Innovations in measuring density: From area and location density to accessible and perceived density

Although density has been an important concept for urban design and planning ever since the 19th century, it is an imprecise concept with varying definitions and measurements. This is annoying as the concept is central to strategies for sustainable urban development which have gained wide support since the 1990s. This paper gives a brief review of the most frequently used urban density measures and their shortcomings. In this paper, we will further show that a multi-variable definition of density as proposed in the Spacemate method is needed to capture important morphological qualities that otherwise are lost in abstract numbers. The paper also addresses the Modifiable Area Unit Problem inherent to all measures of urban density, and proposes to solve this by introducing accessibility in the density measure. Defining distance is obviously a critical part of the accessibility measure and it is therefore proposed to use the axial map developed in space syntax, to measure distance. The axial map is a geometric representation of urban space based on graph theory, constructed from the point of view of a cognitive subject, i.e. an experiencing and acting human being. By doing so this paper arrives at a measure of accessible density that even can be understood as a measure of perceived density