THE APPRAISE OF ACCESSIBILITY ON THE EVOLUTION OF HIGHWAY NETWORK IN HUNAN PROVINCE

Based on the shortest path matrix,the author calculated the accessibility of the highway network in Hunan province in 1984,1993,2004 and 2025.The paper gets the result: the cities in the highway network turn out the obvious core-periphery model with velocity index.The best accessibility is in the Mid-south of Hunan province and the accessibility's circle is homocentric.The direction of the accessibility' change is distinct from northeast to southwest.In the process of highway network evolvement,the accessibility' improvement follow the 1aw of diminishing returns of scale.The cities in the northwest and south of Hunan province are the worse.In the beginning of the highway improvement,the associated coefficients of variation(CV) have been larger.In the end of the Hunan freeway network construction,the accessibility will be in balance.In 2025,the most cities can be reached within four hours in terms of the 14 cities at prefecture level,with more cities can reach the circle of the two hours' intercommunion of the core region,the regional integration progress will be quicken.