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A novel approach of structuring mission-critical systems with an emphasis on intrusion tolerance is described. Key components in the proposed system include traffic regulation, application request processing, state protection, integrity checking, and process/node health monitoring. In particular, the separation of execution and state management enables the use of a single process to manage application requests, thereby reducing run-time overhead and enables highly concurrent executions. Furthermore, intrusion attacks are mitigated by two means: (1) append-only state logging so that a compromised execution node cannot corrupt state updates from other nodes; and (2) acceptance testing as a way to verify the integrity of the execution of application requests. When an attack is detected, the malformed requests that materialized the attack are quarantined, and such requests (current and future ones) are rejected. [ABSTRACT FROM AUTHOR]

Cooperative vehicular ad-hoc networks are currently under development for improving traffic safety and efficiency. The strict requirements of traffic safety applications demand robust communication protocols that are able to efficiently operate under diverse and challenging operating conditions. In this context, this work proposes the joint study and evaluation of cooperative applications with potential dependencies, and evaluates a context-aware communications mechanism that exploits traffic context information to maximize the applications' effectiveness. The benefits of the proposed approach are illustrated with the intersection collision warning and emergency electronic brake lights applications. [ABSTRACT FROM AUTHOR]

Abstract: Combining with the basic idea of object-oriented modeling and modules modeling, according to the hierarchical relationships, the entities in the road network are abstracted as layer independent hierarchical model. A static and dynamic combination of generalized urban road network model is established. Road and road relationship sub-model of generalized road network model and the data structures information are analyzed. Moreover, real-time traffic information is taken into account, which lays the foundation for the study of dynamic path planning. [Copyright &y& Elsevier]

The Traffic Research Unit of the Vermont Agency of Transportation conducted more than 1,000 trip generation counts at various land uses, especially retail and service locations, in order to either verify the validity of or confirm the need for alternatives to the ITE trip generation rates used in traffic impact studies conducted throughout the state. The result of this research was publication of the Vermont Trip Generation Manual [ABSTRACT FROM AUTHOR]

Autonomous vehicles promise numerous improvements to vehicular traffic: an increase in both highway capacity and traffic flow because of faster response times, less fuel consumption and pollution thanks to more foresighted driving, and hopefully fewer accidents thanks to collision avoidance systems. In addition, drivers can save time for more useful activities. In order for these vehicles to safely operate in everyday traffic or in harsh off-road environments, a multitude of problems in perception, navigation, and control have to be solved. This paper gives an overview of the most current trends in autonomous vehicles, highlighting the concepts common to most successful systems as well as their differences. It concludes with an outlook into the promising future of autonomous vehicles. [ABSTRACT FROM PUBLISHER]

End-to-end traffic delay control within actual communication networks represents a very important goal for an administrator, due to the direct influence on service quality of service level, which is delivered to users. The difficulty of a maximal end-to-end delay prediction is related especially to the random traffic behaviour within waiting queues belonging to network nodes. The aim of this paper is to present a delay control proposal for the data traffic within a queue wherein is activated a weighted random early detection (WRED) congestion avoidance mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Real-time information can enable travelers to adapt to changing traffic conditions and make better routing decisions in uncertain networks. In this paper, a generic description of real-time online information is provided based on three schemes using partial online information and one scheme with no online information. A theoretical analysis shows that more error-free information is always better than (or at least as good as) less information for optimal adaptive routing in flow-independent networks. A heuristic algorithm is designed for the optimal adaptive routing problem for all the four information schemes, based on a set of necessary conditions for optimality. The effectiveness of the heuristic algorithm is shown to be satisfactory over the tested random networks. This study is of interest for traveler information system evaluation and design. [Copyright &y& Elsevier]

Estimation of intersection turning movements is one of the key inputs required for a variety of transportation analysis, including intersection geometric design, signal timing design, traffic impact assessment, and transportation planning. Conventional approaches that use manual techniques for estimation of turning movements are insensitive to congestion. The drawbacks of the manual techniques can be amended by integrating a network traffic model with a computation procedure capable of estimating turning movements from a set of link traffic counts and intersection turning movement counts. This study proposes using the path flow estimator, originally used to estimate path flows (hence origin-destination flows), to derive not only complete link flows, but also turning movements for the whole road network given some counts at selected roads and intersections. Two case studies using actual traffic counts are used to demonstrate the proposed intersection turning movement estimation procedure. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article discusses a study which evaluated traffic signal warrants to determine the shortcomings based on control delay. The study focused on 8-hour, 4-hour and peak-hour warrants from the "Manual on Uniform Traffic Control Devices (MUTCD)." An analysis of different scenarios were performed to develop the indifferent delay curves for an isolated intersection. The study found that the 8-hour volume warrant leniently satisfies the warrant for some volume combinations.

Microscopic traffic simulation models have advanced significantly in recent years and are now used extensively around the world for detailed traffic modelling where dynamic operations have to be represented. Whilst extremely powerful, these models can have substantial calibration requirements. This paper illustrates a new method of calibration of bus performance parameters as part of the ‘Gipps’ car-following model used within the microscopic simulation package Aimsun. This research looks at the impact of bus signal priority strategies on bus and traffic emissions. Calibration was undertaken using second-by-second bus performance data recorded automatically within the new iBus system in London. Results illustrate significant differences between some measured and default parameters, which in turn lead to some inaccuracies in emissions predictions for buses. Calibration is therefore essential and can benefit from the ever-increasing sources of automatic data emerging from new Intelligent Transport Systems applications. [ABSTRACT FROM PUBLISHER]

We study the traffic states and fundamental diagram of vehicular traffic controlled by a series of traffic lights using a deterministic cellular automaton (CA) model. The CA model is not described by a set of rules but is given by a difference equation. The vehicular traffic varies highly with both signal's characteristics and vehicular density. The dependence of fundamental diagram on the signal's characteristics is derived. At a low value of cycle time, the fundamental diagram displays the typical trapezoid, while it shows a triangle at a high value of cycle time. The dynamic transitions among distinct traffic states depend greatly on the signal's characteristics. The dependence of the transition points on the cycle time split and offset time is found. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyzes a model of early morning traffic congestion, that is a special case of the model considered in . A fixed number of identical vehicles travel along a single-lane road of constant width from a common origin to a common destination, with LWR flow congestion and Greenshields’ Relation. Vehicles have a common work start time, late arrivals are not permitted, and trip cost is linear in travel time and time early. The paper explores traffic dynamics for the social optimum, in which total trip cost is minimized, and for the user optimum, in which no vehicle’s trip cost can be reduced by altering its departure time. Closed-form solutions for the social optimum and quasi-analytic solutions for the user optimum are presented, along with numerical examples, and it is shown that this model includes the bottleneck model (with no late arrivals) as a limit case where the length of the road shrinks to zero. [Copyright &y& Elsevier]

The Istanbul Strait is one of the most congested waterways in the world and is difficult to navigate due to its ‘S-shaped’ geographic structure (Akten, 2004). Much of the local marine traffic affects navigation safety. Results of Yurtoren and Inoue (2004)'s study, which investigated navigational risks in the Istanbul Strait in terms of manoeuvring difficulties and accident statistics, indicates the necessity of effective and applicable local traffic management in the southern entrance of the Strait. In this study, Marine Traffic Fast Time Simulation (MTFTS) studies are used and an attempt is made to improve navigation safety by proposing Local Traffic Separation Schemes (LTSS). [ABSTRACT FROM AUTHOR]

In India in the early twentieth century the modern socio-technological phenomenon of traffic brought together many visible and accessible forms of everyday technology. However, in India modern motorized transport had to operate alongside earlier, seemingly ‘pre-modern’, modes of street-life. The emergence of traffic helped foster the expansion of late-colonial policing and the growth of the ‘everyday state’. It stimulated a new sense of a middle class identity and the proper ordering and disciplining of those who used the modern highway. But the technology of traffic was also contested—by those who evaded traffic rules as well as by those who were critical of technological modernity or the rising human cost of traffic accidents. The street at times became a site of open opposition to state authority or, through the deliberate disruption of traffic, a significant location for the exercise of political defiance and control. [ABSTRACT FROM PUBLISHER]

The article discusses the benefits of active traffic management (ATM) strategies in the U.S. The Federal Highway Administration (FHWA) contracted Parsons Brinckerhoff to provide technical assistance and support related to ATM. The goal of an ATM strategy is to dynamically control and manage traffic demand as well as transportation capacity. Some of ATM strategies are speed harmonization, hard-shoulder running and junction control.

Routing configurations that have been optimized for a nominal traffic scenario often display significant performance degradation when they are subjected to real network traffic. These degradations are due to the inherent sensitivity of classical optimization techniques to changes in model parameters combined with the significant traffic variations caused by demand fluctuations, component failures and network reconfigurations. In this paper, we review important sources for traffic variations in data networks and describe tractable models for capturing the associated traffic uncertainty. We demonstrate how robust routing settings with guaranteed performance for all foreseen traffic variations can be effectively computed via memory efficient iterative techniques and polynomial-time algorithms. The techniques are illustrated on real data from operational IP networks. [ABSTRACT FROM AUTHOR]

Real time traffic flow simulation models are used to provide traffic information for dynamic traffic management systems. Those simulation models are supplied by traffic data in order to estimate and predict traffic conditions in unobserved sections of a traffic network. In general, most of recent real time traffic simulators are based on the macroscopic model because the macroscopic model replicates the average traffic behavior in terms of observable variables such as (time-space) flow and speed at a relatively fast computational time. Like other simulation models, an important aspect of the real time macroscopic simulator is to calibrate the model parameters online. The most conventional way of the online calibration is to add a random walk to the parameters to constitute an augmentation of the traffic variables and the model parameters to be estimated. Actually, this method allows the parameters to vary at every time step and, therefore, describes the adaptation of the model to the prevailing traffic conditions. However, it has been reported that the use of the random walk results in a loss of information and an increase of the covariance of parameters, which consequently leads to posteriors that are far more diffuse than the theoretical posteriors for the true parameters. To this end, this article puts forward a Kernel density estimation technique in the calibration process to handle the covariance issue and to avoid the information loss. The Kernel density estimation technique is embedded in the particle filter algorithm, which is extended to the calibration problems. The proposed framework is investigated using real-life data collected in a freeway in England. [ABSTRACT FROM AUTHOR]

To analyze the relative management strategies during regional evacuation and traffic management and the relationship among them, from the global perspective of disaster emergency management, this paper identifies the types, stages of disaster management and major traffic management issues involved during the process of disaster management. Also, the connotation and extension of regional evacuation traffic management are clarified. Finally, an integrated modeling and analysis framework of evacuation traffic management is established, including the disaster scenario analysis, evacuation traffic demand forecasting, evacuation traffic flow analysis, evacuation traffic dynamic assignment model, integrated evacuation traffic management and simulation evaluation of evacuation traffic management plan. This framework can effectively guide the analysis and modeling of regional evacuation traffic management issue and present a significant theoretical anti practical value for improving the efficiency of traffic evacuation in a transportation network. [ABSTRACT FROM AUTHOR]

In this paper, we adopts the means of macroscopic traffic flow simulation to simulate evolution of traffic conditions of the freeway network, including congestion occurrence, transmission and dissipation. Effects of traffic radio based route guidance strategy are also investigated. Visualize output from simulation, such as time-varying trajectories about traffic conditions (speed, flow, etc. ) and snapshots of global traffic network state are given. Simulation of a 3 origin-3 destination freeway network shows that state evolution of traffic network flow is a complex dynamic process. Congestion at local nodes in network (for instance bottlenecks in convergence zones) often leads whole network congestion, which causes traffic delays and little use of road capacity. Macroscopic traffic flow simulation is effective and superior in diagnosis of congestion reasons and in simulating effects of traffic control strategy. This research aims at giving ideas and technical references for design and evaluation of traffic control and management strategies. [ABSTRACT FROM AUTHOR]

Developing a network for cycle traffic is a complex process, particularly in a dense and heavily motor trafficked city such as London. The London Cycle Network Plus has delivered cycle routes on strategic highways, and local cycling stakeholders have assisted in the design process through cycle route implementation and stakeholder plans. Stakeholders were trained in aspects of highway engineering and used the London cycling design standards as a reference tool. The paper summarises the lessons learnt, and concludes that knowledge from stakeholders is needed to help in the design process, and such intense involvement was novel in transport planning. The current proposals for cycle superhighways and other borough transport schemes seek to build on previous participative successes and also emphasise planning issues in the geographical neighbourhood of routes. [ABSTRACT FROM AUTHOR]

The automation of driving tasks is of increasing interest for highway traffic management. The emerging technologies of global positioning and intervehicular wireless communications, combined with in-vehicle computation and sensing capabilities, can potentially provide remarkable improvements in safety and efficiency. We address the problem of designing intelligent intersections, where traffic lights and stop signs are removed, and cars negotiate the intersection through an interaction of centralized and distributed decision making. Intelligent intersections are representative of complex hybrid systems that are increasingly of interest, where the challenge is to design tractable distributed algorithms that guarantee safety and provide good performance. [ABSTRACT FROM PUBLISHER]

This paper describes a new approach that allows us to partition the anthropogenic and natural contributions to heavy metal accumulations in roadside agricultural soils. This approach, combining trend analysis and multivariate statistical analysis, partitions total heavy metals into three components: anthropogenic, natural, and unexplained residual. The approach was applied in a case study in Yixing City, China, to determine the spatial distributions of heavy metal accumulations. The results show that anthropogenic components of Pb, Cu, Zn, and Cd account for 52.4%, 23.04%, 5.09%, and 10.9% of total content, respectively. Spatial distributions of anthropogenic components are characterized by decreasing accumulation with increasing distance from the road. Ranges of influence of traffic for Pb, Cu, and Cd are beyond 300 m, whereas the range of Zn is less than 200 m. The spatial distributions of the four elements' natural components show relatively similar distribution patterns. Assessments of variable partition methods show that the predicted values of Pb, Cu, Zn, and Cd are consistent with their measured values. The anthropogenic components extracted from total contents of heavy metal will be useful for modeling heavy metal accumulations produced by human activities. [ABSTRACT FROM AUTHOR]

An extension of the Colombo phase transition model is proposed. The congestion phase is described by a two-dimensional zone defined around a standard fundamental diagram. General criteria for building such a set-valued fundamental diagram are enumerated and instantiated on several standard fluxes with different concavity properties. The solution to the Riemann problem in the presence of phase transitions is obtained through the design of a Riemann solver, which enables the construction of the solution of the Cauchy problem using wavefront tracking. The free-flow phase is described using a Newell-Daganzo fundamental diagram, which allows for a more tractable definition of phase transition compared to the original Colombo phase transition model. The accuracy of the numerical solution obtained by a modified Godunov scheme is assessed on benchmark scenarios for the different flux functions constructed. [ABSTRACT FROM AUTHOR]

Participants were asked to walk inside the city along a route, which consisted of streets with various amounts of vegetation and various degrees of traffic intensity. The walking speed was measured in eight selected sections. The environmental properties of the sections were estimated by raters, who described a level of naturalness of a place, intensity of traffic, noise, openness of a space, and restorative qualities of a place, as well as emotional reactions in particular sections. Participants tended to walk slightly faster in sections without greenery and with a higher level of traffic than in sections with greenery and with a small level of traffic. Further, it was found that sections, where participants walked slower, had higher restorative qualities (measured by the Perceptual Restorative Scale) and elicited more positive emotions than areas where participants walked faster. The results are discussed in terms of approach-avoidance behavior (Mehrabıan and Russell,1974), as well as with the concept of attention restorative theory (Kaplan and Kaplan,1989). [ABSTRACT FROM AUTHOR]

Accidents on expressway will disturb the normal state of traffic flow, even cause the traffic jam. To disperse effectively the traffic jam, a proper model is needed to simulate the traffic flow under crowded condition. In this paper, the characteristics of individual vehicles in the jam were studied, firstly. Then the rules of current cellular automaton model (CA model) were improved and a new CA model for the traffic jam was brought forward. With the new model, it is possible to simulate the process of traffic jams' propagation and decay, and the rules of the jams' decay can be explored. Lastly, the effects of using different control measures for the jams are investigated. [ABSTRACT FROM AUTHOR]

Identifying applications and classifying network traffic flows according to their source applications are critical for a broad range of network activities. Such a decision can be based on packet header fields, packet payload content, statistical characteristics of traffic and communication patterns of network hosts. However, most present techniques rely on some sort of a priori knowledge, which means they require labor-intensive preprocessing before running and cannot deal with previously unknown applications. In this paper, we propose a traffic classification system based on application signatures, with a novel approach to fully automate the process of deriving signatures from unidentified traffic. The key idea is to integrate statistics-based flow clustering with payload-based signature matching method, so as to eliminate the requirement of pre-labeled training data sets. We evaluate the efficiency of our approach using real-world traffic trace, and the results indicate that signature classifiers built from clustered data and pre-labeled data are able to achieve similar high accuracy better than 99%. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The provisioning of fairness to various network applications is an important Quality-of-Service demand and has thus become a challenging research issue in contemporary communication networks. Deficit Round Robin (DRR) is a promising fair scheduling mechanism owing to its low complexity and excellent ability of achieving a good degree of fairness in terms of throughput. On the other hand, self-similar traffic was found to be pervasively present in communication networks and has great impact on the performance of scheduling systems. However, to the best of our knowledge, there has not been any analytical model reported in the open literature for the DRR mechanism in the presence of self-similar traffic. To fill this gap, this paper analytically investigates the queueing performance of DRR and develops a new analytical model for deriving the upper and lower bounds of the queue length distributions of individual traffic flows in DRR scheduling systems subject to self-similar traffic. Extensive comparison between simulation and analytical results validates the accuracy of the developed model. To demonstrate its applications, the analytical model is used to investigate the effects of packet size on the performance of the queueing system. The developed model is further applied to study the configuration of weights of individual traffic flows. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we study traffic equilibrium problems with capacity constraints of arcs and derive a sufficient condition of weak vector equilibrium flows. Based on this sufficient condition, we establish the existence and essential components of the solution set for traffic equilibrium problems with capacity constraints of arcs. [Copyright &y& Elsevier]

Traffic modeling and simulation plays an important role in the area of Network Monitoring and Analysis, for it provides practitioners with efficient tools to evaluate the performance of networks and of their elements. This article focus on the traffic generated by a single source, providing an overview of what was done in the field and studying the statistical properties of the traffic produced by a personal computer, including analysis of the autocorrelation structure. Different distributions were fitted to the interarrival times, packet sizes, and byte count processes with the goal of singling out the ones most suitable for traffic generation. [ABSTRACT FROM AUTHOR]

Air traffic management is a complex hierarchical system. Hierarchy levels can be defined according to decision making time horizon or to analysis area volume. For medium time horizon and wide analysis area, the air traffic flow management (ATFM) services were established. Their main task is to properly co-ordinate air traffic in airspace, so as to minimize delays arising in congested sectors. Those services have to assure high safety level in the same time. Thus it is very complex task, with many goals, many decision variables and many constraints. In the paper a short review of selected methods developed for aiding air traffic flow management services is presented. More detailed description of an original dynamic method is given. This method is based on stochastic capacity and scenario analysis. The discrete multi-criterion programming problem was formulated on the assumption that expected values of airport capacity in discrete future moments in time are known. It leads to determination of the proper moment of passing the information of airport capacity change to ATFM services. Some problems in utilization of presented methods are also pointed out, so are the next research possibilities. [ABSTRACT FROM AUTHOR]

Traffic systems are often highly populated discrete event systems that exhibit several modes of behavior such as free flow traffic, traffic jams, stop-and-go waves, etc. An appropriate closed loop control of the congested system is crucial in order to avoid undesirable behavior. This paper proposes a macroscopic model based on continuous Petri nets as a tool for designing control laws that improve the behavior of traffic systems. The main reason to use a continuous model is to avoid the state explosion problem inherent to large discrete event systems. The obtained model captures the different operation modes of a traffic system and is highly compositional. In order to handle the variability of the traffic conditions, a model predictive control strategy is proposed and validated. [ABSTRACT FROM AUTHOR]

The article discusses the concept of introducing proactive traffic management to enhance freeway safety and operation in the U.S. A crash risk assessment framework for Interstate 4 in Florida is presented. The research addresses rear-end crashes in medium to high-speed traffic conditions. It is concluded that spatial speed differential in the direction of travel contributes drastically to rear-end crash risk.

This study focused on the assessment of pedestrianization policy in Vigan City, a UNESCO World Heritage Site. It aimed to characterize the area and pedestrian movements on implementation of pedestrianization scheme, analyze the perception of respondents on the necessity, acceptability, and impact of pedestrianization scheme, and test the relationships between perceptions and characteristics of respondents. There were 480 respondents chosen randomly. It made use of the exploratory and descriptive method of research. The results showed a very high level of necessity and acceptability of the use of pedestrianization in the city of Vigan. It is recommended that the city government of Vigan should enact an ordinance for the implementation of a “give way to pedestrians” policy in all the streets in the heart of Vigan City for maximum safety. The city government should also adopt some environmentally sustainable transport strategies in the pursuit of a sustainable development of the city of Vigan without sacrificing its legacy as world heritage site. [ABSTRACT FROM AUTHOR]

Abstract: During the last decade, there has been a substantial interest in how to determine the optimal number and locations of traffic counters for origin–destination (OD) trip matrices estimation. On the contrary, the optimal allocation of plate scanning devices has received very limited attention, even though several authors have demonstrated that plate scanning (route identification) techniques are much more informative than those based on traditional link count information. This paper provides techniques for obtaining the optimal number and location of plate scanning devices for a given prior OD distribution pattern under different situations, i.e. maximum route identifiability or budget constraints. Two rules analogous to the counting location problem are developed, and several integer linear programming models fulfilling these rules are proposed. The proposed methods are finally illustrated by their application into Nguyen–Dupuis and Cuenca networks. [Copyright &y& Elsevier]

The Highway Capacity Manual 2000 indicates that the capacity of two-lane two-way highways (TLTWHWs) is 1,700 pcph for a single direction and 3,400 pcph for both directions. There are no capacity estimates provided for different traffic conditions such as varying percentages of no-passing zones and varying traffic distributions between the two directions of travel. Previous research has reported that capacity conditions for TLTWHW are very difficult to observe in the field while none of the existing simulation models can report capacity for TLTWHW. This paper briefly describes a new TLTWHW simulation model called TWOSIM that is developed, verified, compared to TWOPAS and highway capacity software (HCS) and used for the estimation of capacity for TLTWHW under a variety of prevailing traffic and geometric conditions. These include percentage of traffic per direction, presence of a passing zone, a horizontal curve, a driveway, an upgrade, and heavy vehicles. Capacity of TLTWHW under base conditions is estimated to be 1,800 pcphpl at 64 kph (40 mph) average free-flow speed, 2,000 pcphpl at 80 kph (50 mph), and 2,100 pcphpl at 96–112 kph (60–70 mph). The presence of passing zones was not found to have an effect on capacity. When a driveway or horizontal curve or upgrade is present, the capacity reduction ranges between 3 and 30% when there are no trucks and may reach up to 40% when trucks are present in the traffic stream. [ABSTRACT FROM AUTHOR]

Recently, a multi-objective model for locating the automatic vehicle identification (AVI) readers in a transportation network was proposed by the authors along with its solution procedure. The model locates the AVI readers by simultaneously considering three objectives: the equipment and installation cost (e.g. number of AVI readers), the coverage of the AVI system (e.g. number of origin-destination (O-D) pairs), and the amount/quality of travel information obtained (e.g. number of AVI readings). However, only a single travel demand pattern for a certain time period, such as the evening peak hour, was considered in determining the AVI reader locations. Therefore, the recommended AVI system may not be able to guarantee the amount of travel information gathered during other time periods. This study extends our previously proposed model by developing three scenario-based models to accommodate different travel demand patterns observed during the whole day. A case study is provided to illustrate the applicability of the new models and the robustness of the AVI system designed by considering different travel demand patterns. [ABSTRACT FROM AUTHOR]

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Abstract: Background: Existing traffic variables used for predicting NO2 in epidemiological studies are either difficult to acquire or explain only a small proportion of the variance. The purpose of this study was to develop and validate a new predictor, weighted road density, which combines the maximum amount of information related to traffic into a single variable without the requirement of obtaining traffic counts for a given area. Method: Two week NO2 samples were collected using the readings of up to 32 passive samplers on 3 separate rounds between September and December 2006 and again in 2007. Several types of traffic related explanatory variables based on traffic counts, distance to main road and the proposed weighted road density were constructed using GIS software, and tested for association with the NO2 samplers. Assessment of the best model was based on R 2 values, as well as leave-one-out cross validation. Results: The weighted road density variable and the density variable based on traffic counts resulted in a similar R 2 (0.59) for predicting NO2, although weighted road density was much easier to construct and outperformed other variables such as distance to main road. Conclusion: As well as being a powerful predictor for use in a land use regression model, weighted road density can be used as a proxy for exposure to traffic-related pollution, for use in circumstances where direct measurements of pollutant levels are not feasible or are not required. [Copyright &y& Elsevier]

The article presents the author's insights on being the recipient of the 2009 Theodore M. Matson Memorial Award. He states that his career has been benefited from others' reluctance to push the message on how important transportation is to the economy and to people's lives. He discusses traffic congestion which is an issue that affects research engineers. He also tackles the value of transportation and suggests to reduce the congestion through projects and policies of agencies and individuals.

Previous works on traffic-flow dynamics on complex networks have mostly focused on continuous phase transition from a free-flow state to a locally congested state as a parameter, such as the packet-generating rate, is increased through a critical value. Above the transition point congestion occurs on a small subset of nodes. Utilizing a conventional traffic-flow model based on the packet birth-death process and more importantly, taking into account the fact that in realistic networks nodes have only finite buffers, we find an abrupt transition from free flow to complete congestion. Slightly below the transition point, the network can support the maximum amount of traffic for some optimal value of the routing parameter. We develop a mean-field theory to explain the surprising transition phenomenon and provide numerical support. Furthermore, we propose a control strategy based on the idea of random packet dropping to prevent/break complete congestion. Our finding provides insights into realistic communication networks where complete congestion can occur directly from a free-flow state without any apparent precursor, and our control strategy can be effective to restore traffic flow once complete congestion has occurred. [ABSTRACT FROM AUTHOR]

Electric vehicles are for cities an important factor for improving the traffic in urban areas and creating a healthier environment. It is a dream for human being, city traffic without exhausting gas and low noise. Today's technology includes modern motor design influenced by power electronics and automotive views, energy sources performing better and better to match acceptable vehicle. Nowadays studies on energy storage systems have been going on. In this studies, energy storage technologies are considered to be the most important application area. For more than ten years a number of experiments and demonstration plants have been done in all over the world. Also, storage technologies application and their importance for electric vehicle are explained. In this paper, we focus on the electric vehicle, energy storage technologies in EV, elements of the electric vehicle and their propulsion systems. [ABSTRACT FROM AUTHOR]

Given the dynamic character of public transportation systems, it is difficult to respect accurately theoretical timetables. In real conditions, many disturbances may occur in transportation networks and cause troubles in vehicle schedules. In order to keep transportation systems as stable as possible, a real-time traffic regulation has to be performed by optimizing some regulation criteria that represent exploitation objectives. In this article, we deal with the regulation problem as a multi-criteria optimization one for which we propose a nonaggregative approach based on multi-agent systems. For a given disturbance, the approach firstly ensures an anytime generation of Pareto solutions set by using a distributed Tabu search. Then, the best compromise solution is determined through a multi-criteria evaluation process. Therefore, two multi-criteria evaluation procedures are also suggested: Plurality voting procedure and fuzzy-based procedure. In order to assess the distributed approach, an experimental study was performed on the base of real scenarios. [ABSTRACT FROM AUTHOR]

Advances in wireless communications allow setting up communication links between vehicles for the exchange of information between them. Such vehicular ad hoc networks (VANETs) are important to enhance traffic safety since critical environmental conditions, such as road or traffic conditions, can be rapidly exchanged between vehicles in VANETs. However, to be useful for the driver, the information must be reliable, i.e., with great probability, the received information indeed reflects the actual situation. One approach to this is to regard information as reliable if it is confirmed by various sources. To achieve this, messages received must be distinguishable. This may become a threat against the privacy of drivers since by observing messages, vehicles may be traced. In this paper, we address the mentioned problems. We base the reliability of information on the number of different sources that confirmed specific information, and that number must be greater than a given threshold. We address the nontraceability by letting vehicles change their identity frequently. Our approach scales with respect to storage on the vehicle, as well as management of identities at a certification authority. [ABSTRACT FROM AUTHOR]

Starting from the instability diagram of a traffic flow model, we derive conditions for the occurrence of congested traffic states, their appearance, their spreading in space and time, and the related increase in travel times. We discuss the terminology of traffic phases and give empirical evidence for the existence of a phase diagram of traffic states. In contrast to previously presented phase diagrams, it is shown that “widening synchronized patterns” are possible, if the maximum flow is located inside of a metastable density regime. Moreover, for various kinds of traffic models with different instability diagrams it is discussed, how the related phase diagrams are expected to approximately look like. Apart from this, it is pointed out that combinations of on- and off-ramps create different patterns than a single, isolated on-ramp. [ABSTRACT FROM AUTHOR]

Events and incidents are relatively rare, but they often have a negative impact on traffic. Reliable travel demand predictions during events and incident detection algorithms are thus essential. The authors study link flows that were collected throughout the Dutch city of Almelo. We show that reliable, event-related demand forecasting is possible, but predictions can be improved if exact start and end times of events are known, and demand variations are monitored conscientiously. For incident detection, we adopt a method that is based on the detection of outliers. Our algorithm detects most outliers, while the fraction of detections due to noisy data is only a few percent. Although our method is less suitable for automatic incident detection, it can be used in an urban warning system that alerts managers in case of a possible incident. It also enables us to study incidents off-line. In doing so, we find that a significant fraction of traffic changes route during an incident. [ABSTRACT FROM AUTHOR]