科研之友
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摘要
Traffic density can be accurately measured by counting the number of vehicles within 1km; however, it is often calculated between macroscopic traffic parameters using the fundamental equation because of difficulty of observing traffic density directly in the field. Measuring density in this way may be inaccurate and may bias the analysis because the relationship between these traffic parameters can vary across the study sites. The purpose of this study is to find a method for measuring traffic density from aerial photography that is easy and accurate, and for this purpose, we investigated whether the measuring length (i.e., the length of a section of roadway from which observations of traffic are simultaneously collected) can be shorter than 1km and yet retain the same measured traffic density. We divided an aerial photograph into several 20-m unit sections, counted the number of vehicles manually, and examined measured traffic density according to central limit theory. According to the results of this study, with the number of 20-m unit sections for observing traffic density at 15 (the measuring length is 300m), the measured traffic density was almost the same as the density of a representative section of 1km.
- 出版日期2015-6
