Investigating the Role of Permeability in Promotion of Quality of Environment of Neighborhood Unit (Case study:Tehran-Narmak)

Promoting quality of urban environment is one of the main and major responsibilities of urban planners and urban designers. Regarding this objective, creating strong linkage between urban design and planning is really crucial and it can lead to more executive results. In this article, the role of permeability has been emphasized as one of the main tools in promoting quality of urban environment in neighborhood's scale. There are so many contradictory approaches regarding permeability factor affecting parameters of quality of urbanenvironment, so in this article different aspects of permeability and their positive and negative impacts on the urban design qualityhave been monitored. Among positive impacts we can refer to promoting legibility, attraction of various and walkability accompanied by reduction in motorized vehicle usage which led to less energy consumption and air and noise pollution. The negative impacts are included decline of privacy and coziness in local spaces, decrease in social interactions and resident'ssense of belonging, domination of motorized vehicles on urban spaces, difficulties in climatic comfort and increase in visual pollution. These impacts are demonstrated by a model that shows interrelation of permeability and quality of environment. Since recognition of the ways of enhancing quality of environment via permeability criteria has been one of the main objectives of this research, in thefirst step, a complete and total literature review about permeability, quality of environment and their correlation has been conducted. Inthis special respect, qualitative research has been used and with emphasis on explanatory research, main dimensions and components of permeability were recognized that led to conceptual model and research framework. In second step, the assessment of the environment of life andpermeability in the chosen case study based on the theoretical framework performed. The case study is a well-known district ineast of Tehran, named Narmak, a regular planned zone with history of 60 years. It's distinguished plan thatcontains 100 local squares, extended in 600 hectares area and with population of about 400000 people. This district has anunique identity and has brought a strong sense of belonging to its residents that can be considered a neighborhood unit. Assessment of quality of environment in Narmak Region has been executed by a visual survey and filling questionnaires on the basisof 51 sub criteria. Research findings showed different zones with various quality of environment in this neighborhood unit. Oneof These zones that is dominated by commercial uses play an important and essential role in the area.,It has not yetcaused many problems regarding quality of environment, however, it has become mainly vulnerable and need to be focused more than the other parts. At last by using SWOT technique, some strategies for creating better permeability and promoting quality of environment in Narmak have been presented. The most important strategies concern the necessity of creating balance between pedestrian movement and motorized traffic, tranquility and vitality of environment, determining certain level of mixed-use activities, integration and segregation of various spaces of neighborhood unit and possibility of entrance to private spaces.