Did the key projects add value due to the involvement of the
national government, and if so, which specific aspects of the projects
created this surplus value? In order to effectively reconstruct
the effects of national government involvement in the key projects,
we compared them with a number of reference projects (Fig. 3). A
number of reference projects were selected based on an overview
of large-scale urban redevelopment projects in the Netherlands.
For each generation of key projects, these reference projects were
equivalent in terms of (1) surface area of the project, (2) planned
volume of offices, housing and other functions, (3) functional mix
and (4) the complexity and number of actors involved. In contrast
to the key projects, the national government had no significant
involvement in these reference projects. The regional distribution
of the reference projects was also comparable to that of the key
projects. These criteria resulted in four reference projects for
the first-generation and three for the second-generation key
projects.