中文摘要：

以出租车作为浮动车数据采集探测车，针对探测车在路网上行驶的不确定性，提出浮动车数据路网覆盖能力的概念，研究覆盖能力与探测车样本量之间的关系。以覆盖强度和覆盖率为指标，采用简单随机抽样方法，研究了在10种样本条件下浮动车数据路网覆盖能力的变化情况，并进行回归分析。结果表明：在不同样本容量下，浮动车数据对各等级路网的覆盖强度和覆盖率均具有相似的时变特征；各等级路网的平均覆盖强度随样本容量线性增长，增长率随道路等级下降而迅速减小，高等级道路具有更高的覆盖强度：各等级路网的覆盖率随样本容量增大呈非线性增长，高等级道路能够更快达到稳定值：用浮动车数据判别高等级道路的交通状态，可适当降低样本容量。

英文摘要：

Taxies were selected as probe cars to collect Floating Car Data （FCD） which can be used to evaluate traffic conditions in road network. In order to study the uncertainty of probe cars when traveling in urban road network, the definition of Detecting Capability （DC） was put forward. The relationship between DC of FCD and probe car sample size was investigated, which can help find reasonable sample size. Two indexes named Detecting Intensity （DI） and Detecting Rate （DR） were designed to analyze the change of DC under 10 samples with different sample sizes by simple random sampling and regression. The result shows that （1） there are similar time-variable characteristics of DI and DR under different sample sizes; （2） average DI in the network increases linearly with the growth of sample size and the growth rate of DI in arterial roads is much higher than that in access roads; （3） DR in road network increases non-linearly with the growth of sample size and DR of arterial roads can reach steady-state value more rapidly than that of access roads when sample size increases; （4） the sample size of probe cars can be reduced when FCD are used to evaluate traffic conditions in arterial roads.