An Optimum Location of Public Parking in the C.B.D of Iran Cities (Case Study: Central Business District of Tabriz City)

1. Introduction
When created, new services need spending considerable costs. Therefore, recognition of the best optimum sites for these kinds of centers so that all citizens benefit from its services is much important. In terms of urban planning, parking demand increase is diagnosed as a result of increased demand for vehicle travel. Hence, distribution of urban land uses will determine parking distribution demand where travel demand occurs. Public parking as one of the most important parts of transportation system play prominent role in reducing traffic load. Optimum site selection for parking spaces not only increases its efficiency, but also causes reduction of marginal vehicle parks and, therefore, it causes traffic fluency and wider streets.
By the increase of population and expansion of Tabriz city and also an increase in the number automobiles especially in 2001 on one hand and the lack of attention to the subject of parking along expanding road network in urban transportation on the other hand have caused many intensive traffic problems for citizens. Existence of many historical monuments such as traditional bazaar, Alishah Ark, Edifice of Tabriz municipality, Historic bath of Nobar, Mashrute Edifice, Main Mosque, Imam Khomeini Feast and also some other historic, religious, political-official centers in central tissue of Tabriz city has also made researchers to determine appropriate sites for establishing parking lots by using integration of various methods.
2. Materials and Methods
This is an applied research with the main approach of Descriptive-Analytical. The tool that has been used for modeling and analysis is GIS software. In order to rule out limited areas for establishing public parking, a model should be used that assign zero value to those limited areas. Therefore Boolean logic was used thorough integration of limitations and then final map of limited areas was extracted. Subsequently and after omitting limited areas, appropriate sites were selected by integrating three techniques of AHP, FUZZY and TOPSIS and overlapping desired layers. In this regard, Expert choice software for weighting in AHP model and also Excel software in order for calculating were used. Finally, Arc GIS 9.3 software was used for analysis and overlapping of layers. The included criteria at this study are distance to travel centers, crossing traffic, appropriate sites for establishing parking, and land value.
3. Discussion
3.1. Using Boolean logic
By using this logic limited areas such as traditional bazaar and so on were omitted. Given the resulted map, it is observed that blue colored sites are identified as limited areas that establishment of parking is not recommended in these areas.
3.2. Integration of AHP model and Fuzzy TOPSIS
At this research, Triangular Fuzzy numbers were used in Fuzzy TOPSIS. After calculating and converting variables to triangular numbers, these numbers were multiplied by AHP weights for achieving fuzzy weights. The resulted AHP weights for each of the criteria include: Land use consistency has a weighting of 0.168, Land value 0.094, Crossing traffic 0.18 and finally distance to travel centers has a weighting of 0.558.The resulted weights were multiplied by triangular numbers including 5 matrixes (Fully consistent, relatively consistent, middle, relatively inconsistent, and fully inconsistent).
After formation of decision matrix by using fuzzy numeral components, the distance of each criteria of parking site selection from positive Ideal and negative ideal was calculated using TOPSIS technique. Thus, for each criterion, the distance information layers from positive and negative ideal were created. Then, by combination of positive and negative ideal layers to each other in GIS environment, the output was a final layer according to which ultimate options were prioritized was done.
4. Conclusion
Currently site selection of parking is done by using old methods. The methods do not have capability in the use of all effective factors anonymously and are much time consuming. These are the main deficits of old methods and these problems cause deficiency in established parking structures. In order to get far from mentioned deficits, the appropriate methods should be recommended and then be replaced. In this regard final objective of this research is presentation of an appropriate model for the optimum site selection of public parking in historical and business center of Tabriz city. Generally, each selected point at the study area will be in suitable condition in two levels in terms of access to main road networks and reduction of traffic load resulted by parking establishment. These points are in high-traffic areas, because selected areas are highly centralized by various trades and official land uses. According to the implications of the above statement, the following cases should be considered as final results:
1. Given the integrated use of fuzzy and classic decision-making methods in the procedure of site selection, more flexible condition has been made and finally the best result was observed.
2. In the process of parking site selection, the distance between parking and travel center is an important factor; therefore, it should be noticed at various points of study area where there are highly density and necessity of establishing parking, some appropriate sites should be selected to establish parking.
3. Results depend mostly on the condition of study area and various methods of site selection. Thus, various methods may present different results in different areas and regions. Therefore, the best method always considers situations and limitations and then presents the best strategy.