عنوان مقاله [English]
Historic districts are one of the most precious elements of the cities, which have been unwantedly neglected in the process of urbanization revolution. This has dramatic consequences on the identity of the fast growing cities. These areas are the essential elements for preserving the characters of the cities and play a substantial role in urban activities by providing great social interactions. In the last decades, the fast growing population and rapid developments of the cities caused some undesirable problems such as heavy traffic streams and social-environmental issues. These side effects are more critical in the historic districts which are usually located at the central parts of the urban areas and play a significant role in preserving the identity of the cities. Hence, in recent years, urban management has paid attention to this endanger regions in order to sustain and enhance their properties by introducing some plans as urban regeneration policies which cover all sides of environmental, social and economic revitalization. On the other hand, two main characteristics of historic districts are the physical movement of pedestrians and traffic flow. The performance of these areas is highly vulnerable to
these subjects. To cope with the problem, more pedestrian-oriented and traffic-oriented trends are introduced in urban planning. Any interfering with historic districts as a kind of urban districts with special potentials and restrictions is a difficult and complicated issue, because the aim of interfering with historical districts is to create balance between
conservation and social- economic revitalization as a form of development. Certainly, no one can expect an efficient interference with historic districts without using efficient approaches and tools from other branches of knowledge. Strategic planning based on systematic approach principals is the outcome of Knowledge management advancements
for solving complicated subjects and problems. Therefore strategic planning has offered affective tools for enhancing the decision making process. Operation Research, as the recent approach of strategic planning, is pervading in many branches of science such as urbanism by using modeling and optimizing techniques. For example, locating Urban Facilities and land use planning are two applications of operation research in urban planning. Noticing that multiplicity and variety of urban variables in historical districts are more complex than other kinds of urban districts and based on sensitivity of historic districts, using operation research approach is the very essential and helpful method for providing an optimized interference based on all systemic and strategic planning principals. In this research, based on studying and considering the literature review on systemic planning, two points are extracted: first is the outside system connection that indicates necessity of analyzing the movement flow as the dynamic connection between historical district and surrounded areas, and second, is the inside system connection which is emphasized and suggests the modeling connections between affected variables such as quantitative urban planning indicators and qualitative environmental factors. On the other hand, four key points are achieved based on considering the principals of strategic planning: first is the vision making besides solving the current problems; second is identifying the several and various players with conflicting objectives having role in integrated regeneration process. Third is the determination of budget limitations and other limitations of historical districts and fourth is the necessity of flexible planning for offering optimum solution in probable situations in future. With identifying the keys of systemic and strategic planning and combining them into an integrated approach, two conceptual models based on operation research, are proposed. These models covering the various objectives of regeneration process with focusing on traffic and pedestrian flow network. Each proposed model is a bi-level model; upper level is a decision making tool for urban planners which can give output of the optimum budgeting plan for selecting the projects in public places, while satisfying the financial limits and constraints of the historic districts, and the lower level is a macroscopic traffic or pedestrian assignment model. In the other words, to come up with environmental, social and economic revitalization as urban regeneration projects, urban planners need to understand and analyze the behavior of the pedestrians and drivers in response to their environment and changes of urban network which is handled by lower levels of two conceptual proposed models. Creating logical connections between two conceptual models are the final step of this research. The integrated conceptual model observes all extracted foundations of systemic and strategic planning and is practically due to operation research principals. The final proposed model is applied to solve two real cases in historical context of Tehran. The results demonstrate on the superiority of proposed model in delivering the optimum scenario in regeneration planning.