This 25-mile section will obviously require redoubling, with the constraining single-line sections (totalling 12½ miles) imposed in 1990 abolished.
The route is well-engineered and perfectly capable of higher line speeds than currently exist (70mph). Footbridges will have to be replaced where they were removed when platforms were put out of use and those platforms at stations used intensively by commuters will require lengthening to 12-cars.
Electrification of the whole route between Hurst Green and Brighton will be necessary and with overhead (OLE) AC rather than third rail DC. This is in line with current Network Rail studies considering conversion of the Sanderstead-East Grinstead route to OLE and associated new electrification of the Uckfield line.
BML2 into Tunbridge Wells
With the Uckfield line transformed into BML2, it will be necessary and desirable to reopen the former main line into Tunbridge Wells (West). Both double track spurs from the Uckfield line at Birchden and Ashurst Junctions will be reopened to enable trains to operate to/from Tunbridge Wells to Brighton via Eridge and to/from London via Oxted.
This obviously includes OLE electrification commensurate with BML2, eventually linking into the future OLE converted Tonbridge Main Line.
Tunbridge Wells (West) would be reopened with three 12-car platforms. The development could be undertaken in association with the supermarket retailer where far more economic use could be made of the land currently used as an open air car park.
East of Tunbridge Wells (West) the single-line Grove tunnel would be rebuilt for double track and the Grove spur accordingly relaid and joined once more into the Hastings – Charing Cross route. With this infrastructure in place, more effective use could likely be made of the available capacity on the Tonbridge Main Line with services operating in a loop between London and Tunbridge Wells via Oxted and Sevenoaks in both directions.
The current restrictive necessity to turn-back trains at Tunbridge Wells station (Hastings line) would be removed and other operational benefits/opportunities would arise.
With BML2 there would be the opportunity to provide direct services to Canary Wharf (also access to the City with Crossrail) from Tunbridge Wells (West). Such attractive services would release capacity on the Tonbridge Main Line.
Ultimately, reopening Tunbridge Wells (West) as part of BML2 is the only feasible way of providing West Kent with more capacity into London and relieving the Tonbridge Main Line. Other benefits accrue with the ability to restore direct services between the Tonbridge/Tunbridge Wells area, the City of Brighton and the Sussex Coast.