Plan approval is a formal administrative procedure for the binding official approval of a plan. All public-law relationships between the project sponsor and those affected by the plan are regulated in a legally binding manner. Without planning approval, a large number of public-law procedures would have to be carried out for major projects, which would make efficient and consistent planning almost impossible.

In particular, the construction and modification of mountain railroads, overhead power lines from 110 kV, airports and airfields, gas supply lines over 300 mm, dyke construction and watercourse development, railroad lines, federal and state roads and freeways are generally subject to planning approval.