تحليل شاخص دسترسي در كلان شهر مشهد

Accessibility Analysis in Mashhad metropolitan

فاصله بين محلّ كار و فراغت در زندگي شهري، يكي از مسايل مهم در برنامه‏ريزي شهري است و كاهش آن از طريق جلوگيري از گسترش افقي شهري و تحقّق فرم كالبدي فشرده در قالب كاربري تركيبي امكان‏پذير است، كه نتيجه آن كاهش طول سفرها ومصرف انرژي، سرانجام كاهش آلودگي هوا و محيط زيست است. بنابراين دسترسي مطلوب يك عامل ضروري براي تحقّق توسعه پايدار محيط زيست شهري است. هدف اين مطالعه سنجش شاخص دسترسي و شناسايي نقاط قابل دسترس نسبت به محيط مجاور در نواحي شهر مشهد است. روش كار براي دستيابي به اين هدف، شاخص دسترسي با مدل گرانشي فرصتي هنسن (تعداد جمعيت (سرشماري 1385 و مسافت بين نواحي) است كه در 40 ناحيه شهرداري مشهد با ابزارهاي نرم افزاري Matlab 7، ArcGIS10 محاسبه شده است. ميانگين ضريب شاخص دسترسي برابر عدد 5/727 مي‏باشد كه حداكثر برابر عدد 1038 و با محدوده مركزي شهر مشهد (پيرامون محدوده حرم مطهرحضرت رضا(ع)) منطبق مي‏باشد. حداقل ضريب دسترسي برابر عدد 320 محاسبه شده است كه با محدوده هاي پيراموني(حاشيه‏اي) كلان شهر مشهد منطبق است. اين اعداد نشان مي دهد كه مشهد به لحاظ شاخص دسترسي به سه منطقه: 1- منطقه با دسترسي بالا (محدوده مركزي شهر) 2- منطقه با دسترسي متوسط(محدوده مياني شهر) 3- منطقه با دسترسي پايين (محدوده حاشيه‏اي و بيروني شهر) تقسيم شده است. همچنين نتيجه سنجش رابطه بين شاخص دسترسي و جمعيت در سطح نواحي شهرداري مشهد با نرم افزار SPSSنشان مي‏دهد كه اين رابطه منفي و برابر r = - 0/32 و در سطح اطمينان 0/5 معني‏دار مي‏باشد؛ يعني با افزايش ضريب دسترسي، جمعيت نواحي شهري كاهش مي‌يابد. همچنين بيانگر اين واقعيت است كه مناطق پرجمعيت شهر كه بيشتر شامل مناطق كم درآمد نيز مي‏باشد، داراي ضريب دسترسي پاييني است. افزون بر اين ضريب دسترسي با فاصله از مركز شهر مشهد به سمت نواحي پيراموني كاهش مي‏يابد.

Extended abstract 1- Introduction One of the major problems in urban planning is the existing distance between work and leisure in urban life. Preventing the expansion Sprawl through the city in the form of mixed users is possible, thus reducing the energy consumption rates and the length of journeys and finally reducing air pollution and the environment. Therefore, an essential factor for achieving good access to urban development, environmental Sustainable. The aim of this study was to determine access areas available to identify the areas surrounding the city of Mashhad. Access research nearly half a century, particularly after the release of a small model of Hansenʹs(Hansen,1959) about it. Dominate of suburbanization after World War II in the widespread use of car trips a day between work and life, particularly in urban areas by the mid-1970s, led to the marginalization of the Access issues (Newman, et al:1999). Most efforts have focused on the issue of Accessibility was to movement. 2- Theoretical bases Methods studied in in this research is descriptive and analytical. To index calculation the Mixed use of access to various software (MATLAB, ArcGIS and SPSS) based on 1385 population statistics are used in Mashhad 40area Mashhad municipality in 1385 was 40 areas. Initial attempts were made to measure the interaction between the two areas. 1 - To calculate the distance between the centers of districts (40) 40 x 40 matrix of the distance between them was calculated using Arc GIS software Centroid. 2-After calculating the distance between the centers of the regions, the interaction between them was calculated. In this stage, using the formula above attractions _ housing census of population 1385 as attractions (Sj) _ the distance between the regions (dij), in order to calculate the interaction between regions (Aij) provided. Varying definitions of access and consequently various patterns of measuring methods have been proposed by researchers. Accessibility as "freedom or ability to satisfy basic needs for the people preserve their quality of life is defined. Or access is, "easy to reach destination" or "cost reduction destination". While moving "easy transfer" or "cost per kilometer" _ increase the speed _ reduce the time between origin _ destinations defined. Definition of the meaning of Accessibility is freedom or the ability to access people’s an essential needs _ provided to preserve quality of life (Lau & Catherine CHCiu 2003,197). The access of relative closeness or adjacent location to another (local) is defined. (Tosou, et al, 2005, 426). Various methods of measuring accessible to Neilʹs theory is based on three Pasaogulari including: 1- Theoretical distribution (decentralized) 2 - adjacent 3 - road and accessible out to each one of them has a specific measurement method (2004, Nil Pasaogullari). 3-Discussion The spatial distribution of population in the city of Mashhad, shows the spatial inconsistency. And densely populated areas of the Northeast, but as the north-west and south east and low population densities are low. Analysis was performed to demonstrate the fact that the center of population and geographical area Mashhad central city and the metropolitan area is located in accessible. The results of the model show high accessible factor analysis of the accessible of the city, Mashhad range compared to surrounding areas. With increasing distance from the city center to the periphery is reduced coefficient accessible. The mean coefficient of Mashhad _ accessible at 40 Areas the maximum value is 727.5 the 1038 and the central city of Mashhad (around the holy shrine of Imam Reza is consistent. Minimum number of 320 was calculated coefficient access and the peripheral (marginal) in Mashhad. Accordingly Mashhad can access the index of three regions 1- regions with strong access (Central area) 2 - in the medium access (mid-range Mashhad) 3 - areas with poor access (_ marginal and out of the city) be divided. Measuring the correlation between the level of access and Mashhad areas shows that the negative relation R = -0, 32 and a confidence level of 5% is significant, but not strong. With the increasing Accessibility factor, the population of the urban area is reduced. And indicated the fact that areas with high population with low coefficients are Accessibility. 4. Conclusion & Suggestions Analyzing the spatial distribution of coefficient accessible in the city of Mashhad, indicating the difference between the different areas of _ is 320.15 points. Due to the geographic center of the overlap regions with high availability, historical, religious and commercial city of Mashhad, with minimum distance and maximum access to the benefits of increased focus in this area, the gravitational force that attracts people of this area has been from day trips. Due to the weakness of the public transportation systems (rail, Tramway and bus) down thousands of private vehicles in the area, causing traffic congestion and air pollution problems, and the environment in this area is sound. In addition to the above results to determine the availability of Mashhad indicate of monopole of the city. One of the central core of the city public transportation system with fast (train) are not to be confronted with the problems of traffic congestion and so on. Accessibility indicators suggest that the analysis of the spatial distribution, the transition from monopole of the central pattern multicenter. The center could rival sub central city of Mashhad, which has reduced the availability of suitable pressure on the core will