中文摘要：

影响真空管道交通建设成本与运营成本的因素很多,其中管道断面尺寸是最主要的影响因素。管道断面越小,显然建设成本越低。但小管道断面意味着阻塞比增加和空气阻力增大,对运营成本的影响并非显然。通过对真空管道中不同阻塞比、不同真空度时列车空气阻力的计算与比较,可知对于相同的空气阻力工况,减小断面所节省的抽真空能耗大于因提高真空度而增加的抽真空能耗。因此,当不考虑真空度提高所造成的维持真空成本的增加时,减小管道断面既是降低真空管道交通建设成本的有效途径,也是降低真空管道交通运营成本的有效途径。

英文摘要：

There are many factors in impacting the construction and operation costs of evacuated tube transportation（ETT）.Among them the tube section diameter is the most important one.The smaller the tube section,the less the construction cost of ETT.However,small tube section means high blockage rate as well as high air drag.It is thus needed to study how the reduction of tube section impact on the ETT operation cost.By calculating and comparing the air drag on train running in ETT tube at different blockage rates and different pressures,it is found that,for the same air drag situation,saved pumping energy due to reducing the tube section exceed the increased pumping energy due to increasing vacuum.Therefore,if not considering the cost increasing to maintain vacuum,it is efficient in reducing both the ETT construction and operation costs by using smaller tube section.