|標題：Characteristics of speed dispersion and its relationship to fundamental traffic flow parameters|
|作品名稱||Characteristics of speed dispersion and its relationship to fundamental traffic flow parameters|
|著者||Chih-Lin Chung; Will W. Recker|
|著錄名稱、卷期、頁數||Transportation Planning and Technology 37(7), pp.581-597|
|摘要||Speed dispersion is essential for transportation research but inaccessible to certain sensors that simply record density, mean speed, and/or flow. An alternative is to relate speed dispersion with these available parameters. This paper is compiled from nearly a quarter million observations on an urban freeway and a resulting data-set with two speed dispersion measures and the three fundamental parameters. Data are examined individually by lane and aggregately by direction. The first dispersion measure, coefficient of variation of speed, is found to be exponential with density, negative exponential with mean speed, and two-phase linear to flow. These empirical relationships
are proven to be general for a variety of coefficient ranges under the above function forms. The second measure, standard deviation of speed, does not present any simple relationships to the fundamental parameters, and its maximum occurs at around a half to two-thirds of the free flow speed. Speed dispersion may be significantly different by lane.
|關鍵字||speed dispersion;coefficient of variation of speed;standard deviation of speed;macroscopic traffic flow model|