Research On Rationality Evaluation Of Road Network In Small Towns In Mountainous Areas

Mountainous small towns consist of central area and county area.Due to topographic factors,the layouts of cities and road network in mountainous areas are different from those of plain cities.Current road network evaluation and planning work in our country is based on Code for transport planning on urban road GB50220-95.Although the code gives network indexes,it only proposes road network indexes for large,medium and small cities.Mountainous towns are still a blind spot at this stage.With the promotion of the project "Pushing ahead with the construction of small towns",solving the traffic problems of small towns especially mountainous small towns can facilitate small towns to play a more active role in China's economy and society.Based on the situation,this research explores related issues of urban road network and county road network in mountainous small towns to study the rationality of road network,providing support for network planning of small towns in mountainous areas.Firstly,basic concepts of small towns and mountainous cities are discussed to form a comprehensive understanding of mountainous small towns,along with the characteristics of small towns and land layout of mountainous cities.Secondly,deep analysis on traffic characteristics of mountainous towns is made in the research.Based on the formation and evolution of the road network,this article analyzes the network structure and function of mountainous small towns.And a survey of the resident trip is conducted in Nanhua County,Yunnan Province to acquire residents'travel characteristics and traffic features of mountainous small towns.Then,road network indexes are divided into two categories:scale and structure.Combined with the features of the mountainous small towns,the calculation method of the density index of road network is improved and pedestrian density index is proposed.Also,non-linear coefficient and accessibility coefficient data collection and calculation method of road network system are discussed.Based on the principles,indexes are optimized for the establishment of the road network rationality evaluation system in mountainous small towns.By using fuzzy evaluation method based on the analytic hierarchy process(AHP),road network rationality evaluation system is analyzed in detail and values of the road network indexes are calculated with yaahp software.Finally,Nanhua County of Yunnan Province has been used as the case.Scores of the road network indexes of the central area and county area are calculated and corresponding suggestions have been put forward.