Search results for "traffic flow"
showing 10 items of 48 documents
Probabilistic description of traffic breakdowns
2001
We analyze the characteristic features of traffic breakdown. To describe this phenomenon we apply to the probabilistic model regarding the jam emergence as the formation of a large car cluster on highway. In these terms the breakdown occurs through the formation of a certain critical nucleus in the metastable vehicle flow, which enables us to confine ourselves to one cluster model. We assume that, first, the growth of the car cluster is governed by attachment of cars to the cluster whose rate is mainly determined by the mean headway distance between the car in the vehicle flow and, may be, also by the headway distance in the cluster. Second, the cluster dissolution is determined by the car …
Metastability of Traffic Flow in Zero-Range Model
2007
The development of traffic jams in vehicular flow is an everyday example of the occurence of phase separation in low-dimensional driven systems, a topic which has attracted much recent interest [1–4]. In [5] the existence of phase separation is related to the size-dependence of domain currents and a quantitative criterion is obtained by considering the zero-range process (ZRP) as a generic model for domain dynamics. We use zero-range picture to study the phase separation in traffic flow in the spirit of the probabilistic (master equation) description of transportation [6]. Significantly, we find [7] that prior to condensation studied in previous works [8, 9] the system can exist in a homoge…
Stochastic description of traffic breakdown
2003
We present a comparison of nucleation in an isothermal-isochoric container with traffic congestion on a one-lane freeway. The analysis is based, in both cases, on the probabilistic description by stochastic master equations. Further we analyze the characteristic features of traffic breakdowns. To describe this phenomenon we apply the stochastic model regarding the jam emergence to the formation of a large car cluster on the highway.
Dynamic routing-and-inventory problems: a review
1998
The paper presents a review of the available literature on a class of problems denoted as dynamic routing-and-inventory (DRAI) problems. They are characterized by the simultaneous relevance of routing and of inventory issues in a dynamic environment, within the framework of distribution logistics. A classification scheme is first proposed for these problems. Then the results obtained in this area are summarized. Finally, the papers available in the literature are clustered and discussed according to the proposed scheme.
A behavioural model to evaluate the delay on urban traffic flows and analysis of environmental implications
2014
This paper deals the problem of a road's capacity in presence of perturbations in the vehicular flow. In particular, among the different causes of delay, is here the presence of vehicles parked along the road in relation at their parking activity. Preliminarily is evaluated the delay, caused by each vehicle that leaves its parking position and enters in the traffic flow or by that who slows down the flow to enter in the parking, by introducing these effects in the equations of flow, it is possible to evaluate the modifications that the same curves of down flow suffer. Consequently, it is also possible to evaluate the increase of pollutant emissions.
Environmental Implications of Traffic Flow Delays: a Model for Urban Streets
2013
In this paper the problem of road's capacity is dealt in presence of perturbations of the vehicular flow. In particular, among the different disturbing causes, it is here considered the presence of vehicles parked along the road in relation to their parking activity. Having already established the delay, caused by those vehicles leaving their stationary positions and entering the traffic flow or by those who slow down the flow to park, it is possible to evaluate the changes in time running values. Related to these times delay, the extra pollutant emissions by a given urban running fleet is also evaluated, by utilizing emission factors depending on age, type, volume capacity and engine of th…
Urban Traffic Analysis through an UAV
2014
Abstract In order to realize a precise and accurate traffic study, a method to evaluate the real traffic flow conditions in urban areas based on videos acquired by an UAV, Unmanned Aerial Vehicle, is proposed. In this way it does not require additional equipment to earth and, not being invasive, does not influence the driver behavior. This paper presents the results obtained in terms of vehicular traffic flow along a way in the city of Palermo. The results have been compared to experiments using macroscopic simulation models and the eventually differences have been discussed.
TWO-LANE TRAFFIC WITH PLACES OF OBSTRUCTION TO TRAFFIC
2004
As the Nagel–Schreckenberg model (NaSch model) became known as a realistic approach to describe traffic flow on single-lane streets, this model was extended to two-lane traffic by several groups. On the base of our two-lane model, we will now investigate the impact of a place of obstruction, e.g., because of road works, on partial fractions, densities and mean velocities.
TRAFFIC FLOW HYPOTHETICAL MODELLING FOR AIR QUALITY IMPROVEMENT AND PLANNING PURPOSES
2019
The main emphasis of this research was to describe air pollution level and dispersion in a typical street canyon (Valdemara Street in Riga (Latvia) city centre), afterward to postulate potential development scenarios and perform modelling in order to understand the influence on air pollution level. For this purpose special mathematical model was used - Operational Street Pollution Model (OSPM), which was developed by the National Environmental Research Institute in Denmark. Following development scenarios were tested: (1) realistic environmentally friendly - decrease of traffic flow by 50 %, as according to street interviews about 36 - 50 % of drivers are ready to change driving habits from…
Environmental Implications of Traffic Flow Delays: A Model for Urban Streets
2012
In this paper the problem of road's capacity is dealt in presence of perturbations of the vehicular flow. In particular, among the different disturbing causes, it is here considered the presence of vehicles parked along the road in relation to their parking activity. Having already established the delay, caused by those vehicles leaving their stationary positions and entering the traffic flow or by those who slow down the flow to park, it is possible to evaluate the changes in time running values. Related to these times delay, the extra pollutant emissions by a given urban running fleet is also evaluated, by utilizing emission factors depending on age, type, volume capacity and engine of th…