Urban Streetscape Quality in Tehran Metropolis

Introduction
With the emergence of new concepts in massive urbanism and architecture of new millennium, such as quality of urban life, green urbanism, healthy and walkable cities, and with the competition of different cities around the world in order to enhance urban livability, one of the issues addressed in the meantime is improving urbanscape by organizing and identifying urban streetscape and providing vitality of urban streetscape. Necessity of incorporating this issue into Iranian Urbanism is due to the rise of modernity, modernization and modernism over the past decades as well as because of the lack of any comprehensive approach of improving historical streetscape felt more than ever before. Accordingly, this paper is aimed to first develop comprehensive streetscape indicators and present standard framework of streetscape assessing and measuring using "Meta-Analysis" research method based on explaining and analyzing of Iranian and international researchers’ theories and domestic and international experiences. Next step in this research is measurement of urban streetscape quality in Tehran Metropolis with a focus on the subjective approach of citizens based on measurement of 60 streetscape indicators in target streets. Thus in this paper, the comprehensive streetscape indicators has been developed and standard framework for assessing streetscape and measuring quality of urban streetscape in Tehran Metropolis has been presented. Selected approach for selection of measurable indicators is subjective approach. For this purpose, at first, basic definitions and concepts of streetscape have been reviewed and after that, theories of streetscape researchers have been discussed in two sections of Iranian and International theories. Then, in next section of this paper, most important experience of urban streetscape in different cities has been reviewed, streetscape indicators from scientific and professional points of views are extracted and, finally, theoretical formulation and specific streetscape planning and design indicators are discussed. Then, based on relevant indicators, three streets have been tested using purposive sampling. Accordingly, streetscape quality from residents’ point of view is evaluated based on average satisfaction with indicators in each of target street and, finally, last section of this paper discusses the measurement of streetscape indicators in three target streets and then final conclusion of this study is attempted.

Materials & Methods
Due to the mismatch between formation roots and western concepts, when it comes to the study of streets in Iranian urbanism, it is essential to consider Iranian researchers’ ideas in this field in addition to world researchers’ viewpoints on streetscape. Therefore, in this paper, we have tried to exploit theories of Iranian researchers worked in this field whom are mentioned in references and throughout research process in order to comply with Iranian culture and environment. Besides, western researchers are cited for extraction and documentation of common indicators existing in international research literature. It is worth noting here that in addition to the roadway surfaces, street scale and its functional realm are also meant within pedestrian space included in this urban space. Accordingly, street in this paper means urban space where cars move easily and, at the same time, appropriate space for movement and other civic activities by pedestrians is provided. In this way, first, once streetscape and basic concepts are brought up and theories and viewpoints of Iranian and international researchers and major domestic and international experiences on streetscape are considered, using “Meta-Analysis” research method, comprehensive streetscape indicators are developed and a standard framework is provided for streetscape evaluation. Following this, streetscape indicators in three streets are measured. Weighing criteria of relevant indicators is arithmetic mean of relevant indicators considered by citizens which include 300 people according to Neiman sampling.

Discussion of Results
In this paper, in order to identify and document streetscape dimensions, criteria and indicators, first, definitions and concepts of urban streetscape is considered and then theories and thoughts on streetscape in 30 Iranian and international studies are refined, authors of which were selected considering citing frequency of their studies in related major scientific papers. In the following section, the most important domestic and international experiences on urban streetscape are discussed. The aim of this section is to find a theoretical framework to extract streetscape dimensions and indicators by reviewing experiences of major streets in the world. The difference between this section and last one is that it tries to extract streetscape indicators from scientific and professional experiences viewpoint in a sample of most important cities of the world. In order for this, 18 successful domestic and international experiences are reviewed and relevant studies are analyzed focusing on dimensions and indicators of streetscape. In the next section of the paper, general streetscape indicators are summed into 706. Following this, common indicators provided by Iranian and international researchers and also domestic and international experiences of streetscape were omitted and then, final indicators of streetscape in particular and in accordance with Iran conditions were extracted considering 4 following requirements: frequency of each indicator, selecting subjective indicators based on study’s objectives (focused on subjective indicators), selecting measurable indicators (measurability through questionnaire), and urbanism and worldview conditions of Iran. Regarding this, 60 streetscape indicators in particular and according to Iran’s conditions based on these requirements are extracted from general indicators and are provided as supermatrix of specific streetscape planning and design indicators in Table 1. This supermatrix has been formulated in two parts including: Iranian and international theories and domestic and international experiences. Iranian and international researchers and domestic and international experiences are placed in 48 columns and streetscape indicators are placed in 60 rows.

Conclusions
In this paper, comprehensive streetscape indicators were formulated and a standard framework was provided to evaluate streetscape and measure urban streetscape quality which has been a major urban planning and design priority during recent years. Besides, streetscape quality from citizen’ point of view was evaluated based on average satisfaction with indicators. As research literature review in developed countries shows, improving streetscape results in better environmental quality and desirability of streetscape and image of city and eventually, urban competitiveness. Therefore, street planning and design guidelines in Iran focus on traffic and geometric conditions of streets. They considered objective indicators where less attention was paid to specific streetscape indicators from urbanism and subjective indicators point of view. On the other hand, in Iran, there is no comprehensive framework of streetscape to be taken as manifesto or guideline of action. In this regard, there is no criterion and indicator for evaluation of desirability or undesirability of streetscape as the most important component of urban form. This paper, first, formulated comprehensive streetscape indicators and then provided a standard framework for evaluation of streetscape. This step was carried out in two parts including refining the theories of important researchers on streetscape considering domestic and international opinions and refining the most important and successful international experiences. Eventually, 60 main measurable streetscape indicators were documented focusing on subjective approach and based on particular urbanism conditions in Iran and they were provided considering researchers and relevant indicators in the form of supermatrices of indicators and theories. In the following section of this research, first, a questionnaire was formulated based on indicators extracted from former step and then purposive sampling and determination of sample numbers were carried out, based on which three target streets were selected and in the next step, based on the questionnaire, data was collected in target streets, which was tested and refined according to research topic. Finally, each indicator in each street was studied and the existing situations of target streetscapes were compared. By reviewing general condition of target streets which include their social, physical and environmental conditions, it was found out that Naser Khosrow street with 2.7 scores, stands in top, Valiasr Street with 2.6 scores stands next and eventually, Enghelab Street with 2.2 scores is the last in rank. Social, physical and environmental condition of none of the streets was considered by local pedestrians and residents in average level of satisfaction.