基于优化模型的中国民用运输机场人口覆盖评价

随着中国机场建设速度加快,机场布局评价及优化已成为交通地理学重要的研究议题。针对县级需求点,对中国2005年和2010年机场布局进行基于优化覆盖模型的模拟,进而从覆盖率、重叠率和冗余度三个指标对机场布局进行全国和分区的评价。结果表明:"十一五"期间,中国机场布局在人口覆盖率方面有明显提升,但与最优覆盖率相比还存在一定的优化空间,在中部布局机场能更大地提高机场人口覆盖率。人口重叠率虽有所上升,但与最优重叠率的差异缩小了,故整体重叠率实际得到了较好的优化,分区有一定差异:东部实际重叠率高于最优重叠率,而中部还需提高约10%才能达到最优重叠率。有效服务半径这一地理概念在机场规划中的引入对重叠率改善起到了一定作用,但也是造成2010年机场冗余度上升的原因之一。

Population coverage evaluation of civil airports in China based on optimization models

In recent years, with the rapid growth of China's airports, the overlap of airports' market areas has gained increasing attention. The efficiency evaluation of airports' spatial distribution and spatial optimization of the airport layout have become a key topic in transportation geography. Based on the county-level population data in 2010, this study develops three indexes, namely population coverage ratio, population overlap ratio and redundancy ratio, and uses them to evaluate the efficiency of population coverage of civil airports during the 11th Five-year Plan (from 2005 to 2010) by comparing the three indexes of actual airports layout with the indexes from optimal models. Covering models, such as Location Set Covering Problem model and Maximal Covering Location Problem model, are used to identify the optimal airport locations and calculate the optimal indexes. The results indicate that the overall coverage ratio of China's airport system was greatly improved from 2005 to 2010, but still can be further optimized with an increase of about 27% both in 2005 and 2010. Therefore, more airports should be built in the central region of China to realize the optimization. The overlap ratio in 2010 is raised but closer to the optimal overlap ratio, which means the overlap of airports' areas was also improved from 2005 to 2010. This result also indicates that the lower population overlap ratio does not necessarily mean a better layout of the Chinese airport system, because to achieve maximum coverage is generally at the cost of a certain increase in the overlap ratio. There is a significant spatial variation in the overlap ratio. The overlap ratio of airports in the eastern region of China is higher than the optimal overlap ratio, but the overlap ratio in the central region of China is about 10% lower than the optimal overlap ratio. However, the airport redundancy increased from 2005 to 2010. One of the possible reasons is that the use of threshold distance in the airport planning improves the overlap ratio but also increases the redundancy ratio.