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Against the background of global warming, permafrost areas are facing increasing thawing, and the threat to the surface of the Qinghai–Tibet Engineering Corridor (QTEC) is serious. It is imperative to understand the current surface deformation and analyze the changes spatiotemporal characteristics for future warnings. At present, observation of a long time series and overall coverage of vertical ground deformation in QTEC are lacking. This paper takes the permafrost deformation of the QTEC as its research object. It uses the pretreated LiCSAR product and combines it with the LiCSBAS package to obtain monitoring results of the long time series deformation of the engineering corridor's surface. The SAR image acquisition date is taken as the constraint, the results covering the whole processing area are selected, and then the vertical deformation information covering the entire engineering corridor area by ignoring the north–south displacement is calculated. The results show that the surface of the study area, as a whole, slightly subsided between May 2017 and March 2022, and the vertical deformation rate was mostly distributed at −27.068 mm/yr − 18.586 mm/yr, with an average of −1.06 mm/yr. Vertical deformation dominated at 52.84 percent of the study area, of which settlement accounted for 27.57 percent and uplift accounted for 25.27 percent. According to the statistics of the normal distribution of deformation velocity per pixel, a total of 77% of the engineering corridor was stable, with a vertical deformation rate between −6.964 mm/yr and −4.844 mm/yr, and 17.7% of the region was sub-stable, with a settling rate of −12.868 mm/yr − –6.964 mm/yr. The unstable regions included areas with settlement rates greater than 12.868 mm/yr and uplift rates greater than 10.748 mm/yr, representing 4.4 percent and 0.9 percent of the total area, respectively, for a total of 5.3 percent. The results of this paper can be used as the theoretical basis and as basic data for decision making and scientific research in various departments, and they are of great significance for surface stability assessment and early warnings along engineering corridors and traffic projects. [ABSTRACT FROM AUTHOR]

Traffic flow prediction plays an important role in intelligent transportation systems and is of great significance in the applications of traffic control and urban planning. Due to the complexity of road traffic flow data, traffic flow prediction has been one of the challenging tasks to fully exploit the spatiotemporal characteristics of roads to improve prediction accuracy. In this study, a combined flow direction level traffic flow prediction graph convolutional network (GCN) and long short-term memory (LSTM) model based on spatiotemporal characteristics is proposed. First, a GCN model is employed to capture the topological structure of the data graph and extract the spatial features of road networks. Additionally, due to the capability to handle long-term dependencies, the longterm memory is used to predict the time series of traffic flow and extract the time features. The proposed model is evaluated using real-world data, which are obtained from the intersection of Liuquan Road and Zhongrun Avenue in the Zibo High-Tech Zone of China. The results show that the developed combined GCNLSTM flow direction level traffic flow prediction model can perform better than the single models of the LSTM model and GCN model, and the combined ARIMA- LSTM model in traffic flow has a strong spatiotemporal correlation. [ABSTRACT FROM AUTHOR]

The rapid global spread of the coronavirus disease 2019 (COVID-19) is now a reality. China has taken urban traffic control measures to prevent and control the epidemic, but this has prevented the flow of people between cities. This study investigates the mechanism of the impact of urban traffic control measures on the intercity population flow in China using the one-way causal measurement method. The results show that the impact of urban traffic control measures on the intercity flow of the population changes with time. Based on this, this study makes scientific suggestions for the government on how to reasonably undertake traffic control measures. [ABSTRACT FROM AUTHOR]

With the spread of the COVID-19 pandemic and the implementation of closure measures in 2020, population mobility and human activities have decreased, which has seriously impacted atmospheric quality. Huaibei City is an important coal and chemical production base in East China, which faces increasing environmental problems. The impact of anthropogenic activities on air quality in this area was investigated by comparing the COVID-19 lockdown in 2020 with the normal situation in 2021. Tropospheric NO2, HCHO and SO2 column densities were observed by ground-based multiple axis differential optical absorption spectroscopy (MAX-DOAS). In situ measurements for PM2.5, NO2, SO2 and O3 were also taken. The observation period was divided into four phases, the pre-lockdown period, phase 1 lockdown, phase 2 lockdown and the post-lockdown period. Ground-based MAX-DOAS results showed that tropospheric NO2, HCHO and SO2 column densities increased by 41, 14 and 14%, respectively, during phase 1 in 2021 vs. 2020. In situ results showed that NO2 and SO2 increased by 59 and 11%, respectively, during phase 1 in 2021 vs. 2020, but PM2.5 and O3 decreased by 15 and 17%, respectively. In the phase 2 period, due to the partial lifting of control measures, the concentration of pollutants did not significantly change. The weekly MAX-DOAS results showed that there was no obvious weekend effect of pollutants in the Huaibei area, and NO2, HCHO and SO2 had obvious diurnal variation characteristics. In addition, the relationship between the column densities and wind speed and direction in 2020 and 2021 was studied. The results showed that, in the absence of traffic control in 2021, elevated sources in the Eastern part of the city emitted large amounts of NO2. The observed ratios of HCHO to NO2 suggested that tropospheric ozone production involved NOX-limited scenarios. The correlation analysis between HCHO and different gases showed that HCHO mainly originated from primary emission sources related to SO2. [ABSTRACT FROM AUTHOR]

Microscopic traffic flow models enable predictions of traffic operations, which allows traffic engineers to assess the efficiency and safety effects of roadway designs. Modeling vehicle trajectories inside intersections is challenging because there is an infinite number of possible paths in a two-dimensional space, and drivers can simultaneously adapt their speeds as well. To date, human driver models for simultaneous longitudinal and lateral vehicle control based on the infrastructure characteristics and interactions with other drivers inside an intersection are still lacking. The contribution of this paper is threefold. First, it proposes an integrated microscopic traffic flow model to describe human-driven vehicle maneuvers under interactions. Drivers plan their heading and acceleration in the predicted future to minimize costs representing undesirable situations. The model works with a joint optimization for an interaction cost term. The weights associated with the interaction cost reflect how selfish or altruistic drivers are. Second, the proposed model endogenously gives the order of vehicles in case of crossing paths. Third, the paper develops a clustered validation method for microscopic traffic flow models with interacting vehicles, which account for interdriver variations. Results show that the model can accurately describe vehicle passing orders of interacting maneuvers, paths, and speeds against empirical data. The model can be applied to assess various intersection designs. Funding: This work was supported by the National Natural Science Foundation of China [Grants 71971140 and 52122215] and the Natural Science Foundation of Shanghai [Grant 20ZR1439300]. [ABSTRACT FROM AUTHOR]

With the development of aviation industry, a series of problems have appeared in aviation and airspace, among which the most prominent problem is the congestion of aviation and airspace. Airspace congestion has become a major problem in the development of civil aviation in China. Especially in the central and eastern regions of China, airspace congestion is becoming more and more serious. To better solve the problem of airspace congestion, rough set theory and the Fuzzy C-means (FCM) model are first analyzed. By analyzing the temporal and spatial characteristics of traffic congestion in the control sector, a multisector traffic congestion identification model is established based on radar track data. Four multisector congestion characteristics including equivalent traffic volume, proximity, saturation, and traffic density are established. FCM and rough set theory are used to classify and identify sector congestion. Finally, the model based on FCM-rough set theory is compared with other methods based on the data of the regional control sector in northwest China. The experimental results show that the congestion recognition rate of the model is 92.6%, 93.5%, and 94.2%, and the congestion misjudgment rate is 1.5%, 1.2%, and 1.3%, respectively. Hence, the multisector congestion recognition model has a high recognition rate and a low misjudgment rate, and the overall discrimination result is relatively stable. By comparing the proposed method with other methods, it is concluded that the recognition accuracy of the model based on FCM theory is superior to other methods. In summary, the congestion situation of the sector is affected by a variety of macro- and micro-characteristics of the sector, and the congestion identification model is feasible and efficient. Multisector traffic congestion identification has certain application value for airspace planning, air traffic control-assisted decision making, and air traffic flow management. This work can optimize the aviation and airspace management system and provide relevant suggestions for the study of aviation and airspace congestion. [ABSTRACT FROM AUTHOR]

With China's fast expansion of urban traffic and railway engineering, a great number of subway and railway lines have been erected in subterranean tunnels in recent years. When the tunnel is in the process of construction, it will encounter the weak fracture zone, and the surrounding rock of this part of the tunnel is often poor stability and deformation is difficult to control, which will lead to the smooth progress of the project, delay and other problems. Therefore, to facilitate the timely treatment of tunnel soft surrounding rock, the study of image recognition of its stability is particularly important. Based on this, an improved local binary mode algorithm (ILBP) is proposed in this paper. By adjusting the weight of binary polynomial in local binary mode (LBP) operator, the target of ILBP is to extract the characteristics of weak surrounding rock of tunnel at a specific location, hoping to provide reference for the follow-up study of tunnel engineering. [ABSTRACT FROM AUTHOR]

In recent years, urban traffic congestion has seriously affected the healthy development of urbanization in China. And many measures to combat congestion have had little effect. The purpose of this paper is to find out the most reasonable and sustainable measures to control traffic congestion. Based on the theory of system dynamics, this study constructs a model of the formation mechanism of urban traffic congestion in China, and analyzes the thinking error of the traditional strategy of "building roads to eliminate traffic congestion" This study includes the current policy measures to control traffic congestion in the system dynamics model and analyzes the influence of each measure on the formation mechanism of urban traffic congestion. Then, it critiques the unsustainability of rigid policies, such as the vehicle number limit and the "similar road building to control traffic congestion" policies. This study reveals that of the five policies adopted by the government to alleviate traffic congestion, and come to the conclusion: the "sparse block collocation" policy is the most sustainable and fundamental congestion control measure. To achieve efficient traffic congestion control and support the healthy development of urbanization in China in the future, the government should increase the balance of infrastructure investment to improve the slow environment of public transport, adhere to public transport-oriented land development policies, raise the cost of motor vehicle travel, and promote urban traffic. [ABSTRACT FROM AUTHOR]

Background: With increasing urbanization in developing countries, sanitation workers are frequently involved in road traffic collisions. Our purpose was to study specific collisions involving sanitation workers and provide decision-making suggestions and reference measures for the sanitation industry and urban managers to reduce the occurrence of collisions.Methods: We obtained online news data about sanitation worker road traffic collisions in China between 2013 and 2017 and analyzed occurrence time and location, victim characteristics, and causes of collisions.Results: In China, between 2013 and 2017, 511 road traffic collisions were reported, with the fewest in February and July. Most occurred around 5:00 a.m. in Eastern regions and in urban areas. Victims were mainly over 50 years old, with more females than males. Collisions usually resulted in death at the scene. The ambiguity of laws, the exploitation of workers through industry outsourcing, and the difficulty of processing claims may be the main factors preventing victims from obtaining legal compensation.Conclusions: The most common cause of collisions was drivers' speeding, but workers also regularly risk death by crossing the road in pursuit of their duties. The absence of legal controls for environmental protection, the excessive pursuit of efficiency in urban governance, and the lack of basic education of sanitation workers are underlying causes of collisions. Raising awareness about sanitation worker road traffic collisions will help protect the work safety rights of this vulnerable group. [ABSTRACT FROM AUTHOR]

This article analyses the effectiveness of the Chinese road traffic liability system in terms of both deterrence and compensation. We utilize the neo-classical economic model of accidents to assess the key features of the system, such as the basis of liability, the level of the benefits, the impacts of liability insurance and regulation, as well as the capacity of riskspreading. The analysis shows that the road traffic liability system in China can only achieve partial deterrence. Undercompensation and insufficient risk-spreading seem to be serious problems, at least in the economically underdeveloped regions. Therefore, we propose several legislative changes that the policymaker could implement to improve the system. [ABSTRACT FROM AUTHOR]

With the improvement of our country's economic level and quality of life, the numbers and scales of highway networks and motor vehicles are constantly expanding, which makes the current road traffic burden more and more serious. As an important means of traffic automation management, license plate recognition (LPR) technology plays an important role in traffic surveillance and control. However, the recognition rate and accuracy of the traditional license plate recognition methods still need to be improved. In the case of poor surrounding environment, it is prone to localization failure, vehicle license plate recognition errors or unrecognizable phenomena. Wavelet transform, as another landmark signal processing method after Fourier transform, has been widely used in the field of image processing. In China, the number of horizontal lines is usually larger than that of vertical lines. If the two vertical boundaries of the license plate can be detected successfully, the four angles of the license plate can be determined efficiently to complete the license plate positioning. In view of the advantages of wavelet transform technology and the characteristics of vehicle license plate, in this paper, a vehicle license plate recognition algorithm based on wavelet transform and vertical edge matching is proposed. The edge of the license plate is detected by wavelet transform technology, and then the license plate is located by vertical edge matching technology. After the location is realized, the characters are segmented by vertical projection method and the characters are recognized by improved BP neural network algorithm. The experimental results show that the proposed vehicle license plate recognition algorithm based on wavelet transform and vertical edge matching performs well in algorithm performance, which provides a good reference for the development of vehicle license plate recognition system. [ABSTRACT FROM AUTHOR]

Fatigue fractures can be frequently observed in welded joints in orthotropic steel decks (OSDs) after just a few decades of operation, which become the major deterioration mechanism deterring the serviceability of OSDs. In this paper, a novel dynamic Bayesian network (DBN) model has been established for the fatigue reliability analysis of OSDs at system-level. The exact inference algorithm is applied in the DBN model with discrete variables. Special modifications have been made on the existing algorithm to improve the computational efficiency in dealing with the deck system consisting of a considerable number of joints. Using the DBN model, the fatigue reliability of welded joints can be predicted and updated with the inspection and monitoring results at system-level. At the same time, a framework is established for the system-level reliability considering the fatigue fracture of rib-to-deck (RD) joints, the dominant cracking pattern affecting the serviceability of OSDs. For illustration, a typical OSD bridge in China has been selected to carry out a case study. To derive the stress spectrum required by the DBN model, the stochastic traffic model is employed, and the influence-based Monte Carlo simulations have been carried out. As a result, the fatigue reliability can be predicted at both component- and system-levels. Meanwhile, the observation of the traffic and the inspection result has been fused into the DBN model to update the deteriorating state of the deck system. Besides, the effect of enhancement and maintenance has been highlighted, including the enhancement in fatigue strength at the construction stage, and the repair and traffic control during the operation stage. • A novel dynamic Bayesian network (DBN) model is established for the fatigue reliability of orthotropic steel decks (OSDs). • Special modifications are made on the inference algorithm of the DBN model to improve computational efficiency. • A framework is established for the system-level fatigue reliability of OSDs based on serviceability. • The DBN model is illustrated with a case study, including prediction, information-based fusion and evidence-based updating. • The effects of enhancement and maintenance are investigated using the DBN model. [ABSTRACT FROM AUTHOR]

Due to the inappropriate path caused by traffic control, climatic conditions, and inconsistent regional economic development, etc., the transportation efficiency of emergency relief supplies is low in mining areas in China. To improve the transportation efficiency, a road impedance function model was proposed based on the uniqueness of emergency relief supplies' transportation after mine disasters. The model, which aimed to solve the optimal transport time conforming to practical traffic conditions, was designed in accordance with China's road design norms and actual traffic flows while considering random delays at road junctions. The weight of path was calculated from the road impedance function model and traffic allocation simulation data. The feasibility and universality of the model were proved by performing simulations under normal traffic, rainfall and traffic control conditions. Results indicate that the optimal path selection by the Dijkstra algorithm achieves a high accuracy. Time cost under rainfall and traffic control conditions increases by 3.3 % and 1 %, respectively, compared with the normal condition. This study provides new ideas to select transport path for emergency relief supplies. [ABSTRACT FROM AUTHOR]

Rolling stock connections and route conflicts of trains at terminal stations are critical to train delay propagation and prediction on the railway networks. Previous studies primarily focused on delay prediction/propagation from a macro perspective, without considering the two factors. To address this problem, a hybrid neural network architecture, called TLF-net, is proposed to predict departure delays at original stations (DDOSs), considering the rolling-stock connection and potential route conflicts in the railway network. TLF-net consists of a transformer, a long short-term memory (LSTM), and a fully-connected neural network (FCNN) block, to separately address variables with different characteristics. Based on the real-world data from two terminal stations in China, the experimental results show that the consideration of the potential route conflicts from the network can considerably improve TLF-net's prediction performance over the model that only considers train interactions on a single railway line. Also, it is proven that arrival/departure routes of consecutive trains are crucial for delay prediction, while using the transformer block can efficiently reveal the route conflict severity between arrival/departure routes. The sensitivity analysis to influence factors demonstrates the significance of considering the rolling stock connection and potential route conflicts. Finally, to support real-time railway traffic management, a train arrival delay prediction model from our previous study is integrated to predict the input of TLF-net (i.e., train arrival delays), enabling the proposed model to dynamically predict the DDOSs. This dynamic updating lengthens the prediction horizon (the prediction time ahead), making it better support real-time train traffic control and management. [ABSTRACT FROM AUTHOR]

Two-stop-line signalized roundabouts (TSLSR) are widely utilized in China. To calculate the capacity and optimal cycle length accurately, a model considering internal space constraint of the roundabout is developed in this paper. Firstly, the operational principle of TSLSR is analyzed. TSLSR is modeled as being equivalent to a four-phase intersection with left-turn protection phases, and the left-turn lane is further simplified as the "short-lane model". Secondly, based on the above analysis, the capacity of TSLSR is modeled and additionally, the accuracy and sensitivity of the model are also analyzed. Finally, the optimal cycle length of TSLSR which maximizes the capacity is put forward. Results show that the accuracy of the capacity model is low without considering the internal space constraint of the roundabout. However, the model developed in this paper is shown to improve the accuracy (about 20%) and control the relative error to be within 10%. The parameter sensitivity analysis demonstrates that the cycle length and radius of the central island have a significant influence on the capacity of the left-turn lane and results in an optimal value of signal cycle length maximizing the capacity. [ABSTRACT FROM AUTHOR]

China's rapid urbanization and high traffic accident frequency have received many researchers’ attention. It is important to reveal how urban infrastructures and other risk factors affects the traffic accident frequency. A growing amount of research has examined the local risk factors impact on traffic accident frequency at certain time. Some studies considered these spatial influences but overlooked the temporal correlation/heterogeneity of traffic accidents and related risk factors. This study explores risk factors’ influence on urban traffic accidents frequency while considering both the spatial and temporal correlation/heterogeneity of traffic accidents. The study area is split into 100 equally sized rectangle traffic analysis zones (TAZs), and the urban traffic accident frequency and attributes in each TAZ are extracted. The linear regression model, spatial lag model (SLM), spatial error model (SEM) and time-fixed effects error model (T-FEEM) are established and compared respectively. The proposed methodologies are illustrated using ten-month traffic accident data from the urban area of Guiyang City, China. The results reveal that the time-fixed effects error model, which considers both spatial and temporal correlation/heterogeneity of traffic accidents, is superior to other models. More traffic accidents will happen in those TAZs that have more hospitals or schools. Moreover, hospitals have a greater influence on traffic accidents than schools. Because of the location in the margin of the city, those TAZs that have passenger stations have more traffic accidents. This study provides policy makers with more detailed characterization about the impact of related risk factors on traffic accident frequencies, and it is suggested that not only the spatial correlation/heterogeneity but also the temporal correlation/heterogeneity should be taken into account in guiding traffic accident control of urban area. [ABSTRACT FROM AUTHOR]

Efficiency and equity have always been the two points of focus of transport projects. Compared with efficiency, equity is easily overlooked in the evaluation of transport projects. Many studies emphasize that defining and operationalizing costs and benefits and the distributive principle are critical parts in the assessment of transportation equity. However, the scope and time frame of the assessment target are also critical. In this paper, we took China’s fastest urbanizing city, Shenzhen, as a case study to assess transport equity by comparing accessibility among groups. First, the public transport system was divided into bus and subway, and the residents were divided into two groups: urban village and nonurban village. Second, we adopted an enhanced potential opportunity model to measure residents’ bus and subway accessibility and summarized them as transit opportunity. Third, we used the Dagum Gini coefficient decomposition and kernel density estimation method to explore the fair distribution of transit opportunity among groups and districts from 2011 to 2020. Decade-long changes in disparity and distribution of transit opportunity gave us a clear picture. On the one hand, the development of Shenzhen public transport system had a positive effect. All populations are benefiting, and their accessibility is increasing. On the other hand, it also had a negative effect to exacerbate inequality between populations. For the absolute value of the opportunity, Shenzhen’s urban village populations do have fewer transportation opportunities than nonurban villages, and this gap between them will be wider more and more. The public transport system is more inclined to improve the population with high initial opportunity and make them higher. The results illustrated the importance of examining transportation equity over an extended period and could provide information on urban development strategies. [ABSTRACT FROM AUTHOR]

Merging behavior is inevitable at on-ramp bottlenecks and is a significant factor in triggering traffic breakdown. In modeling merging behaviors, the gap acceptance theory is generally used. Gap acceptance theory holds that when a gap is larger than the critical gap, the vehicle will merge into the mainline. In this study, however, analyses not only focus on the accepted gaps, but also take the rejected gaps into account, and the impact on merging behavior with multi-rejected (more than once rejecting behavior) gaps was investigated; it shows that the multi-rejected gaps have a great influence on the estimation of critical gap and merging prediction. Two empirical trajectory data sets were collected and analyzed: one at Yan’an Expressway in Shanghai, China, and the other at Highway 101 in Los Angeles, USA. The study made three main contributions. First, it gives the quantitative measurement of the rejected gap which is also a detailed description of non-merging event and investigated the characteristics of the multi-rejected gaps; second, taking the multi-rejected gaps into consideration, it further expanded the concept of the “critical gap” which can be a statistic one and the distribution function of merging probability with respect to such gaps was analyzed by means of survival analysis. This way could make the full use of multi-rejected gaps and accepted gaps and reduce the sample bias, thus estimating the critical gap accurately; finally, considering multi-rejected gaps, it created logistic regression models to predict merging behavior. These models were tested using field data, and satisfactory performances were obtained. [ABSTRACT FROM AUTHOR]

Exploring travel time distribution and variability patterns is essential for reliable route choices and sophisticated traffic management and control. State-of-the-art studies tend to treat different types of roads equally, which fails to provide more detailed analysis of travel time characteristics for each specific road type. In this study, based on a vast amount of probe vehicle data, 200 links inside the Third Ring Road of Beijing, China, were investigated. Four types of roads were covered including urban expressways, auxiliary roads of urban expressways, major roads, and secondary roads. The day-of-week distributions of unit distance travel time were first analyzed. Kolmogorov-Smirnov test, Anderson-Darling test, and chi-squared test were employed to test the goodness-of-fit of different distributions and the results showed lognormal distribution was best-fitted for different time periods and road types compared with normal, gamma, and Weibull distribution. In addition, four reliability measures, that is, unit distance travel time, coefficient of variation, buffer time index, and punctuality rate, were used to explore the day-of-week travel time variability patterns. The results indicated that urban expressways, auxiliary roads of urban expressways, and major roads have regular and distinct morning and afternoon peaks on weekdays. It is noteworthy that in daytime the travel times on auxiliary roads of urban expressways and major roads share similar variability patterns and appear relatively stable and reliable, while urban expressways have most reliable travel times at night. The results of analysis help enable a better understanding of the volatile travel time characteristics of each road type in urban network. [ABSTRACT FROM AUTHOR]

Station inflow control (SIC) is an important and effective method for reducing recurrent congestion during peak hours in the Beijing, Shanghai, and Guangzhou subway systems. This work proposes a practical and efficient method for establishing a static SIC scheme in normal weekdays for large-scale subway networks. First, a traffic assignment model without capacity constraint is utilized to determine passenger flow distributions on the network. An internal relationship between station inflows and section flows is then constructed. Second, capacity bottlenecks are identified by considering the transport capacity of each section. Then, a feedback-based bottleneck elimination strategy is established to search target control stations and determine their control time and control strength. To validate the effectiveness of the proposed approach, a decision support system coded in the C# programming language was developed, and the Beijing subway was used as a case study. The results indicate that the proposed method and tool are capable of practical applications, and the generated SIC plan has better performance over the existing SIC plan. This study provides a practical and useful method for operation agencies to construct SIC schemes in the subway system. [ABSTRACT FROM AUTHOR]

Introduction: Road traffic can play an important role in strengthening regional economic activities, especially at high altitude, and it is necessary to know important traffic-related information. Although previous studies reported on road traffic in China, there has been little research on high-altitude road traffic to date. Method: The annual official census of road traffic safety from 2006 to 2013 was used to obtain data on the general population, registered drivers, registered vehicles, newly built roads, road traffic accidents (RTAs), mortality rate per 100 000 populations and per 10 000 vehicles in high-altitude provinces, including Tibet, Qinghai, Xinjiang, Gansu, Yunnan, Sichuan, and Chongqing. These provincial data were reviewed retrospectively, with the national data as the reference. Statistical analysis (i.e., t test) was used to compare the estimated average annual change rate of population, number of registered drivers, registered vehicles, and newly built roads in high-altitude provinces with the national rates. Results: Compared with the national data, there are significantly higher annual rates of population growth in Tibet and Xinjiang, registered drivers in Gansu, registered vehicles in Gansu, Sichuan, and Chongqing, and newly built roads in Tibet and Qinghai. Among the investigated provinces, Tibet, Qinghai, and Yunnan had a higher proportion of the roads with the high class. RTAs and RTA-induced casualties in the high-altitude provinces indicated a decreasing trend. The mortality rate per 10 000 vehicles and per 100 000 populations showed a decreasing trend, while the RTA-related mortality rate in Tibet, Qinghai, Xinjiang and Gansu remained high. Conclusions: Major changes for road traffic in high-altitude provinces have occurred over the past decade; however, the RTA-related mortality rate in high-altitude provinces has remained high. This study furthers understanding about road traffic safety in China; further studies on road traffic safety at high altitude should be performed. [ABSTRACT FROM AUTHOR]

Advanced decision support for rail traffic control is significant for enhancing the safety and quality of railway transport service. Data-driven methods have shown powerful learning ability and wide extensibility for prediction, classification, and decision-making problems. In this paper, we propose a hybrid prediction model based on deep forest (DF) ensemble learning to analyze the two common rail traffic control actions, i.e., changing the dwelling times and running times. This basic concept is to mimic the decision-making of rail traffic controllers, providing them with advanced decisions/control actions using data-driven learning algorithms. According to the decision-making approach of rail traffic controllers, the learning process of the model is split into two stages, i.e., learning the type of action (ToA) and the number of changes (NoC) in the dwelling times and running times (i.e., how many dwelling times or running times have been changed compared with the planned ones). The first stage is a classification problem; thus, DF classifier with the synthetic minority oversampling technique (SMOTE) is employed to deal with imbalanced data. In the second stage, the DF regressor treats the NoC in the dwelling and running times as numerical variables and utilizes the information from stage one, i.e., the prediction results of the classification model, to make predictions. The proposed model is calibrated on train operation data from two high-speed railway lines in China. The experimental results and comparative analyses show that the proposed method provides advanced and timely decision support for controllers. These characteristics of the proposed model are imperative for supporting the dynamic decision-making of controllers to manage railway traffic. [ABSTRACT FROM AUTHOR]

Objectives: Road traffic crashes that involve very high numbers of fatalities and injuries arouse public concern wherever they occur. In China, there are two categories of such crashes: a crash that results in 10–30 fatalities, 50–100 serious injuries or a total cost of 50–100 million RMB ($US8-16m) is a “serious road traffic crash” (SRTC), while a crash that is even more severe or costly is a “particularly serious road traffic crash” (PSRTC). The aim of this study is to identify the main factors affecting different types of these crashes (single-vehicle, head-on, rear-end and side impact) with the ultimate goal of informing prevention activities and policies. Methods: Detailed descriptions of the SRTCs and PSRTCs that occurred from 2007 to 2014 were collected from the database “In-depth Investigation and Analysis System for Major Road Traffic Crashes” (IIASMRTC), which is maintained by the Traffic Management Research Institute of the Ministry of Public Security of China (TMRI). 18 main risk factors, which were categorized into four areas (participant, vehicle, road and environment-related) were chosen as potential independent variables for the multinomial logistic regression analysis. Comparisons were made among the single-vehicle, head-on, rear-end and side impact crashes in terms of factors affecting crash occurrence. Findings: Five risk factors were significant for the six multinomial logistic regression models, which were location, vertical alignment, roadside safety rating, driver distraction and overloading of cargo. It was indicated that intersections were more likely to have side impact SRTCs and PSRTCs, especially with poor visibility at night. Overloaded freight vehicles were more likely to be involved in a rear-end crash than other freight vehicles. Driver distraction is an important risk factor for head-on crashes, while vertical alignment and roadside safety rating are positively associated with single-vehicle crashes. Conclusion: Based on the findings, promising measures were proposed to prevent each type of SRTC and PSRTC, which governmental or regulatory agencies could employ to plan strategies to reduce SRTCs and PSRTCs and support lifesaving policies. [ABSTRACT FROM AUTHOR]

Lower standard rural roads with a design speed less than 40 km/h account for more than 80% of total roadway network in China. In most situations, vehicles on these rural roads are of free traffic flow, and the driving stability of a vehicle is therefore mostly influenced by alignments and road surface. Single-vehicle run-off-road crashes are often associated with poor road conditions. Therefore, the improvement of alignment design of the roads can be effective to reduce the number of traffic accidents. This research targets at the analysis of driving in several sections of a four-class rural road in Yunan province, China, with varying alignments and complex shapes. In this context, a road creation module, a vehicle dynamics model, and driver module are established in computing environment, and integrated into a “roadway-driver-vehicle” virtual driving system. Driving simulations of a passenger car model on the test segments are conducted. Speed, driver workload, and ride comfort are analyzed in relation to varying geometric alignments. The simulation results show that: by balancing the design parameters of adjacent curve radii and the tangent length in-between, critical safety driving speed on lower standard rural roads can be obtained; the use of hairpin curves and the absence of spirals would lead to a rapid increase in both angular speed of steering wheel and lateral acceleration change rate, resulting in increasing driver nervousness and passenger discomfort. [ABSTRACT FROM AUTHOR]

On the basis of summarizing and analyzing the relevant researches in China and foreign countries, this paper carries out the study on comprehensive evaluation index system of low carbon road transport which mainly adopts the Fuzzy Evaluation method with Analytic Hierarchy Process and Delphi. The factors of low carbon road transport are divided into three categories, including road infrastructure, road traffic, road management and related policies and regulations, in which the factors that have an important impact on low carbon road transport development are chosen and analyzed. And then the chosen factors turn into the evaluation index, through the judgment matrix, fuzzy weight vector of each index is calculated and examined by the consistency test. Finally, index coefficients of each layer are obtained. In the case study part, we found out that the low carbon traffic structure development of Shanghai road network is 0.5478, which is between “good” and “general”. [ABSTRACT FROM AUTHOR]

When railway emergency lead to traffic interruption for some sections, it is indispensable for railway administration to take some urgent processing measures for transporting detained passengers and trains. This paper focuses on the method of generating train paths in traffic interruption conditions and proposed the idea that signal system compatibility is a considerable factor in the procedure of searching paths. On the basis of this idea, it was designed that the algorithm of generating train path in terms of adequate capacity strategy. The core of the algorithm is recursive dijkstra algorithm. Finally, we confirmed the practicability of algorithm through an example. The result showed that the proposed algorithm for generating train feasible paths provides references to the organization of railway traffic organization in traffic interruption conditions. [ABSTRACT FROM AUTHOR]

Three different type of double road trains are selected as simulation model, which is commonly used in developed countries and regions in order to improve the efficiency of road transport and the development of China's logistics industry. The passing ability simulation model of double road train is established based on Auto Turn, and China's current longest tractor-semitrailer is used as a comparison. Simulation models of highway ramp, first class highway and second class highway are established according to the requirement of JTG D20-2006 ‘Design Specification for Highway Alignment’. Adaptability of double road train and highway structure parameter is researched by analyzing different types of double road train turn left, turn right and turn around on the road. The type of double road train which can meet China's standards is recommended. The result can promote the application of double road train and give some advice for improving passing ability. [ABSTRACT FROM AUTHOR]

The objective of this research is to develop a dynamic model to predict bus dwell time at downstream stops. The research also intends to test the proposed model using real-world data. This model is based on k-Nearest Neighbour (KNN) algorithm using history and current data collected by GPS (Global Positon System) fixed on buses. In the research, the data of buses of No.B1 line of Changzhou in China is used. In the test with real-world data, the proposed bus dwell time prediction model performed effectively both on accuracy and calculating speed. [ABSTRACT FROM AUTHOR]

With the rapid economic growth in China, the road transportation system was becoming one of the largest and most rapidly growing oil consumers in China. This paper focused on the current status and development trend of energy efficiency and CO 2 emission intensity of commercial trucks. According to the statistical data of commercial trucks from China's Ministry of Transport, there were 10% ∼ 30% differences about the energy efficiency and CO 2 emission intensity among different brands of trucks under the same mass section in the industry standard (JT719-2008). There have appeared a group of vehicle with low emission and high energy efficiency. Energy efficiency standards and energy efficiency label system have been proven to promote energy-saving technology progress. In order to promote the development of energy efficiency and CO 2 emission intensity of commercial trucks, the ‘Top Runner’ method was proposed to classify the energy efficiency and CO 2 emission intensity of commercial trucks by coincidence rate, which would lead the road transportation enterprises to high energy efficiency trucks. [ABSTRACT FROM AUTHOR]

The freeway plays an essential role in intercity transportation, due to its safety, convenience and efficiency. To ensure the gradually networked freeway system to operate smoothly and efficiently, the connective reliability evaluation become extremely important. Applying the complex network approach, the improved evaluation indicators of complex network, such as structural degree, betweenness and shortest path length are defined respectively to reflect the freeway network's structural properties firstly. Secondly, a measurement considering the effective paths number is proposed to evaluate freeway network's connective reliability. Finally, based on the freeway network in Shandong Province (SFN), which is the largest scale freeway network in eastern China, those evaluation indicators are calculated, and the freeway network's connective reliability are evaluated under different scenarios. The nodes with high structural betweenness must be given more protection so as to improve the reliability of the SFN under random attack The structural properties and reliability analysis of freeway networks are helpful for road planning and unexpected major events control. [ABSTRACT FROM AUTHOR]

Transportation is an important safeguard for the running and development of a city. While, on the one hand, contribute to the soar and scale expansion of urban economy, urban transportation dominated by small vehicles, on the other hand, triggered various urban problems with respect to congestion, energy consumption and environment protection. Although demand-driven transportation development strategy has proved to effectively relieve congestion problems in urban transportation for a certain period of time, such strategy also led to an even swift inflation of traffic demand and thus it is not a thorough solution to the problem of supply and demand imbalance in urban transportation. Therefore, policies concerning the management of the demand of urban transportation represented by congestion charging policy gradually enter into the sight of decision makers of urban transportation and become an effective measure for first-tier cities in China to relieve congestion and improve air quality. [ABSTRACT FROM AUTHOR]

PM 2.5 with its major chemical components were measured and analyzed during a concurrent haze in Jan. 1–19, 2013 at three sites (Shanghai, Beijing, and Huaniao, a remote isle over the East China Sea) to probe the sources and formation process of such a severe haze over three typical regions in China. The mean PM 2.5 concentrations during the severely polluted days reached 180.8 μg m −3 , 299.2 μg m −3 , and 131.1 μg m −3 in Shanghai, Beijing, and the Huaniao Isle, respectively. The mass ratio of the sum of SO 4 2 − , NO 3 − , and NH 4 + to PM 2.5 were over 1/3 during the polluted days at all the three sites. Promoted gas-to-particle transformations from acidic SO 2 and NO x to SO 4 2 − and NO 3 − under high relative humidity conditions played a major role in the formation of this severe haze. Significant contribution of traffic emissions to the haze formation over China was suggested to be one of the major sources in triggering the heavy haze over China. Specifically, there was a more contribution from traffic in Shanghai than in Beijing as indicated by the higher NO 3 − / SO 4 2− ratio in Shanghai. In Beijing, the enhanced coal combustion for winter heating along with the traffic emission was suggested to be the major two sources of this haze episode. Typical pollution elements such as As, Cd, and Pb as well as Cl − and K + were substantially enhanced in the severely polluted days. Although the Huaniao Isle is located in the remote oceanic area as a background site, pollution elements, secondary ions, and K + all increased substantially during the polluted days. As visualized by the backward air mass trajectories associated with the potential source region identification technique, air masses that passed over Northern China and Yangtze River Delta evidently invaded the offshore areas of Eastern China. The ratios of As, Cd, Cu, Zn, and K + to Al at the Huaniao Isle were closer to those of Beijing rather than Shanghai, indicating that the marine aerosol over the East China Sea had been significantly polluted via the long-range transport of anthropogenic pollutants originating from Northern China. [ABSTRACT FROM AUTHOR]

This study aimed to calibrate saturation flow rate (SFR) and start-up lost time (SLT) when developing signal timing. In current commonly used methods, SFR for one given lane is usually calibrated from many subjective adjustment factors and a fixed result. SLT is calculated based on the fixed SFR, which prevents local applications in China. Considering the importance of traffic behavior (headway) in determining SFR and SLT, this study started from headway distribution and attempted to specify the relationships between headway and vehicle position directly. A common intersection in Nanjing, China, was selected to implement field study and data from 920 queues was collected. Headway distribution was explored and the 78th percentile of headway at each position was selected to build model. Based on the developed relationships, SFR and SLT were calibrated. The results showed that SFR and SLT were correlated with queue length. Moreover, the results showed that it was difficult to reach saturated state even with a long queue length. This paper provides a new perspective on calibrating important parameters in signal timing, which will be useful for traffic agencies to complete signal timing by making the process simpler. [ABSTRACT FROM AUTHOR]

This paper aims to examine characteristics of e-bike fatal crashes on urban highways in China. Crash data were retrieved from the three-year crash reports (2010–2012) of Taixing City. Descriptive analysis was conducted to examine characteristics of e-bike riders, drivers, and crashes. The important findings include the following: (1) most fatal crashes were related to e-bike riders’ aberrant driving behaviors, including driving in motorized lanes, red-light running, driving against the direction of traffic, inattentive driving, and drunk driving; (2) e-bike riders with lower educational background tended to perform illegal or inattentive driving behaviors in fatal crashes; (3) most drivers were not found to commit any faults and very few drivers were found to commit drunk driving offences; (4) most nighttime fatal crashes were related to absence of street lightings; (5) heavy good vehicles (HGVs) and small passenger cars were the two vehicle types that were mostly involved in the e-bike fatal crashes. This study provides useful information that can help traffic engineers better understand e-bike safety in China and develop safety countermeasures. [ABSTRACT FROM AUTHOR]

This study is the first in a series of papers that aim to develop high-resolution emission databases for different anthropogenic sources in China. Here we focus on on-road transportation. Because of the increasing impact of on-road transportation on regional air quality, developing an accurate and high-resolution vehicle emission inventory is important for both the research community and air quality management. This work proposes a new inventory methodology to improve the spatial and temporal accuracy and resolution of vehicle emissions in China. We calculate, for the first time, the monthly vehicle emissions for 2008 in 2364 counties (an administrative unit one level lower than city) by developing a set of approaches to estimate vehicle stock and monthly emission factors at county-level, and technology distribution at provincial level. We then introduce allocation weights for the vehicle kilometers traveled to assign the county-level emissions onto 0.05° x 0.05° grids based on the China Digital Road-network Map (CDRM). The new methodology overcomes the common shortcomings of previous inventory methods, including neglecting the geographical differences between key parameters and using surrogates that are weakly related to vehicle activities to allocate vehicle emissions. The new method has great advantages over previous methods in depicting the spatial distribution characteristics of vehicle activities and emissions. This work provides a better understanding of the spatial representation of vehicle emissions in China and can benefit both air quality modeling and management with improved spatial accuracy. [ABSTRACT FROM AUTHOR]

As an important part of the urban Advanced Traffic Management Systems (ATMS) and Advanced Traveler Information Systems (ATIS), short-term road traffic prediction system has received special attention in recent decades. The success of ATMS and ATIS technology deployment is heavily dependent on the availability of timely and accurate estimation or prediction of prevailing and emerging traffic conditions. We studied a real-time road traffic prediction system developed for Beijing based on various traffic detection systems. The logical architecture of the system was presented, including raw data level, data processing and calculation level, and application level. Four key function servers were introduced, namely, the database server, calculation server, Geographic Information System (GIS) server, and web application server. The functions, function modules, and the data flow of the proposed traffic prediction system were analyzed, and subsequently prediction models used in this system are described. Finally, the prediction performance of the system in practice was analyzed. The application of the system in Beijing indicated that the proposed and developed system was feasible, robust, and reliable in practice. [ABSTRACT FROM AUTHOR]

The expressways in Beijing are confronted with more serious traffic congestions. Based on the survey data obtained fromthe typical sections at the expressways, the time dependent characteristics of traffic flow parameters were analyzed in detail and the data gap was found in this paper. The Fast Fourier Transform (FFT) method is proposed to transfer the data of traffic flow parameters for describing the fluctuation characteristics of traffic flow. Two methods of identification, the graph method and the control line method, were proposed as to the change time of traffic bottleneck forming and dissipating. The findings in this paper have already been applied in traffic management and ramp control at the expressways in Beijing. [ABSTRACT FROM AUTHOR]

The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the road dust loadings and to understand the chemical characteristics of PM and PM from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM and PM filter samples. The average road dust loading was 3.82 g m, with the highest of 24.22 g m being in Hutongs in the rural-urban continuum during winter. The road dust loadings on higher-grade roads were lower than those on lower-grade roads. Attention should be paid to the pollution in the rural-urban continuum areas. The sums of element abundances measured were 16.17% and 18.50% for PM and PM in road dust. The average abundances of OC and EC in PM and PM in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC in PM and PM resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing. Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl and Na was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations, and groundwater. [ABSTRACT FROM AUTHOR]

To solve the problem in pedestrian Mid-Block street crossing, the method of signal coordination control between mid-block street crossing and intersection is researched in this paper. The paper proposes to use "distance-flow rate-time" graph as the tool for building coordination control system model which is for different situations of traffic control. Through alternating the linear optimization model, the system outputs the distribution of signal timing and system operational factors delays in vehicles and mid-block street crossing. Finally, taking one section on the Taiping North Road in Nanjing as an example, the signal coordination control is carried out. And the results which are delays in the vehicles and mid-block street crossing are compared to those in the current distribution of signal timing. [ABSTRACT FROM AUTHOR]

Based on the research progress in related fields and the distribution characteristics of road networks in valley cities, the complex network model of a city road network is established to study its connectivity reliability. Taking Lanzhou as the example, several parameters of the complex network abstracted from the road network are calculated and the practical meanings of them are described, respectively. On this basis, through computing the global efficiency and the relative size of the largest connecting subgraph under intentional attacks and random attacks, respectively, the curves of the above two parameters varying with the attacking times are drawn. The detailed investigation of connectivity reliability of Lanzhou road network is done by analyzing the curves' tendency. Finally, we find that the network of a valley city has a poor connection and has a lot of dead ends. Besides, the average length of the roads is very long and the holistic connectivity reliability is at a lower level; these are suitable to the group-type distribution of valley city's road network, and the connectivity reliability of the road network is stronger under random attacks than that under intentional attacks. [ABSTRACT FROM AUTHOR]

Abstract: On 12 May 2008, the devastating magnitude 8.0 (Wenchuan, Sichuan Province) struck the Longmen Shan and neighboring region, which are located at the eastern edge of the Tibetan plateau and the western Sichuan basin in China. In the earthquake-stricken areas, road traffic facilities, especially bridge structures, were also destroyed heavily under the action of seismic waves. Because the secondary geological disaster of Wenchuan events were also serious, how to analyze damage modes of highway traffic facilities scientifically and organize rebuilding of transportation and construction of emergency road network in the earthquake-stricken areas have become an urgent topic to decisionmakers and engineers. According to geological structure and seismic features, damage modes of highway traffic facilities were analysed, and restoration and reconstruction of transportation would be characterized by its long-running works. It is concluded from the field investigations that the wrecked pavements in the seismic region are with extrusion and tenso-shear failure characteristics, and the destroyed side slopes of roadbed have the wrecking modes which collapse on the coseismic responses or damage because of the secondary geological disaster, and the destroyed bridges are characterized by abutment subsidence, piers damage, impact extrusion damage, bridge span damage and so on. In accordance with the damage modes of highway traffic facilities above, some attentive problems about the road traffic restoration and reconstruction of the earthquake-stricken areas are preliminarily discussed. [Copyright &y& Elsevier]

Abstract: Concurrent sampling of PM2.5 aerosol at a roadside of heavy traffic (1.2 m above ground) and on a nearby rooftop (50 m above ground) was conducted at a same location in urban Guangzhou in September, October 2006 and January 2007. The samples were analyzed for eighteen polycyclic aromatic hydrocarbons (PAHs), together with major aerosol constituents and certain organic tracers for vehicular emissions (hopanes) and biomass burning (levoglucosan). Elemental carbon (EC) and hopanes were observed to be lower by 21–38% and 28–84%, respectively, at the rooftop than the roadside, confirming vehicular emissions as a significant local PM source. On the other hand, sulfate showed little vertical gradient, consistent with its secondary origin and its regional characteristics. The roadside-rooftop sample pairs have provided an opportunity in evaluating relative contributions of vehicular emissions and regional sources to ambient PAHs in this urban location. Concentrations of the total PAHs were ∼43% lower at rooftop in the September 2006 samples while they were at similar levels between rooftop and roadside in the October 2006 and January 2007 samples. Sources of PAHs were investigated through comparing ambient data of PAH isomer pairs and PAH/EC ratios with relevant source profiles including those of Guangzhou roadway tunnel emissions, rice straw/sugarcane leave combustion, and industrial coal combustion. The 4-ring PAHs such as pyrene and fluoranthene had a shift in their dominating source from vehicular emissions in September and October to regional combustion source in January. A few major 5- and 6-ring PAHs such as benzo[ghi]perylene and indeno[1,2,3-cd]pyrene were likely heavily influenced by regional biomass burning emissions in all three sampling months. Benzo(a)pyrene-equivalent carcinogenic potency (BaPeq) was calculated to evaluate the cancer risk of carcinogenic PAHs on the public. BaPeq levels in PM2.5 were significantly higher at the roadside than those at the rooftop in September; however, levels of BaPeq at the rooftop were drastically elevated and became comparable to those at the roadside in October and January due to regional sources dominating the carcinogenic PAHs. This suggests that it is important to control regional combustion sources to reduce air pollution-related health risk in urban Guangzhou. [Copyright &y& Elsevier]

Abstract: With China''s urbanization construction development, urban size becomes larger and larger, and the number of urban vehicles is increasing rapidly. The contradictions rise with the keeping on huge demand road while the infrastructure is relatively insufficient. To settle down the traffic problem, technical measures should be taken. In this paper, we propose a RFID-based intelligent traffic control system. The contributions of our work is defining the RFID-based intelligent traffic control system (RITCS in short) that can ease traffic jam phenomenon, Judging crossroad''s jam caused by traffic accident and alarming automatically, informing drivers the traffic jams situation direction of forward motion by notice board, and changing the signals to control the traffic volume dynamically to ease the traffic pressure. The algorithm proposed in the paper descript how the traffic accident being judged, how the signals are changed and what message about the traffic situation being showed on the notice board. The experiment result shows that the algorithm can help improving the crossroads’ traffic volume and easing the traffic jam to the best. [Copyright &y& Elsevier]

Abstract: Environmental impact evaluation is an essential component in environmental impact assessment study for any developmental project. In China, the rapid development of local and regional transportation systems has been accompanied by environmental problems, which prove to be detrimental for the economic development, social stability and public health. The project METRASYS provide a prototype for an integrated environmental monitoring and simulation system. This project deals with one of the most exigent problems of current and future mega cities and metropolitan regions. Under a scenario, various case studies of environmental impacts caused by transport in urban areas have been studied using the REGOZON model. This model includes a built-in mesoscale meteorological model that computes the local meteorological fields from synoptic fields. Since the emission model strongly depends on the other submodels, the whole system architecture for traffic flow, traffic emissions and air pollution dispersion will also be introduced. This paper describes the methodology used to evaluate these impacts. Data bases for model input and simulation results, as well as a graphic user interface for spatial data visualization. Some of the results are presented here in this paper, in particular a scenario analysis for the region Hefei. [Copyright &y& Elsevier]

Many studies focused on the analysis of effect factors contributing to the crashes and development of crash prediction models have resulted in aggregate researches to quantify the safety effects of geometric and traffic variables and environmental concerns on the expected outcome of fatal, injury and/or property damage losses at specific locations. Crash insight regarding different locations, however, has rarely been performed. Such investigations are useful for at least two reasons. First, there is a priori need to identify high risk sites with respect to crash. Second, it is generally believed that different crash types (e.g. rear-end, angle etc.) are associated with road geometry, the environment and traffic condition, and as a result justifying the inside causes of such crashes helps with understanding and improving the specific ability to make effective countermeasures. Therefore, the objectives of this paper are to (1) demonstrate that different crash types are associated to intersections in different ways and (2) reveal that the statistics of intersection crashes may lead to greater insights considering crash occurrence and countermeasure effectiveness. This paper first divides crashes into 5 categories or types: pedestrian-involved, rear-end, head-on, angle and sideswipe crash types. Based on 3208 crashes collected on the intersections in the city of Harbin during the period of 1992–2008, distribution, overall count and the occurrence of rate features are estimated resulting in two models. The performed analysis reveals that safety improvement factors such as the presence of a signal light set, a traffic monitoring device and ITS measure have a positive association with intersection crash in different ways, suggesting that different traffic control and management aspects may be helpful in identifying specific countermeasures in the overall safety improvement project. [ABSTRACT FROM PUBLISHER]

Abstract: To better understand how the traffic control can affect vehicle emissions, a novel TRaffic And Vehicle Emission Linkage (TRAVEL) approach was developed based on local traffic activity and emission data. This approach consists of a two-stage mapping from general traffic information to traffic flow patterns, and then to the aggregated emission rates. 39 traffic flow patterns and corresponding emission rates for light-duty and heavy-duty vehicles considering emission standards classification are generated. As a case study, vehicle activity and emissions during the Beijing Olympics were simulated and compared to BAU scenario. Approximately 42–65% of the gaseous pollutants and 24% of the particle pollutants from cars, taxies and buses were reduced. These results are validated by traffic and air quality monitoring data during the Olympics, as well as other emission inventory studies. This approach improves the ability to fast predict emission variation from traffic control measurements in several typical Chinese cities. Comments related to application of this approach with both advantages and limitations are included. [Copyright &y& Elsevier]

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]

Abstract: The Yangtze River Delta (YRD), one of the fastest developing regions in China, was investigated for its trace element concentrations. Forty-three samples of atmospheric deposition were analyzed for their concentrations of thirteen elements, As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, S and Zn. The results show that, in comparison with Chinese soil, the atmospheric deposition in the YRD generally has elevated trace element concentrations, except for Fe and Mn. The current atmospheric deposition of Cd, Cr, Cu, Pb and Zn in the YRD is significantly higher than the results from previous studies in other regions around the world. Four main sources of the trace elements were identified using statistical techniques including descriptive, correlation, and multivariate analyses, such as principal component analysis (PCA) and cluster analysis (CA). The four sources and associated cluster elements are: (1) road traffic emissions contributing As, Hg, Cu, Cd, Mo, S and Zn; (2) pyrometallurgical processes associated with Cr and Ni; (3) resuspension of soil particles contributing Fe and Mn; (4) coal combustion associated with Pb and Se. The four major sources were further verified by enrichment factor (EF) calculation and spatial analysis. Spatial distributions of four factor scores and EFs of elements show that high scores and EFs of trace metals (As, Hg, Cu, Cd, Mo, S and Zn) are mostly concentrated in the sites with high traffic conditions, and high scores of Fe and Mn are found at rural sites associated with high impact of soil particles resuspension, while Cr and Ni are higher in the area with long history of alloy machining. [Copyright &y& Elsevier]

Abstract: In order to investigate the air quality and the abatement of traffic-related pollution during the 2008 Olympic Games, we select 12 avenues in the urban area of Beijing to calculate the concentrations of PM10, CO, NO2 and O3 before and during the Olympic traffic controlling days, with the OSPM model. Through comparing the modeled results with the measurement results on a representative street, the OSPM model is validated as sufficient to predict the average concentrations of these pollutants at street level, and also reflects their daily variations well, i.e. CO presents the similar double peaks as the traffic flow, PM10 concentration is influenced by other sources. Meanwhile, the model predicts O3 to stay less during the daytime and ascend in the night, just opposite to NO2, which reveals the impact of photochemical reactions. In addition, the predicted concentrations on the windward side often exceed the leeward side, indicating the impact of the special street shape, as well as the wind. The comparison between the predicted street concentrations before and during the Olympic traffic control period shows that the overall on-road air quality was improved effectively, due to the 32.3% traffic flow reduction. The concentrations of PM10, CO and NO2 have reduced from 142.6 μg m−3, 3.02 mg m−3 and 118.7 μg m−3 to 102.0 μg m−3, 2.43 mg m−3 and 104.1 μg m−3. However, the different pollutants show diverse changes after the traffic control. PM10 decreases most, and the reduction effect focusing on the first half-day even clears the morning peak, whereas CO and NO2 have even reductions to minify the daily fluctuations on the whole. Opposite to the other pollutants, ozone shows an increase of concentration. The average reduction rate of PM10, CO, NO2 and O3 are respectively 28%, 19.3%, 12.3% and −25.2%. Furthermore, the streets in east, west, south and north areas present different air quality improvements, probably induced by the varied background pollution in different regions around Beijing, along with the impact of wind force. This finding suggests the pollution control in the surrounding regions, not only in the urban area. [Copyright &y& Elsevier]

Abstract: Automobile exhaust emissions are becoming increasingly serious with the drastic increase of the number of vehicles in Beijing. In order to investigate the air pollution level and characteristics in the areas near the main traffic lines in Beijing and to identify the contributions from traffic and other sources, gaseous pollutants including NOx, CO, O3, SO2, and meteorological parameters have been monitored at a monitoring site and a contrasting site in winter and summer in 2006. The volumes of vehicles on Beiyuan Road were recorded. The average concentrations of NO, NO2, NOx, CO, O3, and SO2 at the monitoring site were 0.148 mg/m3, 0.107 mg/m3, 0.333 mg/m3, 5.110 mg/m3, 0.006 mg/m3, and 0.157 mg/m3, respectively during the sampling period in winter and 0.021 mg/m3, 0.068 mg/m3, 0.101 mg/m3, 4.170 mg/m3, 0.083 mg/m3, and 0.056 mg/m3, respectively in summer. The high concentrations of CO and O3 reflect the influence of vehicles emission near the traffic lines evidently. The higher concentrations of CO, NO and O3 in summer may indicate that the characteristics of traffic pollution were more pronounced in summer. Results of regression analysis showed that in winter the concentrations of SO2 and CO were significantly positively correlated with the emission of heating boilers at night and negatively correlated with wind speed in daytime. The concentrations of NO and NOx were negatively correlated with wind speed, positively correlated with emission of heating boilers in daytime and positively correlated with traffic density at nighttime. The concentrations of NO2 were positively correlated with the emission of heating boilers in daytime and traffic density at nighttime. In summer, the air quality at the monitoring site and the contrasting site was mainly influenced by the traffic emissions. [Copyright &y& Elsevier]