ارائه چارچوبی تحلیلی برای سنجش الگوی شبکه‌معابر: مقایسه تطبیقی محدوده‌های خود سازمان‌یافته‌ شهر تهران

فرم شهری نمایانگر ویژگی‌های کالبدی شهر و فرایندهای غیر کالبدی (اقتصادی، اجتماعی و سیاسی) نمود یافته در کالبد است و شبکه معابر یکی از اجزای مهم و پایدار آن محسوب می‌شود. این مقاله درصدد آن است تا با ارائه یک چارچوب تحلیلی و معرفی شاخص‌های مناسبی که وجوه مختلفی از الگوهای شبکه معابر را هدف قرار می‌دهند، امکان بازشناسی روش‌مند این الگوها را فراهم آورد و در این فرایند، سه بُعد پیکره‌بندی، ترکیب‌بندی و ساخت (که به‌این‌ترتیب با شاخص‌های توپولوژیک، ریخت‌شناسی و متریک متناظرند) را به کار گرفته است. نوآوری پژوهش را نیز می‌توان در دو جنبه به‌کارگیری رهیافت شبکه در مدل‌سازی (در مقابل توصیفات کیفیِ متداول در پژوهش‌های داخلی) و تولید چارچوب تحلیلی با انباشت مجموعه شاخص‌های متفاوت و متناسب با اطلاعات در دسترس، برشمرد. پژوهش پیشرو به تحلیل الگوهای شبکه معابر (که به دودسته خود سازمان‌یافته و از پیش طراحی‌شده تقسیم‌بندی می‌شود) در محدوده‌های خود سازمان‌یافته که بدون هیچ طرح از پیش اندیشیده شده‌ای طی زمان به وجود آمده‌اند (و عموماً بی‌نظم، تودرتو و پرپیچ‌وخم توصیف می‌شوند) می‌پردازد و ویژگی‌ها و قاعده‌مندی‌های مشترک حاکم بر آن‌ها و وجوه تشابه و تفاوت آن‌ها را ردیابی می‌نماید. به‌کارگیری چارچوب تحلیلی در پانزده محدوده مطالعاتی خود سازمان‌یافته در شهر تهران نشانگر آن است که نه‌تنها الگوی پیکره‌بندی شبکه معابر در تمامی محدوده‌ها با یکدیگر مشابه و از نوع t-tree است، بلکه تحلیل‌های تری پلات انجام‌شده هم موید تشابه الگوی ترکیب‌بندی و ساخت شبکه معابر در این محدوده‌ها علی‌رغم وجود برخی تفاوت‌ها است که از وجود نظمی مشابه اما پیچیده و پنهان در آن‌ها حکایت دارد.

develop an analytical framework for studying street pattern; comparative study of street network pattern in self-organized districts of tehran

introduction: the urban form can be considered as a set of elements of which the street network is one of the most important components. it is divided into two categories: self-organized and pre-designed networks. while the latter evolved by large-scale barriers of economic and social constraints in a short period of time, the former does not imposed by any central agency, but rather, sprouts out from the uncoordinated contribution of countless local agents during the time (jacobs, 1961). still today, self-organized street networks are often underestimated in their most fundamental values, and they are described as disordered (porta et al, 2006a) complicated, and convoluted; but, the identification of common features and their regularities has become a field of research. against this modernist stigmatization, some (like jacobs) argued that, unlike the euclidean geometry in the pre-designed networks, the marvelous complex order of the self-organized networks is not visible at a first glance. that order, is the order of life (jacobs, 1961) which is such a complex order that, is common among other non-geographical biologic, social, or natural systems. these claims led to a wave of studies from the early 1960s on the analysis of the patterns of the street network and its components using the graph theory framework, which sought to identify the characteristics of the street network of old self-organized neighborhoods and the complex order embedded in them. with this introduction, the current research has been done to find similarities and dissimilarities in street network patterns of self-organized districts that have emerged without any premeditated designs over time. this article also seeks to develop an analytical framework composed of different indicators that target various aspects of the street network patterns, to enable the recognition of these similarities and differences. for this reason, first, three concepts: 1) configuration, 2) composition, and 3) constitution has been distinguished in studying street patterns. then, the corresponding measures have been introduced and evaluated in 15 self-organized districts in tehran, which meticulously have been selected as case, and their street networks have been drawn. in the third stage, values have been compared with a three-plot analysis, and street network similarities and dissimilarities have been traced. methodology: the quantitative method is used in this research and to compare and analysis of the street network pattern in self-organized districts of tehran. based on the background of the research and theoretical framework, this comparison has been done using three types of indices which are 1) topological, 2) morphological, and 3) metric indicators which correspond to the three concepts of the street networks:topological indicators (corresponds to the configuration): refers to featuring links and nodes that are associated with abstract topology, which is related to the process of formation: their ordering (relative position), adjacency, continuity, and connectivity.morphological indicators (corresponds to the composition): refers to the absolute geometric layout which is related to the product of formation: absolute position, lengths, areas, and orientation.