I am currently researching this area of law in response to to recent challenge to a Piece of South African legislation. The legislation in question is fairly recent and it elevates road design plans to a status that it did not enjoy under the old legislation. It effectivley freezes an owners land which falls within a road design.road reserve. It prevents rezoning, subdivision etc. It assumes that all environmental and public particiaption procedures were followed. It does not not guarantee that the road will even be built. Only when the government proclaims the road, is expropriation deemed to have occured and compensation will follow.
What is in issue are the relevant land owners rights to property (consitutionally guaranteed) and the need for public planning.