Average Velocity Of Vehicles Research Articles

Dynamic origin-to-destination routing of wirelessly connected, autonomous vehicles on a congested network

Up-to-date information wirelessly communicated among vehicles can be used to select the optimal route between a given origin and destination. To elucidate how to make use of such information, simulations are performed for autonomous vehicles traveling on a square lattice of roads. All the possible routes between the origin and the destination (without backtracking) are of the same length. Congestion is the only determinant of delay. At each intersection, right-of-way is given to the closest vehicle. There are no traffic lights. Trip times of a subject vehicle are recorded for various initial conditions using different routing algorithms. Surprisingly, the simplest algorithm, which is based on the total number of vehicles on a route, is as good as one based on computing travel times from the average velocity of vehicles on each road segment.

Comparison of real driving cycles and consumed braking power in suburban Slovakian driving

The paper compares the features of suburban real driving cycles performed with CORRSYS DATRON measurement equipment on routes in the region of Žilina, Slovakia. It observes differences in the maximum and average vehicle velocities and the amount of braking in relation to the elevation profile of each individual cycle. Consumed braking power was also calculated in the different cycles in order to review the potential electricity regeneration capabilities of hybrid electric vehicles, operating on the same routes. The change in braking energy depending on vehicle mass and presence of grade on the routes in the measured cycles was also assessed. The calculations and plotting were done by using Matlab software.

Survey of the Influence of the Width of Urban Branch Roads on the Meeting of Two-Way Vehicle Flows.

Branch roads, which are densely distributed in cities, allow for the flow of local traffic and provide connections between the city and outlying areas. Branch roads are typically narrow, and two-way traffic flows on branch roads are thus affected when vehicles traveling in opposite directions meet. This study investigates the changes in the velocities of vehicles when they meet on two-way branch roads. Various widths of branch roads were selected, and their influence on traffic flows was investigated via a video survey. The results show that, depending on the average vehicle velocity, branch roads require different widths to prevent a large decrease in velocity when vehicles meet. When the velocity on a branch road is not high (e.g., the average velocity without meeting is approximately 6 m/s), appropriately increasing the road width will notably increase the meeting velocity. However, when the velocity is high (e.g., the average velocity without meeting is greater than 10 m/s), there is a large decrease in velocity when meeting even if the road surface is wide (6.5 m). This study provides a basis for selecting the width of urban branch roads and the simulation of bidirectional traffic on such roads.

Local Optimization Strategies in Urban Vehicular Mobility.

The comprehension of vehicular traffic in urban environments is crucial to achieve a good management of the complex processes arising from people collective motion. Even allowing for the great complexity of human beings, human behavior turns out to be subject to strong constraints—physical, environmental, social, economic—that induce the emergence of common patterns. The observation and understanding of those patterns is key to setup effective strategies to optimize the quality of life in cities while not frustrating the natural need for mobility. In this paper we focus on vehicular mobility with the aim to reveal the underlying patterns and uncover the human strategies determining them. To this end we analyze a large dataset of GPS vehicles tracks collected in the Rome (Italy) district during a month. We demonstrate the existence of a local optimization of travel times that vehicle drivers perform while choosing their journey. This finding is mirrored by two additional important facts, i.e., the observation that the average vehicle velocity increases by increasing the travel length and the emergence of a universal scaling law for the distribution of travel times at fixed traveled length. A simple modeling scheme confirms this scenario opening the way to further predictions.

The Study of Traffic Rules Based on Cellular Automata Traffic Wave Model

The traffic control problem is a hot issue in recent years. We investigate the effectiveness of three traffic rules in assuring safety and improve traffic flow. We utilize a cellular automata method of traffic flow to investigate and simulate the vehicle performance and use a linear weighting approach to weigh safety and traffic flow comprehensively. We establish overtaking models of a two-lane freeway on the basis of the stochastic traffic cellular automaton (STCA) model. Using the cellular automata method, we simulate the relationships between the traffic flows, the average vehicle velocity, and the vehicle density. We propose two new traffic rules, which in the premise of ensuring safety and improve traffic flow.

LSGO: Link State aware Geographic Opportunistic routing protocol for VANETs

Abstract Robust and efficient data delivery in vehicular ad hoc networks (VANETs) with high mobility is a challenging issue due to dynamic topology changes and unstable wireless links. The opportunistic routing protocols can improve the reliability of routing by making full use of the broadcast characteristics and assist in data transmission through additional backup links. In this paper, we propose a Link State aware Geographic Opportunistic routing protocol (LSGO) which exploits a combination of geographic location and the link state information as the routing metric. The LSGO aims to improve the reliability of data transmission in a highly dynamic environment, which selects the forwarders and prioritizes them based on the vehicle’s geographic location and the link’s quality. We compare the performance of LSGO with GpsrJ + which removes the unnecessary stop at a junction and greedy traffic aware routing protocol (GyTAR) using network simulator ns-2. The simulation results show that it opens more nodes to participate in the opportunistic data forwarding and increases a connection’s throughput while using no more network capacity than traditional routing. In the simulation, compared with other two protocols, when the number of vehicles and the average vehicle velocity increase, LSGO’s packet dropping rate is reduced and the network throughput is improved.

Classification of Mobility of Cellular Phone Using Linear Classification and k-Clustering

Road traffic data is a fundamental element of intelligent traffic system. However, due to the high investment of the road sensor, the availability of the traffic data is so limited that it can’t satisfy the requirement of current situation. Using cellular phone information as road traffic data becomes an attractive alternative because of its low cost, widespread and high cover rate. Until now, there are several algorithms to process the cellular phone information and most of them present promising conclusion. However, in order to get the satisfying conclusion, nearly all of these methods depend on a high amount of sample, in which way will detract the real-time performance of the traffic regulation and control. This is we don’t want to see. In this paper, we proposed a process to collect the information of cellular phone based on the simulation of working mode of the real base station, i.e., putting an appropriate instrument on the side of the road to detect the cellular phone passing by. Using the data we got, then we proposed a method to classify the mobility of the cellular phone, which is the critical problem of the analysis of the cellular phone information. Two key attributes are the average vehicle velocity and the variance of the vehicle velocity.

Optimal distribution of traffic flows in emergency cases

The aim of this work is to present a technique for the optimisation of emergency vehicles travel times on assigned paths when critical situations, such as car accidents, occur. Using a fluid-dynamic model for the description of car density evolution, the attention is focused on a decentralised approach reducing to simple junctions with two incoming roads and two outgoing ones (junctions of 2 × 2 type). We assume the redirection of cars at junctions is possible and choose a cost functional that describes the asymptotic average velocity of emergency vehicles. Fixing an incoming road and an outgoing road for the emergency vehicle, we determine the local distribution coefficients that maximise such functional at a single junction. Then we use the local optimal coefficients at each node of the network. The overall traffic evolution is studied via simulations, both for simple junctions or cascade networks, evaluating global performances when optimal parameters on the network are used.

Optimal Flows On Road Networks In Emergency Cases

In this paper, we present a technique to redistribute car flows, described by a fluid dynamic model, on a portion of the Caltanissetta city, in Italy, when critical situations, such as car accidents, occur. Using a decentralized approach, a cost functional, that describes the asymptotic average velocity of emergency vehicles, is maximized with respect to distribution coefficients at simple junctions with two incoming roads and two outgoing ones. Then, in order to manage critical situations in high traffic conditions, local optimal coefficients at each node of the network are used. The overall traffic evolution is studied via simulations, that confirm the goodness of the optimization results. It is also proved that optimal coefficients allow a fast transit of emergency vehicles on assigned routes on the network.

Mitigation of congestion at a traffic bottleneck with diversion and lane restrictions

Mitigation of congestion on a two-lane highway with an off-ramp and an on-ramp is simulated with three-phase traffic theory. Advanced travel information–the average velocity of vehicles near the bottleneck at an on-ramp–is used to divert vehicles at an upstream off-ramp. If enough vehicles divert, previously expanding synchronous flow congestion can be stalled and isolated to the region between the ramps. The introduction of lane restrictions (forbidding lane changing on the portion of highway between the ramps) in addition to diversion substantially reduces and essentially eliminates the congestion, restoring flow to nearly free-flow conditions.

The effect of Reynolds number on the propulsive efficiency of a biomorphic pulsed-jet underwater vehicle

The effect of Reynolds number on the propulsive efficiency of pulsed-jet propulsion was studied experimentally on a self-propelled, pulsed-jet underwater vehicle, dubbed Robosquid due to the similarity of its propulsion system with squid. Robosquid was tested for jet slug length-to-diameter ratios (L/D) in the range 2–6 and dimensionless frequency (StL) in the range 0.2–0.6 in a glycerin–water mixture. Digital particle image velocimetry was used for measuring the impulse and energy of jet pulses from the velocity and vorticity fields of the jet flow to calculate the pulsed-jet propulsive efficiency, and compare it with an equivalent steady jet system. Robosquid's Reynolds number (Re) based on average vehicle velocity and vehicle diameter ranged between 37 and 60. The current results for propulsive efficiency were compared to the previously published results in water where Re ranged between 1300 and 2700. The results showed that the average propulsive efficiency decreased by 26% as the average Re decreased from 2000 to 50 while the ratio of pulsed-jet to steady jet efficiency (ηP/ηP, ss) increased up to 0.15 (26%) as the Re decreased over the same range and for similar pulsing conditions. The improved ηP/ηP, ss at lower Re suggests that pulsed-jet propulsion can be used as an efficient propulsion system for millimeter-scale propulsion applications. The Re = 37–60 conditions in the present investigation, showed a reduced dependence of ηP and ηP/ηP, sson L/D compared to higher Re results. This may be due to the lack of clearly observed vortex ring pinch-off as L/D increased for this Re regime.

Propulsive efficiency of a biomorphic pulsed-jet underwater vehicle

The effect of the velocity program and duty cycle (StL) on the propulsive efficiency of pulsed-jet propulsion was studied experimentally on a self-propelled, pulsed-jet underwater vehicle, dubbed Robosquid due to the similarity of essential elements of its propulsion system with squid jet propulsion. Robosquid was tested for jet slug length-to-diameter ratios (L/D) in the range 2–6 and StL in the range 0.2–0.6 with jet velocity programs commanded to be triangular or trapezoidal. Digital particle image velocimetry was used for measuring the impulse and energy of jet pulses to calculate the pulsed-jet propulsive efficiency and compare it with an equivalent steady jet system. Robosquid's Reynolds number (Re) based on average vehicle velocity and vehicle diameter ranged between 1300 and 2700 for the conditions tested. The results indicated better propulsive efficiency of the trapezoidal velocity program (up to 20% higher) compared to the triangular velocity program. Also, an increase in the ratio of the pulsed-jet propulsive efficiency to the equivalent steady jet propulsive efficiency (ηP/ηP, ss) was observed as StL increased and L/D decreased. For cases of short L/D and high StL, ηP/ηP, ss was found to be as high as 1.2, indicating better performance of pulsed jets. This result demonstrates a case where propulsion using essential elements of a biological locomotion system can outperform the traditional mechanical system equivalent in terms of efficiency. It was also found that changes in StL had a proportionately larger effect on propulsive efficiency compared to changes in L/D. A simple model is presented to explain the results in terms of the contribution of over-pressure at the nozzle exit plane associated with the formation of vortex rings with each jet pulse.

Effects of Reduced Visibility from Fog on Car-Following Performance

A study examined the effects of reduced visibility of scene information because of fog on car-following performance. Drivers were presented with a straight roadway scene in a driving simulator and were asked to maintain a predetermined driving distance in response to speed variations of a lead vehicle. Lead vehicle speed varied according to a sum of three prime sine wave frequencies. Five simulated fog density conditions and three average lead vehicle velocities were examined. Car-following performance was assessed using distance headway, variance of distance headway, root-mean-square (RMS) velocity error, control gain, phase angle, and squared coherence. Distance headway decreased only at the highest fog density condition examined. RMS velocity error increased with an increase in fog density. These results indicate that drivers had greater difficulty responding to changes in lead vehicle speed than to changes in headway. Results for squared coherence indicated that the effects of fog were greatest for the highest rate of change in lead vehicle speed (i.e., highest frequency examined). The importance of visual factors for optimal car-following performance is discussed.

THE EFFECT OF MIXED VEHICLES ON TRAFFIC FLOW IN TWO LANE CELLULAR AUTOMATA MODEL

In real traffic, the traffic system is usually composed of different types of vehicles, which have different parameters. How these parameters, especially the lengths of the vehicles, influence the traffic behaviors and transportation capability has seldom been investigated. In this paper, we study the mixed traffic system using the cellular automata traffic flow model. The simulation results show that when the road occupancy rate is large, increasing the fraction of long vehicles can apparently, improve the transportation capability. The influence of slow vehicles fraction on the average velocity of vehicles has been discussed, and it is found that the influences are very different when the difference of vehicle length is considered or not.

Analyses of shock waves and jams in traffic flow

In this paper, we study the certain qualitative properties of a new anisotropic continuum traffic flow model in which the dimensionless parameter or anisotropic factor controls the non-isotropic character and diffusive influence. We discussed the travelling wave solution for our model and find out the condition for the shock wave. Shock and rarefaction waves are obtained from the new model and are consistent with the diverse nonlinear dynamical phenomena observed in a real traffic flow. However, our model for large values of anisotropic parameter removes the discontinuity as pointed out by Berg et al (2000 Phys. Rev. E 61 1056). The nonlinear theory of the cluster effect in a traffic flow i.e., the effect of appearance of a region of high density and low average velocity of vehicles in an initially homogeneous flow, is also discussed. It is shown that an appearance of a localized perturbation of finite amplitude in the stable homogeneous flow can lead to a self-formation of a local cluster of vehicles. It is also been observed that the cluster effect from our model shows a good agreement with the results of Kerner and Konhauser (1994 Phys. Rev. E 50 54) and Jiang et al (2002 Trans. Res. B 36 405).

Simulator Sickness Results Obtainted During a Novice Driver Training Study

Simulator sickness results have been obtained in a novice driver training experiment with approximately 500 young drivers who have yet to receive their license to drive. Different participant groups were trained on three different PC based driving simulator configurations: 1) a single-monitor desktop unit, 2) a wide field-of-view three-monitor desktop unit, and 3) a wide field-of-view projected image with an instrumented cab. Simulation sickness ratings scores were obtained using a four-point rating scale provided to participants after each training trial. Between-subject effects were broken down according to the three simulator configuration types and gender across six training trial runs. Analysis for average vehicle velocity was also reported as it may have been related to simulator sickness. While the incidence of simulator sickness was quite small, participants using the single-monitor configuration unexpectedly reported the highest incidence of symptoms. Some gender differences were also found according to training trials. Possible explanations for the results are provided along with experience with high school driver education programs.

ライフサイクルアセスメント （ＩＩ） ガソリン自動車と電気自動車のライフサイクルアセスメント

Life cycle assessment (LCA) is expected to be a useful measure for us to evaluate environmental impacts associated with products or processes, so that we could improve our production systems for sustainable development. For this purpose, we have developed a novel mathematical tool called Process-relational Model. In the model, we have improved the principle of input-output analysis so as to include joint production. This improvement has enabled us to overcome difficulties of LCA in retracing complicated repercussions among production systems and in allocating environmental emissions among multiple products.Then life cycle CO2 emissions of electric and gasoline vehicles have been estimated with this model. We have shown that production and driving of electric vehicles cause less CO2 emissions than those of gasoline vehicles. Our analysis has also indicated that the difference detween electric and gasoline vehicles dramatically changes depending on traffic situation. Namely the difference becomes larger, as average velocity of vehicles becomes lower. Concerning electric vehicles, we have compared CO2 emissions caused by production with those caused by driving. The share of production has increased, as average velocity becomes higher.In conclusion, we have clarified directions of research and development of electric and gasoline vehicles for sustainable energy system.

Structure and parameters of clusters in traffic flow.

The nonlinear theory of the cluster effect in a traffic flow [B. S. Kerner and P. Konh\"auser, Phys. Rev. E 48, 2335 (1993)], i.e., the effect of the appearance of a region of high density and low average velocity of vehicles in an initially homogeneous flow, is presented. The structures of a stationary moving cluster are derived. It is found that the density, the average velocities of vehicles inside and outside the cluster, and also the velocity of the cluster are the characteristic parameters of the traffic flow. The dependencies of the cluster structure and parameters on the density of vehicles in the initially homogeneous flow and on the length of the road are investigated. It is found that the cluster can appear within regions of density of vehicles which correspond to a stable homogeneous flow. It is shown that an appearance of a localized perturbation, having a finite amplitude, in the stable homogeneous flow can lead to a self-formation of a local cluster of vehicles which is surrounded by the homogeneous traffic flow. The parameters of the local cluster do not depend on the amplitude of this perturbation but only on the parameters of the flow.

A simple method for predicting kerbside [formula omitted] level from a free multi-type vehicular flow

The aim of this paper is to offer a simple and practical method, and prediction tables, for forecasting the kerbside L 10 levels generated from a free traffic flow consisting of multi-type vehicles. This method is suitable for cases where the traffic volume on each lane is small, say, not more than 600 veh h −1 , and the average velocity of vehicles is slow.