MSAs are not ‘footloose’, they can only be built alongside the Motorway that they serve. In this area the M25 runs through the London Green Belt. The means that the only way that the public safety and welfare need can be met is through development in the Green Belt.
Government Policy has a clear preference for ‘on-line’ MSAs ie not connected to the local road network or not located at a Junction. This is because they are more attractive to drivers on the Motorway and do not add traffic to the existing road network.
The number of potential on-line locations is constrained by the need to have a safety gap of typically 2km between the end of any slip road and the nearest next slip road.
Extra has undertaken an extensive search of potential alternative sites alongside the M25 – the best location is on the site of Warren Farm where an on-line MSA can be provided within an extensive, well contained and attractively landscaped area