Urban Trunk Road Research Articles

The Impact of Road Functions on Road Congestions Based on POI Clustering: An Empirical Analysis in Xi’an, China

In new-tier cities with rapid urbanization, the reorganization of urban spatial functions and the development of road networks have brought novel challenges to traffic congestion control. Urban land use patterns have a significant correlation with urban traffic congestion. However, whether and how land use patterns of cities close to the roads affect road congestion is less to be discussed. This article investigated the relationship between land use patterns close to the urban trunk road network and traffic congestion in new tier cities Xi’an, China. We adopted the DBSCAN algorithm to cluster POIs and use the mixed POI clusters to label the socio-economic functions of roads. We found the spatial heterogeneity of POIs on the trunk road network and identified the impacts of the scales and types of POI on road congestion based on the empirical analysis. Compared to the POIs as origin and destination of the trips, the POIs as stopover points of the trips cause significantly more road congestion. The POIs with bidirectional flows at entrances/exits are more likely to cause road congestion than the POIs with unidirectional flows. Moreover, the POIs with flexible traffic flows increase road congestion, while the POIs with predicted traffic flows have no statistically significant correlation with road congestion. The results help urban planners to plan the scale, type, and location of POIs close to roads and to optimize the socio-economic functions of roads and alleviate road congestion.

Research on air pollution characteristics and planning strategy of urban street environment

Dense buildings in modern cities make street pollutants more and more difficult to disperse, and the exposure level of urban residents to pollutants has increased significantly. This study focuses on the spatial and temporal distribution of ambient air pollution in urban streets and the relationship between street morphology and pollutant dispersion, and explores ways to reduce ambient air pollution in streets through spatial design. The study used the CityGrid urban grid data monitoring station to conduct an empirical study on an urban trunk road in Wuhan during the winter of 2020 to 2021, monitoring pollutants including NO2, O3, PM2.5, and PM10. The results showed that pollutant concentration changes in the near-road environment are affected by a combination of meteorological elements and traffic flow characteristics. The wind parallel to the road is more favorable to evacuate pollutants inside the street canyon, and the ambient wind above the canyon perpendicular to the road causes vortices in the canyon that cause gaseous pollutants to accumulate on the leeward side of the canyon. The distribution of particulate pollutants is mainly related to the distance of road pollutant sources. Building access ventilation can effectively evacuate street pollutants, and NO2 and O3 decay to stable levels in shorter distance from the road than PM2.5 and PM10 in downwind direction. The future urban street planning can effectively alleviate street pollution levels through strategies such as street canyon morphology control, green landscape facilities arrangement, increasing the building interface opening, and building bottom overhead.

On-Site Experiment and Characteristics Analysis of Ground Vibrations Induced by Vehicle Loads Moving on an Urban Trunk Road

In urban areas, the ground vibrations induced by vehicle loads are becoming an increasingly serious environmental issue, especially in the planning and design of high-tech workshops. In this paper, traffic flow and ground vibrations are simultaneously measured from the vehicles moving on a trunk road in Beijing from 9:30 a.m. to 9:30 p.m. The correlation between traffic volume and ground vibration is calculated to analyze the contribution of different vehicle types and density. The characteristics of ground vibration are revealed by analyzing the experimental data from the testing points of time history and frequency variety. Moreover, the attenuation law of ground vibration is summarized and well fitted by the Bornitz model. Finally, according to existing assessment standards, the vibration levels are effectively assessed. The results indicate that the concentration of multi-peak ground vibrations in a short time period can be attributed to the combination of vibration waves induced by vehicles close to each other. Two vibration peaks were observed in the frequency range of 10 Hz to 12.5 Hz and 2.5 to 4 Hz, close to the resonant frequencies of vehicle parts. The environmental vibrations induced by road traffic may exceed the allowable values stipulated in the relevant standards, and undoubtedly influence the normal operation of precise instruments, even at a distance beyond 100 m from the source.

Vehicle Air Pollutant Emission Inventory and Characterization in Henan Province from 2016 to 2019

Based on the collected urban motor vehicle activity ownership and traffic flow of highways, combined with the mileage and source profiles of VOCs, using the emission factor method, we established high-resolution emission inventories from 2016 to 2019 for urban and 2016-based highway motor vehicles, respectively, in Henan Province, China. The results showed that gasoline vehicles, particularly minibuses and ordinary motorcycles, were the main contributors of CO, VOCs, and NH3, whereas heavy-duty and light-duty diesel trucks emitted SO2, NOx, and PM. Vehicles with China 1, China 3, and China 4 emission standards contributed significantly to pollutant emissions in the fleet. The temporal variation in traffic flow was consistent with the changes in freight and passenger traffic, with higher coefficients of variation for highways from August to October and the lowest in November. The weekly and daily changes in urban trunk roads showed distinct weekend effects and clear double-peak features, respectively. High-value emission areas were concentrated in urban centers with dense transport networks and high traffic volumes and on roads radiating outward from urban areas. The Lianhuo Expressway and the Beijing-Hong Kong-Macau Expressway were high-emission roads. Light-duty gasoline vehicles made the largest contribution to the ozone formation potential (OFP) of VOCs from motor vehicles. Five species, such as ethylene and propylene, contributed significantly to VOC emissions and OFP. The average annual growth rate of vehicle ownership from 2016 to 2019 was 5.7%. Compared with 2016, VOC emissions increased by 2.8% in 2019, whereas emissions of other pollutants showed decreasing trends of different degrees, with decreases of 76.3%, 51.7%, 50.3%, 43.1%, 16.7%, and 5.9% for SO2, PM2.5, PM10, NH3, CO, and NOx, respectively. The emission reduction percentage of each pollutant in 2019 under the control policies relative to the baseline scenario ranged from 15.6% to 82.4%.

Spatial–temporal differences in operational performance of urban trunk roads based on TPI data: The case of Qingdao

The purpose of this study is to classify and analyze the traffic performance characteristics of urban trunk roads. It can help travelers effectively avoid peak hours and crowded routes, and traffic managers formulate some refined management and control on roads. This paper extracts the operating characteristics of the trunk roads on macro level by analyzing the Traffic Performance Index (TPI) data. The trunk roads are divided into three types using the agglomerative hierarchical clustering algorithm. According to the research of the spatial–temporal principles and differences of various types in traffic performance, the links with frequent traffic jams are identified, and the mechanism of the different traffic conditions is illustrated. It can be concluded that the trunk road is good conditions in most cases. On weekdays, there are two obvious peak times every day. On weekends, TPI data shows that there is no obvious peak time, and the overall road traffic conditions on weekends are better than those on weekdays. In addition, there are significant differences in the change trajectory of the TPI data and spatial distribution of various types of trunk roads. The roads with frequent traffic jams mainly come from the first and third type.

Active lane-changing model of vehicle in B-type weaving region based on potential energy field theory

To define lane-changing time accurately and quantitatively, the influence of vehicle spacing on lane-changing time was studied using cars. Taking into account the influence of surrounding vehicles’ spacing on lane-changing, a vehicle lane-changing time model on an urban road B-type weaving section based on a potential energy field theory was proposed. The model quantitatively illustrated the influence of surrounding vehicles’ spacing on lane-changing lateral acceleration and then deduced the relationship between the lateral displacement, longitudinal displacement and time of the lane-changing vehicle. By using the aerial data of passenger cars lane-changing in the weaving area of an urban trunk road, the parameters in the model were calibrated and the lane-changing trajectory of vehicles simulated by the model was tested. It is found that the accuracy of the lane-changing model to quantitatively define the transverse acceleration while changing lanes and the spacing between constrained regions reaches 90%, and the fitting degree between simulated lane change trajectory and actual lane change trajectory is over 90%. The results show that the vehicle lane-change model based on the potential energy field theory can effectively simulate the relationship between vehicle lane-change time and lateral and longitudinal displacement and can provide theoretical and technical support for traffic simulation and multi-vehicle interaction.

Chemical characteristics and source apportionment of PM2.5 in Wuhan, China

Continuous online measurements of fine particulate matter mass (PM2.5) and its chemical composition were carried out at an urban monitoring site in Wuhan from March 2017 to February 2018. The PM2.5 mass concentration ranged from 6.3 to 223 μg/m3, with the highest in winter and the lowest in summer. Water soluble ions (WSIs) were the most abundant component in PM2.5 (28.8 ± 22.9 μg/m3), followed by carbonaceous aerosol (11.9 ± 10.4 μg/m3) and elements (5.5 ± 6.7 μg/m3). It is noteworthy that six episodes of sustained high PM were observed during the study period. Five major contributors of PM2.5 were identified by positive matrix factorization (PMF) to be the iron and steel industry, fugitive dust, secondary photochemistry, traffic-related emission and biomass burning, contributing 26.3%, 5.5%, 29.5%, 29.2% and 9.6% to PM2.5, respectively. Furthermore, conditional probability function (CPF), trajectory analysis and potential source contribution function (PSCF) were used to identify the influences of local activities and regional source. Local sources mainly include Wuhan iron and steel group, construction sites and urban trunk roads, etc. Three pollution transport pathways of PM2.5 in Wuhan were identified to be northwest, east and south pathway, with the relative contribution of 40%, 17% and 43%, respectively. Western Henan, northern Shaanxi and southwestern Shanxi were identified to be the major potential source regions of PM2.5 in Wuhan.

Research on Speed Limit Value Model and Evaluation Method of Urban Trunk Road

To reduce the probability or severity of traffic accidents, improve traffic capacity of road, and ensure efficient operation of traffic flow, speed limits have become an important traffic management method of urban truck road. Based on detailed analysis of the current method of determining the speed limit, multifactorial method of determining and evaluating speed limit is proposed. Firstly, considering the safety speed of linear and steady flow, determining the reference value, and the influence of the number of entrances and exits, road width, roadside disturbance, and road conditions are set as correction factors. Then the model of determining the speed limit value is established. Speed scatter and ratio of maximum-minimum of car-truck are put forward as elevation index. At last, a project example is provided to prove the method.

Estimating the effects of “community opening” policy on alleviating traffic congestion in large Chinese cities by integrating ant colony optimization and complex network analyses

According to an urban planning directive issued by the Chinese Central Government in early 2016, the Community Opening Policy will be put on the agenda to ameliorate transportation networks, which has aroused much attention regarding the coming changes in traffic, especially in road network structures. Nevertheless, few studies were concerned with the direct and indirect impacts of opening gated communities. This study aims to analyze the impact of opening gated communities on road structure by integrating ant colony optimization (ACO) and complex graph theory and to investigate its influence on resident commuting efficiency and the traffic flow centroid. First, with a traffic road network based on OpenStreetMap (OSM), alteration in the connectivity between two road nodes and the resident overall commuting time and distance are computed using an ACO algorithm. Second, using complex graph theory, the attraction index of every road is calculated, and the congestion area before and after the opening policy is obtained. The research areas include Beijing, Shanghai, Guangzhou, and Shenzhen, which are first-tier Chinese cities. The results demonstrate that opening gated communities will increase the connectivity and accessibility of the current road network by 9.43–29.80%, generating a decrease of 2.57–4.50% in resident commuting time for short-distance travel. Furthermore, with the decline in traffic stream in the urban trunk roads, the number of potentially congested junctions will decrease, resulting in an alteration in the spatial position and coverage area of the urban congestion areas. This study carried out quantitative research into the effect of opening gated communities, providing a reference for urban planners and government.

A Method for Traffic Congestion Clustering Judgment Based on Grey Relational Analysis

Traffic congestion clustering judgment is a fundamental problem in the study of traffic jam warning. However, it is not satisfactory to judge traffic congestion degrees using only vehicle speed. In this paper, we collect traffic flow information with three properties (traffic flow velocity, traffic flow density and traffic volume) of urban trunk roads, which is used to judge the traffic congestion degree. We first define a grey relational clustering model by leveraging grey relational analysis and rough set theory to mine relationships of multidimensional-attribute information. Then, we propose a grey relational membership degree rank clustering algorithm (GMRC) to discriminant clustering priority and further analyze the urban traffic congestion degree. Our experimental results show that the average accuracy of the GMRC algorithm is 24.9% greater than that of the K-means algorithm and 30.8% greater than that of the Fuzzy C-Means (FCM) algorithm. Furthermore, we find that our method can be more conducive to dynamic traffic warnings.

Detection and Evaluation of Ling Bridge in Ningbo

Ling Bridge in Ningbo, a province-protected historic relic in Zhejiang, is the only three-hinged steel arch bridge existing in China as well as the first modern steel arch bridge co-constructed by Chinese engineers and foreign engineers in 1936. For over 70 years the bridge has served as an important transportation node on urban trunk road, bearing significant traffic pressure. It is necessary to have its status quo detected and its safe use evaluated to sustain normal operation of the bridge. The status assessment of the bridge is conducted in the following aspects: first, visual inspection was applied to check types of existing diseases and to estimate their threat degrees to the bridge; then, spatial linear examination was applied to detect structural deformation and to calculate whether there exists a instability hazard; finally, strength and fatigue calculation was made to determine safety degree of the bridge structure.

Study on Structural Design and Driving Process of Subway Station Passageway Crossing Urban Trunk Road by Tunneling Method

On the basis of unfavorable geology of a passageway in subway station to cross urban trunk road with heavy traffic flow in Chengdu city, the comparison of two different driving methods for the underground passageway with three arches and two pillars is carried out in the paper. The result shows that both center drift-pillar method and partial bench-cut method can be used to build the passageway in the subway station. But the latter is superior to the former in reducing construction cost, risk and timescale. While the former is more efficient in controlling ground subsidence. The tubular roof protection is also designed to reinforce the shear strength of soil above the crown of the passageway before excavating the poor surrounding soil. The inventive driving procedure of partial bench-cut method presented in the paper can be utilized to guide the rational design and economical construction of shallow passageway for subway station to cross urban trunk road in weak geological strata.

Pollution and health risk of potentially toxic metals in urban road dust in Nanjing, a mega-city of China

Spatial variations in concentrations of a suite of potentially toxic metals (Ba, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and Ca in road dusts (n=99) from urban trunk roads (TR) in Nanjing, a mega-city in China, were established. Metal pollution levels, sources and human health risk (non-carcinogenic) were studied. In contrast to previous studies, we labeled the indicative metals relating to non-exhaust traffic emissions by comparing metal pollution between crossroad and park road dusts, and then anthropogenic sources of metals in TR dusts were assessed combining their spatial pollution patterns, principal component analysis and Pb isotopic compositions. Results showed that the metals were enriched in TR dusts compared to background soil concentrations with mean enrichment factors (EFs) of 2.2–23, indicating considerable anthropogenic influence. The degrees of metal pollution ranged from minimal to extremely high and ranked by Ca>Cu>Pb≈Zn>Cr≈Fe>Ni≈Ba>Mn on average. Pollution of Cr, Cu, Fe, Mn, Ni, Pb and Zn in TR dusts resulted primarily from industrial emissions (e.g., coal combustion and smelting) and high pollution levels were found close to suburb industrial complexes, whereas pollution of Ba and Ca was mainly related to construction/demolition sources and was generally distributed homogeneously. The relatively minor contribution of non-exhaust traffic emissions to metal pollution in TR dusts was considered to be due to overwhelming industrial and construction/demolition contributions, as well as to the dilution effect of natural soil particles. Ingestion appears to be the major route of exposure for road dust for both adults and children, followed by dermal contact. The non-carcinogenic health risk resulting from exposure to the potentially toxic metals in TR dusts was within the safe level based on the Hazard Index (HI), except in pollution hotspots where exposure to Pb, Cr, and Cu may be hazardous to children.

Traffic Signal Control for Urban Trunk Road Based on Wireless Sensor Network and Intelligent Algorithm

Abstract Based on the analysis for the present research on controlling urban trunk road, a intelligent control method for urban trunk road based on wireless sensor and fuzzy neural network was proposed. In this method, we took two layers of WSN structure. The first one was data collecting layer, which consisted of traffic information collecting nodes and sink nodes. Data collecting layer was responsible for collecting vehicle information at single crossing, transmitted to the second layer after data fusion. The second one was control layer, composed of traffic light controller nodes in which fuzzy neural controller was nested. Traffic light controller nodes were used to accept the traffic data detected by the first layer, and fuzzy neural controller determined the signal cycle at artery, and on-line adjusted the green ratio at all directions on crossroads to accomplish traffic light control. Simulating results showed that the method is superior to the common fuzzy control, effectively reducing queue length, so as to reach the purpose of decreasing vehicle delay.

Research and Evaluation on the Coordinated Control System in Urban Trunk Road Contained Pedestrian Crossing

We analyze the road environment of the present urban main road and the motor vehicle traffic conditions firstly, from which we see that crosswalks should be added and some intersections should be signal control optimized. Then using the timing linear control system theory which is suitable for China, the paper optimizes the crosswalk and intersection signal timing. Simulation is conducted with simulation software of VISSIM in the end, obtaining that after arterial road coordination, although a crosswalk is added in optimized arterial road, the total stop delay and the travel time of the mainstream vehicles are effectively reduced. The program satisfies the need for pedestrian crossing, and obtains better green wave band of arterial road.

Spatial and diurnal variations in concentration of atmospheric NO<SUB align=right>x along urban-rural roadways in Nanjing, Southeastern China

Atmospheric NOx concentrations (including NO2 and NO) on the roadside environments of urban trunk, belt highway and suburban road as well as a reference in a forest area were measured. NOx concentrations on roadside environments tended to be higher than that on the reference. With the exception of suburban road, NOx concentrations over both of the urban trunk and belt highway exceeded the limited value of National Air Environmental Quality Standards. Gradient measurement of NOx on the downwind side of the belt highway shows that it declined to background level over 100 m from the road edge.

A Study on Environmental Impact Costs of Urban Trunk Roads

A Study on Environmental Impact Costs of Urban Trunk Roads