An Urban Design Framework for Qom City Center Applying Legibility and Imageability Approach

Population growth and its impact on urbanization have led to drastic transformation in traditional context. Urban centers as economic and social magnets are subject to change through new constructions frequently. Such rapid changes has made the structure of cities and its physical organizations unresponsively illegible leading to the imageability weakness. Lack of city center legibility and imageability results in ambiguity of these centers and problematic wayfinding towards significant elements. Understanding the urban environment is a mental process that takes place through the relationship between man and his surroundings. The image of the city is meaningful in the interaction of a network of people and places. According to the definitions of legibility and imageability, the user, in legible and imagieable environments, are easily able to categorize important and unimportant places, familiar and unfamiliar affairs, and more easily the main structure and sub structures of the city. Indeed, the qualities of variety, identity, as well as the clarity of relations between the elements can help people to perceive urban environment with clear image linking new and existing elements to each other. This paper aims to identify and assess the perceptual components to improve legibility and imageability and to provide a framework for legibility and imageability quality indicators in three visual-perceptual, spatial-physical and functional layers based on theoretical frameworks. Then, applying a descriptive-analytical method, the legibility and imageability of Qom city center as a case study would be assessed. For data collection, methods of observation, interviews, and cognitive mapping were used. For analysis, space syntax technique, SPSS technique, mental Map Assessment techniques were used.The results of the investigation of cognitive maps show that a number of mental maps do not include the desired complexity and high information. This showed that at micro level the sub structure in the minds of people had average legibility and legibly effective elements are needed according to the trained observer viewpoint. In reviewing the overall structure, half of the cognitive maps have a pattern and structure leading to a correct orientation. Also, the majority of people have identified the position of the signs, nodes and paths correctly, so it can be concluded that identification at the large scale is in adequate condition.Comparing the cognitive maps and space syntax analytical maps, the relationship between the integration value of paths in the cognitive maps has been evaluated and the results of the survey indicate low correlation between these two indicators and no clear relationship between them. A number of paths with the highest degree of integration have a relatively low percentage of emergence in cognitive maps. Therefore, in order to integrate the structural paths of the old fabric of the city that are highly integrated, they must be cognitively emphasized integrating the main structural elements of the past city and the current space organization of the city to improve the legibility and imageability qualities.The most effective indicator for increasing legibility is the concept of intelligibility, defined by the statistical relationship between general integration and connectivity. In order to calculate the level of intelligibility, it is necessary to correlate between the two local integration indices and general integration (synergy).In correlation diagram, when the points are distributed in a linear and compact pattern with a certain density, it can be concluded that the range has a strong degree of correlation and therefore offer more intelligibility. On the other hand, if the collection of points is not dense and does not form a linear dispersion pattern, it can be described as an illegible region in general scale. According to the correlation diagram (statistical correlation between the two indices of local integration and general integration, it is observed that the range has a comparative legibility, but some of scattered points in the diagram indicate a lack of intelligibility in those points. When the slope of this diagram is closer to 45 degrees, the area is found more legible. In the studies, the slope of diagram in the correlation between local integration and general integratio n is close to 60 degrees. Therefore, the area in terms of the part and the whole relationship has good legibility and shows that the connections in the structure are correlated with the integration at general level. However, the correlation diagram between two connectivity and general integration indicators show that according to the slope of the diagram, the distribution of intersections and their distance from main structure in whole complex and in fact the depth of the intersections of the main structure have not been impressive in improving the legibility.