Transformation between Uninterrupted and Interrupted Speeds for Urban Road Applications

Abstract

Unlike freeway, urban traffic stream is generally interrupted by signal, and thus observed traffic data may differ from the true (uninterrupted) flow characteristic. This paper deals with the transformation between interrupted and uninterrupted speed on urban road with signalized intersection. Conventional shock wave model and two modified versions of shock wave boundary that address for the unrealistic characteristics of the conventional shock wave are developed. A method of integrating probes and detector data for speed transformation is also discussed. The proposed methods are tested with a virtual isolated signalized intersection by varying the approach demand. The numerical results suggest that all models can significantly reduce the difference between the actual and the estimated uninterrupted (or interrupted) speed compared to the case of no conversion. The applications of the proposed methods including the development of flow-speed model and link travel time estimation are also given. Limitations of the model are explained, and the areas of potential improvement are suggested.

Understanding traffic capacity of urban networks

“…The first step values are irrelevant as they are completely re-calibrated in the second step. First, to reduce the noise at the detector level, we rescale occupancy in such a way that q / o (approximation of speed) for each detector in free flow conditions corresponds to the average speed expected at that location 42 . This does not change the information provided by the detector, but reduces the scatter in the aggregation as rescaled occupancy measurements now have a similar physical interpretation.…”

Comparative Analysis of Deterministic Fundamental Diagrams Representative of Continuous and Interrupted Traffic Flow on Selected Regional Road in Croatia

“…In their pursuit of finding the optimal deterministic and stochastic functional forms for the "speed-density", "flow-density" and "flow-speed" models, the majority of researchers have predominantly focused on studying vehicle interactions within uninterrupted traffic flow conditions, which has been regarded as the basic traffic flow condition representative of establishing the fundamental relations between the main traffic flow parameters. On the other hand, only a limited number of researchers have studied specific functional relationships between the macroscopic and microscopic traffic flow parameters under interrupted traffic flow conditions [37][38][39][40][41][42][43][44] and discussed the comparative differences between the values of traffic flow parameters measured in uninterrupted and interrupted traffic flow conditions [45][46][47][48]. In a 1996 study, Akcelik provided a comparative overview of the mathematical relations between speed, density and travel time, which can be used to describe the characteristics of traffic flow in uninterrupted and interrupted traffic stream conditions [45].…”

“…In a 1996 study, Akcelik provided a comparative overview of the mathematical relations between speed, density and travel time, which can be used to describe the characteristics of traffic flow in uninterrupted and interrupted traffic stream conditions [45]. In 2005, Pueboobpaphan, Nakatsuji, Suzuki and Kawamura developed three distinct shock wave models, which can be used to convert vehicle speeds measured within uninterrupted traffic stream conditions on a road segment located prior to a signalized intersection into vehicle speeds present in the interrupted traffic stream conditions formed in the immediate vicinity of the signalized intersection [46]. In the same year, Pueboobpaphan et al attempted to identify the relationship between vehicle speeds in uninterrupted and interrupted traffic stream conditions using the method of characteristics [47].…”

“…In 2005, Pueboobpaphan, Nakatsuji, Suzuki and Kawamura developed three distinct shock wave models, which can be used to convert vehicle speeds measured within uninterrupted traffic stream conditions on a road segment located prior to a signalized intersection into vehicle speeds present in the interrupted traffic stream conditions formed in the immediate vicinity of the signalized intersection [46]. In the same year, Pueboobpaphan et al attempted to identify the relationship between vehicle speeds in uninterrupted and interrupted traffic stream conditions using the method of characteristics [47]. In a study conducted in 2021, Barka and Polis performed a calibration of the most commonly used volume-delay models, including BPR, Conical, Akcelik and modified Davison model, for continuous and interrupted traffic stream conditions in different road categories in the urban area of Thessaloniki in Greece [48].…”

Modeling of Travel Time Variations on Urban Links in London

“…Accurate predictions of travel times are important for transportation planning, as well as for operations of traffic management centers theory (24), which was later enhanced by Pueboobpaphan et al by combining probe vehicle data with detector data (25). Ruiz Juri et al presented an approach of combining statistical forecasting techniques with traffic simulation for online short-term prediction of point-to-point freeway travel time (26).…”