4.7 EntrapmentA person living in a low density neighbourhood may not wish to become part of a high density PT corridor. Over time, people who value living within the betterment levy / high density corridor can move in and people who value it less can move out. However, stamp duty and relocation costs make it costly for a person to move out to a neighbourhood they prefer,leaving them worse off – unless there is only partial value capture, leaving them with a partial windfall to defray the costs of relocating. There may need to be additional mechanisms to address this, such as an amnesty on stamp duty for those who want to relocate. The cost benefit analysis would also need to survey residents on their valuation of living in a high density PT corridor, to ensure any loss of amenity – of having higher densities retrospectively imposed – is included in the cost benefit analysis. These issues are less acute for greenfield developments – such as a new transport corridor that opens up a greenfield area of new suburbs – rather than providing new infrastructure to existing suburbs.