Research On The Spatio-temporal Accessibility Of Medical Services For The Elderly Using Ga2SFCA Method

China is one of the countries with the largest number of elderly people and the fastest ageing population in the world,and currently it has become a fast-aging society.The total population of the elderly people has reached 250 million,and the ageing rate was 17.9%by the end year of 2018,the average annual growth was about 8.59 million in the past five years.The rapidly expanding elderly population heralds an unprecedented social phenomenon,and some corresponding social problems need to be solved.One of the critically important issue is medical services for the elderly(MSE).In the face of the increasingly serious problem of supporting old adults,the Chinese government has gradually paid attention to the medical services problem of the elderly,and implemented a proactive ageing policy under the situation of "grow old before getting rich" and proposed to realize "Providing high quality medical services for all the old people".In fact,this slogan reveals not only the problem that the elderly can afford to get medical services and treatment,and not the problem of speeding up the construction of elderly health service facilities such as hospitals and nursing homes,but the problem that ensuring the spatial equality for the elderly to get medical services.Spatial accessibility is one of the criteria for measuring the equality of regional medical services,which provides a theoretical basis for the allocation of medical facilities.Therefore,it is important to measure the accessibility of medical services to the vulnerable groups of the elderly population in the context of ageing.In this paper,we take the downtown elderly population as the research object,and take spatio-temporal accessibility of medical services as the research content.The downtown of Wuhan city is selected as the study area,and the minimum scale is the community unit.Based on the accessibility value,multi-scale and multi-temporal evaluation of the equality of medical services for the elderly have been conducted from macro to micro level.First of all,we analysed of the urgency and necessity of solving the problem of MSE's spatial inequality in the background of the accelerated growth of population aging,and summarized the shortcomings of previous accessibility studies on the setting of road speed parameters,then,the literature research method(LSM)and questionnaire survey method(QSM)was appiled to study the characteristics of supply and demand,as well as the activity of MSE.Afterwards,the multi-source data included traffic big data,geographical survey data,socio-economic statistics and field survey data are combined,and the traffic cost is measured by the minimum time calculated by the O-D time cost matrix.Meanwhile,a Gaussian function was applied to improve the conventional two-step floating catchment area(2SFCA)method for measuring the accessibility of MSE.At last,time-frequency distribution and spatial distribution characteristics of the accessibility values at four different time periods,namely,the morning peak,the afternoon peak,the late peak and the peak period of the working day and the non-working day,were compared and analysed.Meanwhile,Houhuyuan was selected as a typical aging community for case analysis.The main conclusions are as follows:(1)According to the results of field research,the bus is the prior selected transportation vehicles for the elderly to get to hospitals in downtown Wuhan,followed by private cars and walking.(2)The number of communities and elderly populations under different time thresholds are different in the four periods of early peak,and the greater the time threshold,the higher the accessibility value.Espeacially,there existed a significant expansion effect on the spatial accessibility value during the working day as the time threshold getting larger.(3)With the increase of the time threshold,the high-accessibility area of the downtown Wuhan has a spatial transition from "dual-core" to "multi-core" and then to the dispersed distribution pattern.(4)The study of typical case studies could provide methodological and theoretical guidance for portraying the dynamic medical accessibility of specific communities and selecting the best medical pathway.