Urban road construction and the laying of underground pipelines are both important elements in the improvement of urban infrastructure,while the construction of the two may affect and restrict each other if they are n...Urban road construction and the laying of underground pipelines are both important elements in the improvement of urban infrastructure,while the construction of the two may affect and restrict each other if they are not planned systematically.Therefore,a synergistic design of urban roads and pipelines is needed to ensure the synergy of urban road construction and underground pipeline laying.This paper mainly analyzes the necessity of building information modeling(BIM)technology application in the collaborative planning and design of urban roads and pipelines,and explores the application strategy of BIM technology.展开更多
Road traffic flow forecasting provides critical information for the operational management of road mobility challenges, and models are used to generate the forecast. This paper uses a random process to present a novel...Road traffic flow forecasting provides critical information for the operational management of road mobility challenges, and models are used to generate the forecast. This paper uses a random process to present a novel traffic modelling framework for aggregate traffic on urban roads. The main idea is that road traffic flow is random, even for the recurrent flow, such as rush hour traffic, which is predisposed to congestion. Therefore, the structure of the aggregate traffic flow model for urban roads should correlate well with the essential variables of the observed random dynamics of the traffic flow phenomena. The novelty of this paper is the developed framework, based on the Poisson process, the kinematics of urban road traffic flow, and the intermediate modelling approach, which were combined to formulate the model. Empirical data from an urban road in Ghana was used to explore the model’s fidelity. The results show that the distribution from the model correlates well with that of the empirical traffic, providing a strong validation of the new framework and instilling confidence in its potential for significantly improved forecasts and, hence, a more hopeful outlook for real-world traffic management.展开更多
The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networ...The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networks,the dynamic partitioning of urban regions reflecting the propagation of congestion remains an open question.This paper proposes to partition the network into homogeneous sub-regions based on random walk algorithm.Starting from selected random walkers,the road network is partitioned from the early morning when congestion emerges.A modified Akaike information criterion is defined to find the optimal number of partitions.Region boundary adjustment algorithms are adopted to optimize the partitioning results to further ensure the correlation of partitions.The traffic data of Melbourne city are used to verify the effectiveness of the proposed partitioning method.展开更多
In order to solve navigation problem of intelligent vehicle driving on urban roads and to achieve the navigation in intersection area, intersection transition area and section area. The relay navigation strategy and a...In order to solve navigation problem of intelligent vehicle driving on urban roads and to achieve the navigation in intersection area, intersection transition area and section area. The relay navigation strategy and algorithm can solve the navigation problem of intelligent vehicle driving in typical urban roads such as intersection area, intersection transition area and section area, realizing seamless handover among different typical areas. Bezier curve function model was introduced to different typical areas, which solved the self-adaption recognition problem in different typical areas and revised positional accuracy with the help of cloud computing positioning service. In order to explain the strategy implement, an instance based on the strategy was adopted. Instance analysis indicates that as for the navigation problem in intersection area, intersection transition area and section area, if the relay navigation strategy is utilized, the self-adaption recognition problem in different typical areas can be handled. Based on the relay navigation strategy, the drive of intelligent vehicle on urban roads can effectively solve the self-adaption recognition problem in different typical areas in urban and further solve driving problems of intelligent vehicle of the same category in urban roads.展开更多
In this paper, platoons of autonomous vehicles operating in urban road networks are considered. From a methodological point of view, the problem of interest consists of formally characterizing vehicle state trajectory...In this paper, platoons of autonomous vehicles operating in urban road networks are considered. From a methodological point of view, the problem of interest consists of formally characterizing vehicle state trajectory tubes by means of routing decisions complying with traffic congestion criteria. To this end, a novel distributed control architecture is conceived by taking advantage of two methodologies: deep reinforcement learning and model predictive control. On one hand, the routing decisions are obtained by using a distributed reinforcement learning algorithm that exploits available traffic data at each road junction. On the other hand, a bank of model predictive controllers is in charge of computing the more adequate control action for each involved vehicle. Such tasks are here combined into a single framework:the deep reinforcement learning output(action) is translated into a set-point to be tracked by the model predictive controller;conversely, the current vehicle position, resulting from the application of the control move, is exploited by the deep reinforcement learning unit for improving its reliability. The main novelty of the proposed solution lies in its hybrid nature: on one hand it fully exploits deep reinforcement learning capabilities for decisionmaking purposes;on the other hand, time-varying hard constraints are always satisfied during the dynamical platoon evolution imposed by the computed routing decisions. To efficiently evaluate the performance of the proposed control architecture, a co-design procedure, involving the SUMO and MATLAB platforms, is implemented so that complex operating environments can be used, and the information coming from road maps(links,junctions, obstacles, semaphores, etc.) and vehicle state trajectories can be shared and exchanged. Finally by considering as operating scenario a real entire city block and a platoon of eleven vehicles described by double-integrator models, several simulations have been performed with the aim to put in light the main f eatures of the proposed approach. Moreover, it is important to underline that in different operating scenarios the proposed reinforcement learning scheme is capable of significantly reducing traffic congestion phenomena when compared with well-reputed competitors.展开更多
In urban road greening,the planting of ground cover flowers is essential,and herbaceous flowers are an important part.Through the investigation on the diversity of herbaceous flowers in urban road green spaces of Hefe...In urban road greening,the planting of ground cover flowers is essential,and herbaceous flowers are an important part.Through the investigation on the diversity of herbaceous flowers in urban road green spaces of Hefei City,the types,colors,application frequency and planting of herbaceous flowers in urban road green spaces were statistically analyzed,and the application forms of herbaceous flowers in the road greening of Hefei City were studied.The characteristics and problems of herbaceous flowers in the road greening of Hefei City were found,and some development suggestions were put forward.展开更多
The number of urban underground road tunnels in China is increasing year by year,and health monitoring of tunnels is an effective management method to ensure their structural integrity.However,for shorter underground ...The number of urban underground road tunnels in China is increasing year by year,and health monitoring of tunnels is an effective management method to ensure their structural integrity.However,for shorter underground road tunnel projects,insufficient investment often leads to less frequent application of health monitoring systems.The application of intelligent structural health monitoring means can not only reduce the project cost but also help workers fully understand the actual situation of the tunnel structure.Therefore,this paper analyzes the characteristics,problems,and design of the urban underground road tunnel structural health monitoring system,and discusses the implementation of the urban underground road tunnel structural health monitoring system.展开更多
The importance and complexity of prioritizing construction projects (PCP) in urban road network planning lead to the necessity to develop an aided decision making program (ADMP). Cost benefit ratio model and stage rol...The importance and complexity of prioritizing construction projects (PCP) in urban road network planning lead to the necessity to develop an aided decision making program (ADMP). Cost benefit ratio model and stage rolled method are chosen as the theoretical foundations of the program, and then benefit model is improved to accord with the actuality of urban traffic in China. Consequently, program flows, module functions and data structures are designed, and particularly an original data structure of road ...展开更多
Heterogeneity is one of those characteristics which differentiate traffic conditions of a developing country from other developed nations.The heterogeneity which represents the diversity among vehicle categories is su...Heterogeneity is one of those characteristics which differentiate traffic conditions of a developing country from other developed nations.The heterogeneity which represents the diversity among vehicle categories is suspected to have adverse influences on lane discipline,congestion potential,and road users’safety.However,the influence of heterogeneity on the above-mentioned parameters has been only measured indirectly by considering traffic composition as an indicator of the prevailed heterogeneity-level.No direct relationship between the heterogeneity and other parameters has been established as there is no methodology available yet for quantifying the heterogeneity of mixed traffic.The present study addresses this problem and conceptualizes the‘Heterogeneity Index’(HI)to quantify the heterogeneity present in a mixed traffic stream.HI is conceived as a measure of the dispersion of Passenger Car Units(PCU)for different vehicle categories from its central value.A higher value of HI signifies more diverse vehicle categories present in the traffic stream.PCU of a vehicle category was estimated using the speed-based method and the individual speeds were predicted based on classified volumes using the Gaussian Process Regression model developed in this study.This paper also recommends several categorical levels for easy perception about the intensity of heterogeneity.Further,the sensitivity analysis explored the dynamic aspects of HI.Results showcased how the HI of a traffic stream may vary subject to the combined or the individual change in traffic volume,traffic composition and classified speeds.The outcomes of the study will be useful to estimate the intensity of heterogeneity that prevailed within a mixed traffic stream with varying traffic conditions.展开更多
In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were d...In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were defined under special conditions.The link travel time model(ice and snowfall based-bureau public road,ISB-BPR) and the path choice decision model(elastic demand user equilibrium,EDUE) were proposed.The integrated reliability was defined and the model was set up.Monte Carlo simulation was used to calculate the model and a numerical example was provided to demonstrate the application of the model and efficiency of the solution algorithm.The results show that the intensity of ice and snowfall,the traffic demand and supply,and the requirements for level of service(LOS) have great influence on the reliability of a road network.For example,the reliability drops from 65% to 5% when the traffic demand increases by 30%.The comprehensive performance index may be used for network planning,design and maintenance.展开更多
The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, ...The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, a morphological method is proposed. The proposed method combines the automatic thresholding and morphological operation techniques to extract the road centerline of the urban environment. This method intends to solve urban road centerline problems, vehicle, vegetation, building etc. Based on this morphological method, an object extractor is designed to extract road networks from highly remote sensing images. Some filters are applied in this experiment such as line reconstruction and region filling techniques to connect the disconnected road segments and remove the small redundant. Finally, the thinning algorithm is used to extract the road centerline. Experiments have been conducted on a high-resolution IKONOS and QuickBird images showing the efficiency of the proposed method.展开更多
An adaptive fuzzy logic controller (AFC) is presented for the signal control of the urban traffic network. The AFC is composed of the signal control system-oriented control level and the signal controller-oriented fuz...An adaptive fuzzy logic controller (AFC) is presented for the signal control of the urban traffic network. The AFC is composed of the signal control system-oriented control level and the signal controller-oriented fuzzy rules regulation level. The control level decides the signal timings in an intersection with a fuzzy logic controller. The regulation level optimizes the fuzzy rules by the Adaptive Rule Module in AFC according to both the system performance index in current control period and the traffic flows in the last one. Consequently the system performances are improved. A weight coefficient controller (WCC) is also developed to describe the interactions of traffic flow among the adjacent intersections. So the AFC combined with the WCC can be applied in a road network for signal timings. Simulations of the AFC on a real traffic scenario have been conducted. Simulation results indicate that the adaptive controller for traffic control shows better performance than the actuated one.展开更多
Highway is an important kind of infrastructure which the transportation sector depends on.The rationality of the interchange design between urban roads and expressways is related to the relieving of urban traffic pres...Highway is an important kind of infrastructure which the transportation sector depends on.The rationality of the interchange design between urban roads and expressways is related to the relieving of urban traffic pressure.Based on the status quo of interchange design between urban roads and expressways,this paper discusses the types and applications of interchange design,hoping to provide reference for the design and construction of highway projects and ensure the rationality of interchange design.展开更多
Urban traffic and urban environmental pollution are important issues that must be taken into account in the process of urbanization,especially in China.Modernization has enabled many developed countries in the west to...Urban traffic and urban environmental pollution are important issues that must be taken into account in the process of urbanization,especially in China.Modernization has enabled many developed countries in the west to carry out rational city traffic planning.At the same time,the concept of green transportation has also emerged,integrating low-energy consumption,low pollution,comfort,and safety into urban traffic to effectively solve issues pertaining to traffic and pollution.The concept of green transportation has been widely adopted in China and made popular in many cities,thereby promoting the sustainable development of cities.展开更多
In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow running characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16%...In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow running characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16% , speed is decreased by 30% , and start-up lost time is increased by 27%. Based on the signal control theory of HCM and Webster, the character values of traffic flow in different urban road environments were investigated, and the evolvement regularity of signal control parameters such as cycle, split, green time, offset, yellow time and red time in snow-icy road environment was analyzed. The impact factors and the changes in the scope of signal control parameters were achieved. Simulation results and practical application show that the signal control plan of road enviromnent without snow and ice will increase the vehicle delay, stop length and traffic congestion in snow-icy road environment. Thus, the traffic signal control system should address a suitable signal control plan based on different road environments.展开更多
Urban road pricing schemes are becoming increasingly popular among researchers and politicians as they promise a handle on increasing inner city traffic and economy as well as sustainable improvements for cities facin...Urban road pricing schemes are becoming increasingly popular among researchers and politicians as they promise a handle on increasing inner city traffic and economy as well as sustainable improvements for cities facing huge congestion and pollution problems. As in the cases of London and Stockholm, many European cities are going to implement such toll systems, especially as also the European Commission is voting for such pricing schemes in the recent white book on transportation and traffic, This research therefore provides a description of different urban road pricing schemes, their cost implications for city （last mile） transport as well as the decision and management options derived from these schemes for logistics companies. These options are furthermore checked regarding their advantages and disadvantages under the described toll schemes.展开更多
Driven by the rapid economic development,the development of transportation in China has begun to move towards mountainous areas.The climate environment,topography and landform of mountainous cities are different from ...Driven by the rapid economic development,the development of transportation in China has begun to move towards mountainous areas.The climate environment,topography and landform of mountainous cities are different from those of plain areas.In mountainous cities,the area of opposite interchanges between expressways and urban roads is generally large,which has a certain contradiction with the topographic conditions of mountainous cities.Therefore,it is necessary to reasonably design the opposite interchanges between expressways and urban roads in mountainous cities.The author explores and analyzes the factors restricting the special-shaped interchange between expressway and urban road in mountainous cities and the main fbnns of special-shaped interchange,and puts forward a reasonable design scheme,hoping to make a smooth development of the special-shaped interchange in mountainous cities.展开更多
In order to promote the development of urban roads,enhance urban road design,and fully maximize the role of urban roads,this study first discusses the fundamental requirements of urban road design,the“humanized”conc...In order to promote the development of urban roads,enhance urban road design,and fully maximize the role of urban roads,this study first discusses the fundamental requirements of urban road design,the“humanized”concept in urban road design,and the importance of“humanized”urban road design,as well as proposes several“humanized”design strategies for urban roads as references.展开更多
Road runoffs were sampled from five highways and five urban roads located in the New Juaben Municipality during the late storm events in the month of November 2014 and the early storm events in January 2015. A variety...Road runoffs were sampled from five highways and five urban roads located in the New Juaben Municipality during the late storm events in the month of November 2014 and the early storm events in January 2015. A variety of water quality parameters such as, pH, temperature, turbidity, electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), aqueous concentrations of Chloride (Cl<sup>-</sup>), Phosphate (), Nitrate () and Sulphate () ions as well as the total concentrations of some selected heavy metals (Fe, Cu, Zn, Pb, Cd, Ni and Cr) were analysed for both periods. Although the results for the studied parameters, particularly the heavy metals varied for both sampling periods, the general trend indicated an increase in accumulation from November 2014 to January 2015. This was attributed to vehicular deposition as well as other natural and anthropogenic depositions on the road surfaces during the antecedent dry weather period between the two sampling months. The highest increase in pollutant loadings was associated with the heavy metals and some physico-chemical parameters such as TSS, TDS, EC and turbidity. Generally, EC, TDS, TSS and turbidity were above the permissible limits of the Environmental Protection Agency (EPA) of Ghana for both sampling periods. However, almost all the mean concentrations of heavy metals recorded for both road runoffs and the control samples were within the permissible limits of the Ghana EPA with some few exceptions.展开更多
文摘Urban road construction and the laying of underground pipelines are both important elements in the improvement of urban infrastructure,while the construction of the two may affect and restrict each other if they are not planned systematically.Therefore,a synergistic design of urban roads and pipelines is needed to ensure the synergy of urban road construction and underground pipeline laying.This paper mainly analyzes the necessity of building information modeling(BIM)technology application in the collaborative planning and design of urban roads and pipelines,and explores the application strategy of BIM technology.
文摘Road traffic flow forecasting provides critical information for the operational management of road mobility challenges, and models are used to generate the forecast. This paper uses a random process to present a novel traffic modelling framework for aggregate traffic on urban roads. The main idea is that road traffic flow is random, even for the recurrent flow, such as rush hour traffic, which is predisposed to congestion. Therefore, the structure of the aggregate traffic flow model for urban roads should correlate well with the essential variables of the observed random dynamics of the traffic flow phenomena. The novelty of this paper is the developed framework, based on the Poisson process, the kinematics of urban road traffic flow, and the intermediate modelling approach, which were combined to formulate the model. Empirical data from an urban road in Ghana was used to explore the model’s fidelity. The results show that the distribution from the model correlates well with that of the empirical traffic, providing a strong validation of the new framework and instilling confidence in its potential for significantly improved forecasts and, hence, a more hopeful outlook for real-world traffic management.
基金Project supported by the National Natural Science Foundation of China(Grant No.12072340)the Chinese Scholarship Council and the Australia Research Council through a linkage project fund。
文摘The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networks,the dynamic partitioning of urban regions reflecting the propagation of congestion remains an open question.This paper proposes to partition the network into homogeneous sub-regions based on random walk algorithm.Starting from selected random walkers,the road network is partitioned from the early morning when congestion emerges.A modified Akaike information criterion is defined to find the optimal number of partitions.Region boundary adjustment algorithms are adopted to optimize the partitioning results to further ensure the correlation of partitions.The traffic data of Melbourne city are used to verify the effectiveness of the proposed partitioning method.
基金supported by the National Natural Science Foundation of China (61035004, 61273213, 61300006, 61305055, 90920305, 61203366)
文摘In order to solve navigation problem of intelligent vehicle driving on urban roads and to achieve the navigation in intersection area, intersection transition area and section area. The relay navigation strategy and algorithm can solve the navigation problem of intelligent vehicle driving in typical urban roads such as intersection area, intersection transition area and section area, realizing seamless handover among different typical areas. Bezier curve function model was introduced to different typical areas, which solved the self-adaption recognition problem in different typical areas and revised positional accuracy with the help of cloud computing positioning service. In order to explain the strategy implement, an instance based on the strategy was adopted. Instance analysis indicates that as for the navigation problem in intersection area, intersection transition area and section area, if the relay navigation strategy is utilized, the self-adaption recognition problem in different typical areas can be handled. Based on the relay navigation strategy, the drive of intelligent vehicle on urban roads can effectively solve the self-adaption recognition problem in different typical areas in urban and further solve driving problems of intelligent vehicle of the same category in urban roads.
文摘In this paper, platoons of autonomous vehicles operating in urban road networks are considered. From a methodological point of view, the problem of interest consists of formally characterizing vehicle state trajectory tubes by means of routing decisions complying with traffic congestion criteria. To this end, a novel distributed control architecture is conceived by taking advantage of two methodologies: deep reinforcement learning and model predictive control. On one hand, the routing decisions are obtained by using a distributed reinforcement learning algorithm that exploits available traffic data at each road junction. On the other hand, a bank of model predictive controllers is in charge of computing the more adequate control action for each involved vehicle. Such tasks are here combined into a single framework:the deep reinforcement learning output(action) is translated into a set-point to be tracked by the model predictive controller;conversely, the current vehicle position, resulting from the application of the control move, is exploited by the deep reinforcement learning unit for improving its reliability. The main novelty of the proposed solution lies in its hybrid nature: on one hand it fully exploits deep reinforcement learning capabilities for decisionmaking purposes;on the other hand, time-varying hard constraints are always satisfied during the dynamical platoon evolution imposed by the computed routing decisions. To efficiently evaluate the performance of the proposed control architecture, a co-design procedure, involving the SUMO and MATLAB platforms, is implemented so that complex operating environments can be used, and the information coming from road maps(links,junctions, obstacles, semaphores, etc.) and vehicle state trajectories can be shared and exchanged. Finally by considering as operating scenario a real entire city block and a platoon of eleven vehicles described by double-integrator models, several simulations have been performed with the aim to put in light the main f eatures of the proposed approach. Moreover, it is important to underline that in different operating scenarios the proposed reinforcement learning scheme is capable of significantly reducing traffic congestion phenomena when compared with well-reputed competitors.
基金Sponsored by the Innovation Training Project for College Students in Anhui Province(S202212216130)Key Research Project of Natural Science in Universities of Anhui Province(2023AH051816)General Teaching Research Project of Anhui Province(2022jyxm665).
文摘In urban road greening,the planting of ground cover flowers is essential,and herbaceous flowers are an important part.Through the investigation on the diversity of herbaceous flowers in urban road green spaces of Hefei City,the types,colors,application frequency and planting of herbaceous flowers in urban road green spaces were statistically analyzed,and the application forms of herbaceous flowers in the road greening of Hefei City were studied.The characteristics and problems of herbaceous flowers in the road greening of Hefei City were found,and some development suggestions were put forward.
文摘The number of urban underground road tunnels in China is increasing year by year,and health monitoring of tunnels is an effective management method to ensure their structural integrity.However,for shorter underground road tunnel projects,insufficient investment often leads to less frequent application of health monitoring systems.The application of intelligent structural health monitoring means can not only reduce the project cost but also help workers fully understand the actual situation of the tunnel structure.Therefore,this paper analyzes the characteristics,problems,and design of the urban underground road tunnel structural health monitoring system,and discusses the implementation of the urban underground road tunnel structural health monitoring system.
文摘The importance and complexity of prioritizing construction projects (PCP) in urban road network planning lead to the necessity to develop an aided decision making program (ADMP). Cost benefit ratio model and stage rolled method are chosen as the theoretical foundations of the program, and then benefit model is improved to accord with the actuality of urban traffic in China. Consequently, program flows, module functions and data structures are designed, and particularly an original data structure of road ...
文摘Heterogeneity is one of those characteristics which differentiate traffic conditions of a developing country from other developed nations.The heterogeneity which represents the diversity among vehicle categories is suspected to have adverse influences on lane discipline,congestion potential,and road users’safety.However,the influence of heterogeneity on the above-mentioned parameters has been only measured indirectly by considering traffic composition as an indicator of the prevailed heterogeneity-level.No direct relationship between the heterogeneity and other parameters has been established as there is no methodology available yet for quantifying the heterogeneity of mixed traffic.The present study addresses this problem and conceptualizes the‘Heterogeneity Index’(HI)to quantify the heterogeneity present in a mixed traffic stream.HI is conceived as a measure of the dispersion of Passenger Car Units(PCU)for different vehicle categories from its central value.A higher value of HI signifies more diverse vehicle categories present in the traffic stream.PCU of a vehicle category was estimated using the speed-based method and the individual speeds were predicted based on classified volumes using the Gaussian Process Regression model developed in this study.This paper also recommends several categorical levels for easy perception about the intensity of heterogeneity.Further,the sensitivity analysis explored the dynamic aspects of HI.Results showcased how the HI of a traffic stream may vary subject to the combined or the individual change in traffic volume,traffic composition and classified speeds.The outcomes of the study will be useful to estimate the intensity of heterogeneity that prevailed within a mixed traffic stream with varying traffic conditions.
基金Project(E200940) supported by the Natural Science Foundation of Heilongjiang Province, ChinaProject(2009GC20008020) supported by the Technology Research and Development Program of Shandong Province, China
文摘In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were defined under special conditions.The link travel time model(ice and snowfall based-bureau public road,ISB-BPR) and the path choice decision model(elastic demand user equilibrium,EDUE) were proposed.The integrated reliability was defined and the model was set up.Monte Carlo simulation was used to calculate the model and a numerical example was provided to demonstrate the application of the model and efficiency of the solution algorithm.The results show that the intensity of ice and snowfall,the traffic demand and supply,and the requirements for level of service(LOS) have great influence on the reliability of a road network.For example,the reliability drops from 65% to 5% when the traffic demand increases by 30%.The comprehensive performance index may be used for network planning,design and maintenance.
文摘The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, a morphological method is proposed. The proposed method combines the automatic thresholding and morphological operation techniques to extract the road centerline of the urban environment. This method intends to solve urban road centerline problems, vehicle, vegetation, building etc. Based on this morphological method, an object extractor is designed to extract road networks from highly remote sensing images. Some filters are applied in this experiment such as line reconstruction and region filling techniques to connect the disconnected road segments and remove the small redundant. Finally, the thinning algorithm is used to extract the road centerline. Experiments have been conducted on a high-resolution IKONOS and QuickBird images showing the efficiency of the proposed method.
基金National Natural Science Foundation of China (No.60774023)
文摘An adaptive fuzzy logic controller (AFC) is presented for the signal control of the urban traffic network. The AFC is composed of the signal control system-oriented control level and the signal controller-oriented fuzzy rules regulation level. The control level decides the signal timings in an intersection with a fuzzy logic controller. The regulation level optimizes the fuzzy rules by the Adaptive Rule Module in AFC according to both the system performance index in current control period and the traffic flows in the last one. Consequently the system performances are improved. A weight coefficient controller (WCC) is also developed to describe the interactions of traffic flow among the adjacent intersections. So the AFC combined with the WCC can be applied in a road network for signal timings. Simulations of the AFC on a real traffic scenario have been conducted. Simulation results indicate that the adaptive controller for traffic control shows better performance than the actuated one.
文摘Highway is an important kind of infrastructure which the transportation sector depends on.The rationality of the interchange design between urban roads and expressways is related to the relieving of urban traffic pressure.Based on the status quo of interchange design between urban roads and expressways,this paper discusses the types and applications of interchange design,hoping to provide reference for the design and construction of highway projects and ensure the rationality of interchange design.
文摘Urban traffic and urban environmental pollution are important issues that must be taken into account in the process of urbanization,especially in China.Modernization has enabled many developed countries in the west to carry out rational city traffic planning.At the same time,the concept of green transportation has also emerged,integrating low-energy consumption,low pollution,comfort,and safety into urban traffic to effectively solve issues pertaining to traffic and pollution.The concept of green transportation has been widely adopted in China and made popular in many cities,thereby promoting the sustainable development of cities.
基金Sponsored by the National Basic Research and Development Program of China(Grant No.2006CB705505) Research Fund for the Doctoral Program of Higher Education of China(Grant No.200802131012)
文摘In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow running characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16% , speed is decreased by 30% , and start-up lost time is increased by 27%. Based on the signal control theory of HCM and Webster, the character values of traffic flow in different urban road environments were investigated, and the evolvement regularity of signal control parameters such as cycle, split, green time, offset, yellow time and red time in snow-icy road environment was analyzed. The impact factors and the changes in the scope of signal control parameters were achieved. Simulation results and practical application show that the signal control plan of road enviromnent without snow and ice will increase the vehicle delay, stop length and traffic congestion in snow-icy road environment. Thus, the traffic signal control system should address a suitable signal control plan based on different road environments.
文摘Urban road pricing schemes are becoming increasingly popular among researchers and politicians as they promise a handle on increasing inner city traffic and economy as well as sustainable improvements for cities facing huge congestion and pollution problems. As in the cases of London and Stockholm, many European cities are going to implement such toll systems, especially as also the European Commission is voting for such pricing schemes in the recent white book on transportation and traffic, This research therefore provides a description of different urban road pricing schemes, their cost implications for city （last mile） transport as well as the decision and management options derived from these schemes for logistics companies. These options are furthermore checked regarding their advantages and disadvantages under the described toll schemes.
文摘Driven by the rapid economic development,the development of transportation in China has begun to move towards mountainous areas.The climate environment,topography and landform of mountainous cities are different from those of plain areas.In mountainous cities,the area of opposite interchanges between expressways and urban roads is generally large,which has a certain contradiction with the topographic conditions of mountainous cities.Therefore,it is necessary to reasonably design the opposite interchanges between expressways and urban roads in mountainous cities.The author explores and analyzes the factors restricting the special-shaped interchange between expressway and urban road in mountainous cities and the main fbnns of special-shaped interchange,and puts forward a reasonable design scheme,hoping to make a smooth development of the special-shaped interchange in mountainous cities.
文摘In order to promote the development of urban roads,enhance urban road design,and fully maximize the role of urban roads,this study first discusses the fundamental requirements of urban road design,the“humanized”concept in urban road design,and the importance of“humanized”urban road design,as well as proposes several“humanized”design strategies for urban roads as references.
文摘Road runoffs were sampled from five highways and five urban roads located in the New Juaben Municipality during the late storm events in the month of November 2014 and the early storm events in January 2015. A variety of water quality parameters such as, pH, temperature, turbidity, electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), aqueous concentrations of Chloride (Cl<sup>-</sup>), Phosphate (), Nitrate () and Sulphate () ions as well as the total concentrations of some selected heavy metals (Fe, Cu, Zn, Pb, Cd, Ni and Cr) were analysed for both periods. Although the results for the studied parameters, particularly the heavy metals varied for both sampling periods, the general trend indicated an increase in accumulation from November 2014 to January 2015. This was attributed to vehicular deposition as well as other natural and anthropogenic depositions on the road surfaces during the antecedent dry weather period between the two sampling months. The highest increase in pollutant loadings was associated with the heavy metals and some physico-chemical parameters such as TSS, TDS, EC and turbidity. Generally, EC, TDS, TSS and turbidity were above the permissible limits of the Environmental Protection Agency (EPA) of Ghana for both sampling periods. However, almost all the mean concentrations of heavy metals recorded for both road runoffs and the control samples were within the permissible limits of the Ghana EPA with some few exceptions.
