交通投资与经济发展的关系及其区域效应评价方法研究

交通投资与经济发展的内在关系一直没有公认的结论。大家普遍同意交通条件是经济发展的重要支撑要素之一。交通投资只有在生产条件充足的情况下，才会促进经济发展。但交通投资并不是越多越好，而是必须与生产投资保持适当比例。交通投资对交通条件改善的区域影响较为复杂，不同的范围有不同的影响。通达性是目前进行交通网络影响评价最为常用的手段。通达性指标有时间通达性、经济潜能和日通达性。不同的通达性指标从不同的角度对交通网络区域效应进行评价。本旨在对我国主要交通设施区域影响的评价研究起抛砖引玉的作用。

STUDIES ON THE RELATION BETWEEN TRANSPORT INVESTMENT AND ECONOMIC DEVELOPMENT AND REGIONAL IMPACTS OF TRANSPORT IMPROVEMENT

The link between transport investment and economic development is so complicate that there is no received conclusion of it. This study indicates that three sets of necessary conditions must be present to allow economic development to take place. The first condition is the presence of underlying positive economic externalities, such as agglomeration and labor market economics, the availability of a good quality labor force. The second conditions are investment factors which relate to the availability and scales of funds for the investment, and its location, the network effects, and the actual timing of the investment. The third constitutes are political factors, which are related to the broader policy environment within which transport decision must be taken. These three necessary conditions individually will have little or no impact on development. Even if they are combined on a pair-wise basis their effect will be limited. The relation between transport investment and other investments must be taken into account, because they are competitive each other. We use models to conclude that the transport investment must keep appropriate proportion with product investment to realize optimal economic development. If the equilibrium of them is broken, government must adjust investment to enhance the weak one. Accessibility is a common approach to measure the regional impact of a new transport infrastructure. Accessibility involves a combination of two elements: location on a surface relative to suitable destination, and the characteristics of the transport network or networks linking points on that surface. There is a wide variety of indicators to measure accessibility. We select three indicators that respond to different conceptualizations. The first one is weighted average travel times. The weighted average travel time between each node and all urban agglomerations is calculated taking as weight the mass of the centers. The second one is economic potential, which is a gravity-based measure model. According to this model, the level of opportunity between two nodes is positively related to the mass of the destination and inversely proportional to some power of the distance between both nodes. The indicator measures the economic potential of each place in each of the scenarios considered and the changes in potential caused by the new infrastructure. The third one is daily accessibility indicator, which consists of calculating the amount of population that can be reached from a node within a certain travel time limit. The time limit is usually established in 3 to 5 hours, so that it is possible to go and return within the day and carry out an activity at the visit location. The three indicators handle the distance (travel time) in a different way that the economic potential indicator has distance decay and others has not.