Abstract: Because realtime traffic information is not available from current probe vehicle system, archived probe data become extremely important in studying timeofday variability of traffic condition. Timeofday variability of mean travel speed of a particular link is analyzed based on archived probe data from a field experiment conducted by the Nagoya PDRGS research association, Japan. The analysis shows that the mean travel time cannot reflect the variability of road traffic condition. For measuring variability, the mean speed and the amount of probe data should be used; in peak hours, mean speed reflects the variability of congestion and in offpeak hours, the amount of probe data can reflect the variability of traffic condition.

Key words: intelligent transportation systems (ITS), traffic condition estimation, probe vehicle/floating car, archived probe data, urban road

摘要： 现有探测车系统的探测车数量不足，尚无法满足实时采集交通状况的需求.因此，现阶段探测车历史数据是了解城市道路的交通状况变化（Time of day variability）的重要依据.基于日本名古屋探测车实证试验获得的探测车历史数据，研究了某一干线路段的平均速度的变化特性（Timeof day variability），并分析了平均速度的变动是否能够正确地反映路段交通状况的变化特性.结果表明，获取城市道路的路段交通状态不能仅依靠平均路段旅行时间、平均速度等旅行时间指标，还需要探测车数据量等流量指标：在高峰时段，应以平均速度等旅行时间指标作为拥挤程度变化趋势的依据，而在非高峰时段，应以探测车数据量等流量指标作为估计交通状况变化趋势的依据.

关键词: 智能交通系统, 交通状态估计, 探测车/浮动车, 历史数据, 城市道路