为探究青藏高原地区空气氧含量对大、小车运行速度差的影响，运用MetroCount 交通检测仪采集了109 国道部分路段的车辆运行速度数据，选取其中不同氧含量下的3 个平直路段、2 个平曲路段及2 个纵坡路段的数据作为研究对象，进行统计分析，并建立回归模型。分析得出：平直路段下，随着氧含量的降低，大、小车运行速度差逐渐增大；氧含量在50%~55%区间内时，速 度差增大趋势逐渐平缓，最终稳定在20km· h-1；同氧含量时，大、小车速度差在纵坡和平曲路段下较平直路段都会进一步增大，其中较低氧含量时在纵坡路段下速度差增加幅度较大，较高氧含量时平曲路段下速度差变化更为显著。结果表明：大、小车速度差在一定程度上与空气中的氧含量呈 负相关性。

In order to study the influence of oxygen content on driving speed difference in Tibet Plateau, some driving speed data of sections on National Road No.109 were collected using MetroCount devices. The data of 3 tangent sections, 2 horizontal curve sections and 2 longitudinal gradient sections under different oxygen contents were selected for statistical analysis. A regression model was established based on the result of this statistical analysis. It shows that the speed difference of truck and car increases as the oxygen content on tangent sections decreases; the increased value curve is flat when oxygen content ranges from 50% to 55%; the speed difference finally remains stably around 20km·h-1. In the same oxygen content, the speed difference on horizontal curve sections and longitudinal gradient sections would increase compared with that on tangent sections. The former is more significant under low oxygen content and the latter is more obvious under high oxygen content. Results show that the speed difference of truck and car partly has negative correlation with the oxygen content in the air.