Increase In Traffic Density Research Articles

Effect of traffic density on drivers’ lane change and overtaking maneuvers in freeway situation—A driving simulator–based study

Objective: The aim of this study is to examine the effect of traffic density on drivers’ lane change and overtaking maneuvers. The differences between drivers’ left and right lane changing/overtaking maneuvers were also investigated.Method: A driving simulator experiment was conducted and 24 participants took part in this experiment. Based on the driving simulation data, lane change frequency, time duration, average speed, and acceleration were extracted as key variables of lane change maneuvers; overtaking frequency, overtaking duration, initial overtaking distance and headway, instantaneous speed, and acceleration before overtaking were analyzed as the key overtaking variables. One-way repeated measures analysis of variance (ANOVA), the Friedman test, and the Wilcoxon signed rank test were adopted for hypothesis tests with a significance level of .05. Further pairwise comparisons were performed with a Bonferroni correction for multiple comparisons.Results: Some significant differences in lane change and overtake behaviors were observed among different traffic densities: (1) both lane change and overtaking frequencies significantly increase with traffic density; (2) the average lane change acceleration and instantaneous overtaking acceleration significantly increase with traffic density; (3) as the traffic density increases, the initial overtaking distance and headway decrease. As for the effect of the directions of maneuvers, the (1) time duration of lane change and overtaking from the right side was significantly shorter than that from the left side; (2) right initial overtaking distance/headway was smaller than that of the left side; (3) right instantaneous overtaking acceleration was significantly higher than the left instantaneous acceleration.Conclusions: The results showed that as traffic density increases, drivers’ lane changing and overtaking intentions are enhanced. Both initial overtaking distance and headway decrease with traffic density, which might influence road safety. In addition, drivers do not show a preference on the directions of lane change or overtaking according to frequency. However, drivers tend to be more decisive and reckless when overtaking on the right because of a smaller distance/headway before overtaking, higher instantaneous acceleration, and a more restricted field of view compared with overtaking on the left.

Incidence and mortality risk for respiratory tract cancer in the city of São Paulo, Brazil: Bayesian analysis of the association with traffic density

BackgroundThere is evidence that exposure to traffic-related air pollution is related to the incidence of and mortality associated with lung cancer. The aim of this study was to perform a spatial analysis, with a Bayesian approach, to test the hypothesis that high traffic density is associated with increased respiratory tract cancer incidence and mortality risk among individuals over 20 years of age residing in the city of São Paulo, Brazil. MethodsWe employed data from two different databases: the São Paulo Municipal Population-Based Cancer Registry (2002–2011 cancer incidence data); and the Mortality Database of the São Paulo Municipal Health Department (2002–2013 cancer mortality data). The relationships between the number of cases of respiratory tract cancer in each area analyzed and the standardized covariates—traffic density and the Municipal Human Development Index (MHDI)—were evaluated with a Besag–York–Mollié ecological model with relative risks (RRs) estimates. ResultsPer 1-unit standard-deviation increase in traffic density and in the MHDI, the RR for respiratory tract cancer incidence was 1.07 (95% CI: 1.02–1.13) and 1.25 (95% CI: 1.18–1.32), respectively, whereas the RR for mortality was 1.04 (95% CI: 0.99–1.09) and 1.23 (95% CI: 1.16–1.30), respectively. ConclusionOur findings support the hypothesis that residing in areas with high traffic density is associated with increased respiratory tract cancer incidence and mortality risk in the city of São Paulo.

Analysis of flight conflicts in the Chinese air route network

The increase in economic exchange, brought about by globalization and leaps of progress in science and engineering, has led to a sharp increase in air traffic density. As a consequence, airspace has become increasingly crowded, and limitations in airspace capacity have become a major concern for the future development of air travel and transportation. In this paper, we adopt methods of network science to analyze flight conflicts in the Chinese air route network. We show that air conflicts are distributed heterogeneously along the waypoints of the Chinese air route network. In particular, the frequency of flight conflicts follows an exponential distribution. The time-space investigation of flight conflicts shows that they are concentrated at specific regions of the Chinese air route network and at specific time periods of the day. Our work offers fascinating insights into one of the world's largest and most busiest air route networks, and it helps us mitigate flight conflicts and improve air traffic safety.

A Marine Information System for Environmental Monitoring: ARGO-MIS

Sea shipping routes have become very crowded and this, coupled with an always increasing demand of oil based products, contributes to the increase in maritime traffic density, as a consequence pollution risks have increased. Therefore, it is important to have information systems capable of detecting and monitoring environmental endangering situations like oil spills at sea. In this paper, a Marine Information System, acting as an integrated and inter-operable monitoring tool is proposed and discussed. The discussion focuses on a system that is able to integrate different data acquired from various electronic sensors, and that is inter-operable among marine operators and ship traffic authorities. The available data on the system are all geo-referenced, and flows seamlessly through the system, where they are integrated in a consistent and usable manner. An important result of this integration is the capability to produce a collection of proactive services such as Decision Support ones, which can be used to improve the functionalities and facilities concerned in an intervention operation. Through the implementation of these services, we aim to demonstrate how an efficient environmental management system could benefit from being supported by a Marine Information System that can provide the dynamic links between different data, models and actors.

Analysis and Performance Optimization of LoRa Networks With Time and Antenna Diversity

Low power wide area network (LPWAN) technologies are increasingly catching the attention of the Internet-of-Things market and have brought the need for reliable knowledge about the performance of such networks. This paper is concerned with the performance and scalability of LoRa networks, a leading LPWAN technology. Several recently published articles have analyzed the ability of LoRa networks to scale, i.e., their ability to support increased traffic and number of nodes. This paper proposes to employ message replication and gateways with multiple receive antennas to achieve, respectively, time and spatial diversity. The paper presents the proposed schemes and evaluates them through theoretical analysis and computer simulations. Results show that LoRa networks are highly sensitive to the increase in user and traffic density, but both message replication and multiple antennas can enhance performance. Message replication has an optimum number of message copies for each network configuration, and its utilization is more beneficial in low-density networks, while the use of multiple receive antennas at the gateway is always beneficial.

Spatio-temporal Network-Constrained Trajectory Data Model and Service Reliability Assessment

ABSTRACTDue to urbanization and increase in traffic density, provision of efficient public transport facility is a major component of planning and development. The spatio-temporal data of vehicles’ movement have mainly led to mobility pattern analysis, which eventually reveal new information about the efficiency of transport service. This research focuses on extracting mobility patterns of bus service for students in Lahore City. Trajectory data collected through GPS survey have been processed by using MYSQL spatial database applications and HTML to identify areas in entire route of bus service causing delay. Three different types of delay have been calculated, namely stop delay, simple path delay, and path repeated delay. The entire analysis results reveal that mainly the delay is caused at start segments of planned route or the last segment of stop route. The major cause of delay is bus movement on tertiary roads through congested commercial areas.

Computational Investigation of Varying Plate-Line Geometry and Placement on Wake Vortex Dissipation

One of the bottlenecks for the recent increase in air traffic density is near the airport, where wake vortices, bounded by the terrain, could easily rebound into the landing corridor and remain there for a long period of time while maintaining their strength. The threat of near-ground wake vortex could be mitigated by the plate-line technology, which places a series of thin plates across the landing corridor before the runway; the technology was shown to significantly reduce the time it takes for wake vortex dissipation. The current investigation aims to better understand factors such as plate dimension and lateral position influences on the generation of secondary vortex structure and ultimately the dissipation rate of a wake vortex pair. It is found that the wake dissipation could be sped up further by optimizing the lateral position of the plate relative to the obstacle–vortex contact location, while the height of the plate could be significantly reduced without noticeably affecting the performance of the obstacle set.

Development of potential methods for testing congestion control algorithm implemented in vehicle-to-vehicle communications

ABSTRACTObjective: A channel congestion problem might occur when the traffic density increases because the number of basic safety messages carried on the communication channel also increases in vehicle-to-vehicle communications. A remedy algorithm proposed in SAE J2945/1 is designed to address the channel congestion issue by decreasing transmission frequency and radiated power. This study is to develop potential test procedures for evaluating or validating the congestion control algorithm.Methods: Simulations of a reference unit transmitting at a higher frequency are implemented to emulate a number of onboard equipment (OBE) transmitting at the normal interval of 100 ms (10 Hz). When the transmitting interval is reduced to 1.25 ms (800 Hz), the reference unit emulates 80 vehicles transmitting at 10 Hz. By increasing the number of reference units transmitting at 800 Hz in the simulations, the corresponding channel busy percentages are obtained. An algorithm for Global Positioning System (GPS) data generation of virtual vehicles is developed for facilitating the validation of transmission intervals in the congestion control algorithm.Results: Channel busy percentage is the channel busy time over a specified period of time. Three or 4 reference units are needed to generate channel busy percentages between 50 and 80%, and 5 reference units can generate channel busy percentages above 80%. The proposed test procedures can verify the operation of congestion control algorithm when channel busy percentages are between 50 and 80% and above 80%. By using a GPS data generation algorithm, the test procedures can also verify the transmission intervals when traffic densities are 80 and 200 vehicles in a radius of 100 m. A suite of test tools with functional requirements is also proposed for facilitating the implementation of test procedures.Conclusions: The potential test procedures for a congestion control algorithm are developed based on the simulation results of channel busy percentage and the GPS data generation algorithm. The test tools can examine the requirement compliance automatically and objectively. The required number of reference units should be further validated using real OBEs before implementing these potential test procedures.

Equilibrium traffic dynamics in a bathtub model: A special case

For a quarter century, a top priority in transportation economics has been to develop models of rush-hour traffic dynamics that incorporate hypercongestion – situations of heavy congestion where throughput decreases as traffic density increases. Unfortunately, even the simplest models along these lines appear in general to be analytically intractable, and none of the models that have made approximations in order to achieve tractability has gained widespread acceptance. This paper takes a different tack, developing an analytical solution for a special case – a no-toll equilibrium in an isotropic downtown area with identical commuters, Greenshields' congestion technology, and the α−β cost function (no late arrivals permitted). This is followed by a discussion of directions for future research.

Intelligent Transport System: A Progressive Review

Objectives: Increase in traffic density in the world results in more and more congestion, air pollution and accidents. Hence Intelligent Transport System (ITS) has been emerged as a solution to various transport related issues. The aim of this research paper is to conduct systematic analysis on ITS. Methods/Statistical Analysis: ITS is defined as the set of applications which are advance and aim to apply intelligent information and communication technologies in order to provide services for transport and traffic management. ITS have combined various technologies such as Data collection, Communication, Data Mining, Machine Learning, Artificial Intelligence and Database Management. By combining these information technologies ITS have provided various applications such as Traffic control, Fault detection systems, In-vehicle information and navigation systems and driver assistance systems. Findings: We have considered the most relevant published work from 2008 onward relative to our objective from different popular digital libraries. We have summarized this work into issues in ITS and techniques used to solve them. Application/Improvements: It has been found that by combining various new technologies such as agent based computing, cloud computing, VANETS etc. ITS have become very efficient to solving transport related issues in smart cities.

Turkish Republic of Northern Cyprus Vessel Traffic Services (TRNC-VTS)

The first Vessel Traffic Service (VTS) started in 1949 in the Liverpool Port (UK) and it continued in Netherlands in 1956. In Turkey, planning and management of the marine traffic using the waterways and ports in Turkey started with Turkish Straits VTS which came into service in 2003 due to the increase in traffic density enhance its effectiveness and necessity every year. Feasibility studies in five new areas have been initiated for the establishment of the VTS system by force of the strategic decision taken by the maritime authority in 2008. These areas are; Izmit Bay, Izmir Bay and Aliaga Region, Gulf of Iskenderun and Mersin. Monitoring the marine traffic has an important place as the Turkish Republic of Northern Cyprus (TRNC) is an important transition point in the Eastern Mediterranean region. For this reason, in this study the impact assessment and necessity of the establishment of a VTS to be located in the TRNC were evaluated by using Environmental (PEST: Political, Economic, Social, Technological) and SWOT (Strengths, Weakness, Opportunities, Threats) Analyses. In addition, the suitability of the possible locations of Traffic Monitoring Stations (TMS) has been examined by the field study. Evaluation of TRNC VTS in geographical and strategic terms will benefit from the opportunities and facilities that both the Republic of Turkey and the TRNC will have as a part of the effect of VTS against the embargo imposed on the TRNC in the world. Three appropriate VTS TMSs have been chosen as a result of the field study carried out for 10 determined TMSs; Cape Kormakitis, Cape Apostolos Andreas and Famagusta. It is also concluded that it would be appropriate to plan the Famagusta Station as VTS Centre. It is assumed to monitor and track the vessels in the zones out of the coverage area of these stations by Automatic Identification System (AIS). Safety and security in the shipping, protection of navigation, life, property and the marine environment of the region will be enhanced by monitoring the vessels passing particularly through this region and by making use of the opportunities provided by technology in accordance with national and international regulations.

Small-area spatiotemporal analysis of pedestrian and bicyclist injuries in New York City.

This study quantifies the spatiotemporal risk of pedestrian and bicyclist injury in New York City at the census tract level over a recent 10-year period, identifies areas of increased risk, and evaluates the role of socioeconomic and traffic-related variables in injury risk. Crash data on 140,835 pedestrian and bicyclist injuries in 1908 census tracts from 2001 to 2010 were obtained from the New York City Department of Transportation. We analyzed injury counts within census tracts with Bayesian hierarchical spatial models using integrated nested Laplace approximations. The model included variables for social fragmentation, median household income, and average vehicle speed and traffic density, as well as a spatially unstructured random effect term, a spatially structured conditional autoregression term, a first-order random walk-correlated time variable, and an interaction term for time and place. Incidence density ratios, credible intervals, and probability exceedances were calculated and mapped. The yearly rate of crashes involving injuries to "pedestrians" (including bicyclists) decreased 16.2% over the study period, from 23.7 per 10,000 population to 16.2 per 10,000. The temporal term in the spatiotemporal model indicated that much of the decrease over the study period occurred during the first 4 years of the study period. Despite an overall decrease, the model identified census tracts that were at persistently high risk of pedestrian injury throughout the study period, as well as areas that experienced sporadic annual increases in risk. Aggregate social, economic, and traffic-related measures were associated with pedestrian injury risk at the ecologic level. Every 1-unit increase in a standardized social fragmentation index was associated with a 19% increase in pedestrian injury risk (incidence density ratio = 1.19 [95% credible interval = 1.16 - 1.23]), and every 1 standardized unit increase in traffic density was associated with a 20% increase in pedestrian injury risk (1.20 [1.15 - 1.26]). Each 10-mile-per-hour increase in average traffic speed in a census tract was associated with a 24% decrease in pedestrian injury risk (0.76 [0.69 - 0.83]). The risk of a pedestrian or bicyclist being struck by a motor vehicle in New York City decreased from 2001 to 2004 and held fairly steady thereafter. Some census tracts in the city did not benefit from overall reductions or experienced sporadic years of increased risk compared with the city as a whole. Injury risk at the census tract level was associated with social, economic, and traffic-related factors.

A network level connectivity robustness measure for connected vehicle environments

This study introduces a new CONnectivity ROBustness model (CONROB) to assess vehicle-to-vehicle communication in connected vehicle (CV) environments. CONROB is based on Newton’s universal law of gravitation and accounts for multiple factors affecting the connectivity in CV environments such as market penetration, wireless transmission range, spatial distribution of vehicles relative to each other, the spatial propagation of the wireless signal, and traffic density. The proposed methodology for the connectivity robustness calculation in CONROB accounts for the Link Expiration Time (LET) and the Route Expiration Time (RET) that are reflected in the stability of links between each two adjacent vehicles and the expiration time of communication routes between vehicles. Using a 117sq-km (45-square mile) network in Washington County, located west of Portland city, Oregon, a microscopic simulation model (VISSIM) was built to verify CONROB model. A total of 45 scenarios were simulated for different traffic densities generated from five different traffic demand levels, three levels of market penetration (5%, 15%, and 25%), and three transmission range values [76 (250), 152 (500), and 305 (1000)m (ft)]. The simulation results show that the overall robustness increases as the market penetration increases, given the same transmission range, and relative traffic density. Similarly, the overall connectivity robustness increases as the relative traffic density increases for the same market penetration. More so, the connectivity robustness becomes more sensitive to the relative traffic density at higher values of transmission range and market penetration. Multiple regression analysis was conducted to show the significant effect of relative traffic density, transmission range, and market penetration on the robustness measure. The results of the study provide an evidence of the ability of the model to capture the effect of the different factors on the connectivity between vehicles, which provides a viable tool for assessing CV environments.

Exposure to traffic and early life respiratory infection: A cohort study

We examined whether proximity to a major roadway and traffic density around the home during pregnancy are associated with risk of early life respiratory infection in a pre-birth cohort in the Boston area. We geocoded addresses for 1,263 mother-child pairs enrolled during the first trimester of pregnancy in Project Viva during 1999-2002. We calculated distance from home to nearest major roadway and traffic density in a 100 m buffer around the home. We defined respiratory infection as maternal report of ≥1 doctor-diagnosed pneumonia, bronchiolitis, croup, or other respiratory infection from birth until the early childhood visit (median age 3.3). We used relative risk regression models adjusting for potential confounders to estimate associations between traffic exposures and risk of respiratory infection. Distance to roadway during pregnancy was associated with risk of respiratory infection. In fully adjusted models, relative risks (95% CI) for respiratory infection were: 1.30 (1.08, 1.55) for <100 m, 1.15 (0.93, 1.41) for 100 to <200 m, and 0.95 (0.84, 1.07) for 200 to <1,000 m compared with living ≥1,000 m away from a major roadway. Each interquartile range increase in distance to roadway was associated with an 8% (95% CI 0.87, 0.98) lower risk, and each interquartile range increase in traffic density was associated with a 5% (95% CI 0.98, 1.13) higher risk of respiratory infection. Our findings suggest that living close to a major roadway during pregnancy may predispose the developing lung to infection in early life. Pediatr Pulmonol. 2015; 50:252-259. © 2014 Wiley Periodicals, Inc.

A Numerical Study on the Influencing Parameters of Tire-Acoustic Cavity

With the increase in traffic density and speed of motor vehicles tire noise became an important area of research. A number of researchers have worked in the last decade to understand noise due to tires. It is important to identify different noise generation mechanisms that contribute to the tire noise and find a way to reduce it. In the present study, the noise generated by the acoustic cavity of the tire is taken into consideration. A non-linear finite element (FE) model using Abaqus has been developed for determining the acoustic pressure in the air cavity, when subjected to harmonic excitation. The influence of the inflation pressure and vehicle load on the tire acoustic cavity is studied for a passenger car radial tire (PCR) 175/70R13.

The effect of moving bottlenecks on a two-lane traffic flow

In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference (FVD) model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to reproduce the vehicular lane changing behavior. Using this model, we derive the fundamental current—density diagrams for the traffic flow with the effect of moving bottleneck. Moreover, typical time—space diagram for a two-lane highway shows the formation and dissipation of a moving bottleneck. Results demonstrate that the effect of moving bottleneck enlarges with the increase of traffic density, but the effect can be reduced by increasing the maximum velocity of heavy truck. The effects of multiple moving bottlenecks under different conditions are investigated. The effect becomes more remarkable when the coupling effect of multiple moving bottlenecks occurs.

Lichens as biomonitors of sulphur dioxide and nitrogen dioxide pollution in Colombo and suburbs

Biological monitoring is an efficient and inexpensive method for monitoring air quality. Studies haveconfirmed that Iichens are among the most rei iable accumulators of airborne inorganic contaminants.As limited research has been done in tropics with regard to biological monitoring, a study was carriedout to monitor lichen diversity and distribution in selected locations in Colombo and its suburbs.Thirty one sites located on six radial transects diverging from Colombo Fort were selected for thisstudy. Eight trees from three trees species, (Cocos nucifera, Mangifera indica, and Artocarpusheterophyllus) within each site (1 km ') were chosen for the study. Coverage and frequency ofcorticolous all lichens found on selected trees were recorded by using 250 em- grids. After studyingtheir morphology, anatomy, reproductive structures and chemistry, lichens collected were identifiedusing keys. In addition, land use pattern, traffic density, pH of substrates, exposure levels of thesesites to light were also recorded. Ambient SO, and NO, levels at each site were determined usingpassive samplers having filter pads coated with-the absorbing reagents, ethylene glycol and acetone,for SO, and Nal, NaOH and Ethylene glycol for NO,. Data were statistically analyzed by using themean comparison, correlation and by principal component analysis to investigate relationship betweendiversity of Iichens and environmental parameters.Forty seven genera of lichens were identified, out of them ten genera are sensitive to air pollutants.The highest atmospheric SO, and NO, levels (48.35/lg/m1 and 42.825~lg/mJ) as well as the lowestlichen diversity (0.8374) were recorded from the site located in Colombo Fort. When land use patternchanged from village to urban and with increase of traffic density of sites, diversity oflichens reducedsignificantly. The relationship between diversity oflichens and levels of SO, and NO, was negativelycorrelated but significant only with levels of NO, Further, a significant negative correfation was foundbetween the pH of substrates and levels of SO, and NO,. Principal component analysis revealed thatprincipal component I(PC I), PC2 and PC3 explain 38%, 20% and 15% of the total variation in thedata set respectively. Biplot developed by PC I vs PC2 revealed that low lichen diversity class isclearly separated from other classes due to increased concentrations of SO" NO, land use patternand the traffic density, all of which are included in PC I. Bark pH values "of Cocos nucifera andArtocarpus heterophyllus that are represented by PC2 also had contributed to above grouping.Index of atmospheric purity (lAP) values increased along all transect with gradual decrease of SO,and N021eveis when moving away from the city.Absence of several pollutant sensitive tropical lichens and decrease of lichen diversity in sites withhigh levels of SO, and NO" indicate that tropical lichens have the potential to be used as indicators inair pollution monitoring work.

Roadside Plants as Bio-indicators of Urban Air Pollution

This paper describes air pollution tolerance among roadside plants exposed to varying degrees of vehicular pollutants. Evaluation of air pollution tolerance index (APTI) of 10 selected wild plant species was carried out to assess their response to ambient levels of air pollutants along the busy roadways of Bangalore. Four parameters namely total chlorophyll, ascorbic acid, pH of leaf extract and relative water content were determined and computed together to signify air pollution tolerance index (APTI) of plants. The observed significant reduction in total chlorophyll, ascorbic acid and relative water content showed inverse relationship with traffic density. Similarly, pH of leaf extract followed an exponential decrease with increase in traffic density and drifted towards acidic range. Comparison of APTI values from control to polluted sites revealed maximum reduction in Bougainvillea spectabilis while least change was noted in Peltophorumpterocarpum. Among the plants studied maximum net per cent reduction of APTI over control was seen in Bougainvillea spectabilis and Ageratum conyzoides and are considered to be sensitive species. While Peltophorumpterocarpum and Portulacaoleraceaeare tolerant species since they have shown least per cent reduction in APTI.

A Crash Risk Estimation Model for Urban Expressway Basic Segments Considering Geometry, Traffic Flow and Ambient Conditions

This study aims at developing a crash risk estimation model (CREM) considering the interaction of geometry, traffic flow and ambient conditions for basic segments of Nagoya Urban Expressway. A matched case-control study is firstly designed separately for three traffic conditions; low-density, high-density uncongested and congested regimes. Based on these case-control samples, conditional logistic regression is then applied and the CREM is finally developed. The results reveal that the model has statistical significance and acceptable goodness-of-fit, with 86.6%, 80.5% and 70.2% of predictive performance for each of the three traffic conditions, respectively. Regarding crash influencing factors, with the increase of traffic density, the significance of horizontal geometry affecting crash becomes lower. In contrast, the contribution of vertical geometry to crash risk is on the rise. Meanwhile, the effect of average speed on crashes gets more significant. Besides, nighttime or holiday can increase the relative risk compared to daytime or weekday, respectively.

Intelligent Ambulance Traffic Assistance System

With the increase in traffic road density, several causalities occur due to delay in taking a patient to the hospital in an ambulance. In this paper, we have developed an algorithm to find the shortest path to reach the required destination. As required the software will identify the present location of the vehicle and ask the user for the destination. Then it will show all the available paths, highlighting the shortest one or in several cases the most optimum one. Further we made the traffic signals automated for special vehicles like an ambulance or a fire-engine such that the signals will go green for the ambulance as it comes in the vicinity of the traffic signal, thus providing them with a clear path to reach its destination. The original signal is restored as soon as the ambulance goes undetected by the Bluetooth scanner of the traffic signal.