Evaluating infill development capacity in city center of Tehran

Introduction
New urbanization evolution in the world and emergence of new urban problems make downtown areas in adverse effects of urban development more than other urban areas. In the third world cities, due to rapid urban growth, influx of immigrants, lack of planning, etc... Problems of downtowns appear more sever which sometimes pose a national issue. The old neighborhoods not only are considered as the memorial of culture and city history but also as an investment which can meet present and future needs of residents.
This attitude towards old neighborhoods, assume that these areas have abilities and potentials such as infrastructure, vacant land and abandoned building which have the capacity of reuse and redevelopment. As a result, planning for redevelopment of these areas is essential case in most cities.
Infill development can be associated with development of urban centers, where such projects are used to restore city center neighborhoods. In fact infill development could be proposed as a response to sprawl, a process which makes urban centers remain stunt and away from urban development.
The first step towards infill development is finding a method to measure development capacity, so using an appropriate approach to evaluate the development potential is essential. One of the references in measuring development potential is Solimar research group which analyze and evaluate infill potential development broadly.
The question that study is formed around is: "Does the capacity development measurement in Tehran’s city center reflects that it has lands with redevelopment potential?" This study is aimed to evaluate infill development potential in Tehran’s city center. This evaluation is based on criteria which derived from theoretical and empirical literature on subject. After introducing infill development’s indicators, it’s time to evaluate theme in region 12. To achieve this issue by using Geographic Information System (GIS), prepare layers of indicators, overlaying criteria layers, then by using analytical hierarchy process gives priority to divisions of region 12.
The results indicate that all six division of the region 12 have capacity of development and among these six divisions, division 3, 2 and 4 have the highest rank.
Materials and methods
Research material
Region 12 of Tehran city including historical core of Tehran. Center of Tehran as a focus of city, and center of trading, business, aggregation of social, cultural, religious activities is referred as correlation core.
Tehran’s city center‘s area is about 1600 hectares. Region 12 consist of 6 divisions and 23 neighborhoods. 27 percent of this region has 400-year history and 73 percent of that has over 200-year history. Despite these values, over one third of this area is depressed and out of work. In fact the historical center of Tehran is increasingly vulnerable and in a process of deterioration.
Research method
The method of research is descriptive, and data collection method is document review and library studies. Document review and library studies include surveying data, books, journals, articles, urban plans etc. … Data collection resulting in research theoretical frame work and deriving research indicators which are used in development capacity assessment.
Geographic Information system (GIS), Microsoft Excel, Analytical Hierarchy Process and Expert Choice are used in analytical section for analyzing quantitative indicators of research.
Discussion of results
.Population density criteria: Low population density has a high potential for development. Among the divisions of region 12, division 1 and 2 have the lowest population density in the area. Dominant land use of these two division is business zone. Due to dominant use and lower rate of residential use in these divisions, population density is the lowest among the divisions.
. Land Criteria: Land criteria include three indicators: vacant land, abandoned area and brown field. In city center of Tehran vacant land include around 56 hectares, abandoned area 46 hectares and brown field around 160hectares, and the most concentration of these three indicators are in the division 3.
. Building Criteria: This criteria include two indicators: quality of building and floors of building. Quality of building, include buildings and lands which encompass destructive structures. Among these 6 divisions in region 12 of Tehran, division 3 has the most areas with low quality of buildings.
Floors of buildings used as an indicator in assessment of development capacity. Low story Buildings can be considered as a development potential. Tehran city center unlike other downtowns around the world has a very low height. This suggest that Tehran’s downtown has great potential in terms of development density.
. Access to public transportation criteria: Access to public transportation is a basic feature of a successful infill development. So blocks and parcels with convenient access to public transportation are considered as a potential development. Access to public transportation criteria has two indicators: access to bus stations and access to metro stations. Assessing these two indicators represent that approximately most of the area has an appropriate access to public transportation stations.
. Regulatory criteria: This criteria is covering five indicators: redevelopment lands, stagnant areas, high density zones, residential zones, mixed-use zones. These five categories are mentioned and determined in Tehran comprehensive plan and region 12 detailed plan, and in this study, they are used as development capacity. In region 12, 9 parcels with 33 hectares area allocated to redevelopment land. In this category, division 4 has the most concentration of redevelopment lands.
The total area of stagnant area in region 12, is about 641 hectares and division 3 has the most stagnant area in the city center of Tehran.
According to master plan and detailed plan zoning, about 574 hectares is allocated to high density construction. Due to historic characteristic of division 2 and 3, in order to preserve and maintain valuable building, lack of high density zoning in these two division is acceptable.
Residential development is a main element of infill development which cause revitalizing and returning population to city centers. Among these 6 divisions, division 5 and 6 have the most potential of residential development in the region.
Mixed use development is a principle of infill development in order to enhance livability of neighborhoods. Division 1 has the most potential of mixed use development in city center of Tehran.
After preparing layers of criteria and indicators and overlaying them, it’s time to ranking these 6 divisions to find out which of them has the most capacity of development in the area. Using Analytical Hierarchy Process through Expert Choice software showed that among 6 division of region 12, division 3, 4 and 2 have the highest potential for development.
Conclusion
In this study, surveying and analyzing infill development criteria and indicators in city center of Tehran represent these results:
. Population criteria shows that region 12 has a low population density so this area has a potential to attract population.
. Surveying land and building criteria indicate that the city center of Tehran have areas with capacity of development, also it reflects high dysfunction and deficiencies in the region 12.
. Access to public transportation criteria indicates that the whole region has the appropriate and convenient access to public transportation.
. Surveying and analyzing urban plan regulations shows that these regulations not only act as a deterrent to development but also they include development capacity.
. Assessing and evaluating development capacity in region 12 indicate that all divisions have five introduced criteria but in different proportions. And ranking results showed that division 3 has the highest capacity of development among 6 divisions.