an enhanced package, drawn up by Solent Transport, local authorities and Network Rail, identified the tunnel between Southampton Central and St Denys as a key bottle neck in the current rail network. New stations would also be built at Southampton Central and in the city centre.The consultation paper said: “A longer-term package of interventions is needed to unlock significant capacity and, potentially, shorter journey times between Southampton and Portsmouth City Centres. This could include developing an entirely new rail link (most likely underground) between Southampton Central and the Netley Line”.The current time to travel from Southampton to Portsmouth averages around 40 minutes. The upgrades can shave up to a quarter of the time off the journeys and allow for services every 15 minutes, a similar frequency to TfL’s London Overground services.The enhanced package would also include new freight paths to ease congestion on commuter lines. A rail freight hub has been mooted at both Havant and Fratton as well as upgrades to Southampton’s port rail freight facilities.Last month, TfSE outlined how a £3.2bn extension of Crossrail into Kent could be funded. The long-mooted extension would see Crossrail continue east to Ebbsfleet and on to Gravesend. A public consultation on the TfSE proposals, which would be built over a 27-year period.