Congresos de la Universitat Politècnica de València, CIT2016. Congreso de Ingeniería del Transporte

Por defecto: 
An algorithm for the estimation of road traffic space mean speeds from double loop detector data
Margarita Martínez-Díaz, Ignacio Pérez Pérez

Última modificación: 04-06-2016

Resumen


Most algorithms trying to analyze or forecast road traffic rely on many inputs, but in practice, calculations are usually limited by the available data and measurement equipment. Generally, some of these inputs are substituted by raw or even inappropriate estimations, which in some cases come into conflict with the fundamentals of traffic flow theory. This paper refers to one common example of these bad practices.

Many traffic management centres depend on the data provided by double loop detectors, which supply, among others, vehicle speeds. The common data treatment is to compute the arithmetic mean of these speeds over different aggregation periods (i.e. the time mean speeds). Time mean speed is not consistent with Edie’s generalized definitions of traffic variables, and therefore it is not the average speed which relates flow to density. This means that current practice begins with an error that can have negative effects in later studies and applications.

The algorithm introduced in this paper enables easily the estimation of space mean speeds from the data provided by the loops. It is based on two key hypotheses: stationarity of traffic and log-normal distribution of the individual speeds in each time interval of aggregation. It could also be used in case of transient traffic as a part of any data fusion methodology.

DOI: http://dx.doi.org/10.4995/CIT2016.2016.3208

 


Palabras clave


space mean speeds, time mean speeds, loop detectors

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