Orbirail

On 12 February 2009, Mayor Boris Johnson and Transport Secretary Geoff Hoon announced £75 Million to fund the southern extension of the Overground network between Surrey Quays and Clapham Junction as part of the East London line extension, creating the final connection of an orbital railway for London to be completed in time for the 2012 Summer Olympics.

The benefits of an integrated transport system were unknown at this time and each main-line railway company built its own terminus in central London and operated radial routes from that point.

For example, Waterloo railway station in south-west central London is the focus of lines radiating out to the south and west.

These outer routes failed to attract the passenger numbers hoped for and were eventually cut back or ended while other, more radial services on the lines continued.

Throughout the 20th century London's railways operated on a radial model and the few remaining semi-orbital passenger routes withered, with the lines used mainly for freight services.

The idea of reviving and expanding the semi-orbital routes to relieve some of the load on central London in a more cost-effective way than the building of new tube lines was considered, coalescing around the suggested name "Orbirail", but it won few friends in the National Rail network for commercial and operational reasons.

During Ken Livingstone's term as Mayor of London, TfL exploited the potential in the neglected peripheral rail routes and started to plan a complete orbital rail system by joining these routes together (albeit with no plan for a single fully orbital service).

One of the limitations of the public transport network in outer London is the lack of direct and convenient orbital routes.

Orbirail's proponents believe that it would be a relatively low-cost project, involving only a small amount of new track, some improvements to existing lines and an increase in train frequency.

Poor interchange options are a general problem with most of London's older railways, which were built by competing private companies in the 19th century before the need for a coherent and integrated transport network was understood.