The Research Of City Comprehensive Accessibility Based On Internal And External Links In Dual-nuclei Region

Traffic accessibility is an effective index to measure the development degree of regional traffic network,and it is also an effective indicator to evaluate the potential of regional economic development.It is one of the internal driving forces of the change of regional spatial structure and economic development.In the process of industrialization and urbanization of the country,the traffic network construction have the important meaning on improving regional transportation network,enhancing regional transport capacity,strengthening regional economic linkages,improving the regional accessibility level,enhancing regional competitiveness,and coordinating regional development.The model of regional dual-nuclei structure is widely found in the coastal provinces of China,compared with the single central area,the traditional method of accessibility measure based on regional contact can not reveal the traffic advantages of the portal city.Based on the ArcGIS platform,the paper combined regional accessibility and external accessibility to find the improvement program which can comprehensive evaluate city traffic accessibility and reveal the space-time evolution characteristics of the city comprehensive accessibility in Liaoning province with 1986,2000 and 2013 as time section.The results showed:(1)The method that measures external accessibility has a certain error correcting function to the phenomenon that internal accessibility relies too much on the geometric center,and combining the internal and external accessibility is an effective way to improve the traffic accessibility evaluation.There are obvious differences in distribution and formation of internal and external accessibility,and then divided the comprehensive accessibility into extroversion type,balance type,transitional type and introversion type.The distribution of external accessibility mainly associated with the proximity of high-grade traffic facilities and spread out with center and gateway cities.(2)Putting forward the concept of “accessibility location impedance ability”.The ability of city transfer adverse inner traffic location reflected by the accessibility location impedance coefficient.(3)The dual spatial structure of Liaoning made the internal and external accessibility shows obvious spatial differentiation phenomenon.The gateway city must firmly grasp theleading power of regional transportation system change and network optimization to prevent its traffic advantage from losing and became the real edge area.(4)Calculated the urban economic contact intensity with linear distance and accessibility and made a comparison between them.The impact of the accessibility to the economic contact intensity can be divided into three types of promotion,coordination and restriction.