A Methodology for The Image of the City

In The Image of the City Lynch defined a concept of imageability or legibility of the physical form by the pattern or structure of the interrelations among five elements. The well-known elements are: paths, edges, districts, nodes, and landmarks. When considered in pairs (for example, paths — nodes, paths — districts) Lynch noted the elements could strengthen or weaken, ‘reinforce’, or ‘destroy’ each other. The seminal study method, however, deemphasized the interrelations of the elements, critical to the observation of how a ‘complex visual whole’ is organized. To surmount this limitation a method is presented which aids in the measurement of the interrelations of Lynch's elements. Formally, the pairwise comparisons of the (five) elements are performed by means of Saaty's square, a reciprocal matrix with unit rank whose eigenvector solution gives the priority or the relative importance, or dominance, of the elements on a ratio scale. The inputs to such a matrix are provided by means of a questionnaire which solicits each field surveyor's perception of the relative dominance of the elements within each pair by using a nine-point scale. The proposed protocol is applied to an analysis of the image of a university campus as seen in the field by a group of surveyors. The new approach retains the essentially qualitative conceptual property of Lynch's near-classic methodology while allowing for a statistical quantitative account of observer variation and group consensus of the image(s) of structure.