Autonomous Vehicle Platoons In Urban Road Networks:A Joint Distributed Reinforcement Learning and Model Predictive Control Approach

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.

Diversity and Application of Herbaceous Flowers in Urban Road Greening in Hefei City

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.

Optimization Strategy of Road Traffic System in Urban Renewal Area

At present,problems such as insufficient road infrastructure and supporting facilities,and limited parking spaces are increasingly prevalent,and there are large conflicts of interest in the process of urban renewal.Therefore,it is crucial to improve the quality of the road network.This paper presents an analysis on the current situation of the road traffic system in a completed area outside the Third Ring Road in Xindu District,Chengdu,and provides corresponding road traffic optimization strategies,with aims of solving the existing road traffic problems,improve road service levels,and promote the overall development of the area and improve the quality of urban space.

Application Strategy of Green Transportation Concept in Urban Road Design

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.

Foliar Particulate Matter Distribution in Urban Road System of Beijing, China

Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is a useful indicator for air PM pollution in road systems. To detect the relationships of foliar PM load with road structures, urbanization, and meteorology in road systems, we studied a widely-planted tree Sophora japonica L. in 100 roads and 10 yards of Beijing, China, and found that the foliar PM loads increased with the distances from the urban centre(DUC) linearly, while decreased with the road density. All-subsets regression analysis indicated that DUC, average monthly relative humidity, average monthly wind speed, and mean annual wind speed were the most important factors in predicting foliar PM load, rather than general situation of buildings and road cleanliness. The monthly relative humidity and monthly wind speed had a negative correlation to foliar PM, while the annual relative humidity and annual wind speed had a positive correlation to foliar PM. Suburban areas and these effective factors should be highlighted in PM control in Beijing.

Automatic Extraction of Urban Road Centerlines from High-Resolution Satellite Imagery Using Automatic Thresholding and Morphological Operation Method

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.

Microclimate Regulation of Urban Road Landscapes and PM 2.5 Control Measures

This paper proposed through systematic analysis that road tail gas is an important source of PM2.5,and elaborated the infl uence of urban road space forms and road landscapes on urban microclimate,on the basis of which gave corresponding landscape design suggestions for PM2.5 control.

The Effects of Road and Other Pavement Materials on Urban Heat Island (A Case Study of Port Harcourt City)

Urban centers are consistently exhibiting higher temperature than its surrounding suburban rural areas. The large amount of heat generated from urban structures such as road materials and pavement materials and other anthropogenic heat sources are the main causes of Urban Heat Island (UHI). The sources of data for this research included primary and secondary sources. Other techniques employed for data collection were direct measurement and readings on the road and pavement materials. The research found out that, there was consistency in rising temperature at different time of the day by the different road and pavement materials. Asphalt has the greatest effect of increasing the urban temperature four degrees higher, followed by concrete, three degree rise in temperature, and earth (ordinary ground) by two degree rise and vegetation (grass) by one degree rise in temperature. The overall effect on the residents of the study area ranges from increase in hotness of the day;44.6% respondents agrees;while 34.3% says it affects the ambient air quality of the area, and other effects such as increased ground level ozone, suffocation, sleeplessness and restlessness as a result of excessive high temperature especially at night are identified in this paper. The research recommends the review or redesigning of the entire Port Harcourt city Master Plan to make provision for creation of more green areas rather than pavements and concreted areas to reduce the effects of (UHI) and ultimately improve the comfort and living conditions of the people in a the garden city Port Harcourt.

Traffic Organization Optimization of Urban Road Combined Intersections

With the development of the economy and the acceleration of urbanization, the number of vehicles in cities is increasing rapidly, which greatly increases the pressure on urban traffic. Solving traffic accidents and problems to keep smooth travel and safe travel has become a top priority in road construction. In this paper, how to optimize the traffic at the intersection of the urban road was discussed with the aim of reducing traffic accidents and problems to keep peoples’ smooth travel and safe travel.

A GIS-based Spatial Analysis of Housing Price and Road Density in Proximity to Urban Lakes in Wuhan City, China

As one of the essential urban open spaces, lakes usually contribute immensely to the quality of residents′ daily lives. Different from hedonic approach employed in existing researches on urban open spaces in China, this paper integrates housing price surface with road density to analyze the spatial characteristics in proximity to urban lakes in Wuhan City, China. With the expansion of Wuhan City, urban lakes became polluted, they shrunk or even disappeared, leading to unfavorable conditions for sustainable development of the city. To better understand the spatial relationship between the city and lakes, we classify the urban lakes in Wuhan central area into ′lakes in the urban center′ and ′lakes in urban fringe′. Based on housing price surface we explore the spatial characteristics in proximity to different lakes and differences between the lakes. We also use Geographic Information System(GIS) tool to calculate road density as a supplementary indicator to reflect the accessibility in proximity to urban lakes. The results indicate that relative independence exists between different towns, and the spatial characteristics are different depending on scales and locations. In most of cases, the road density is lower where closer to the lakeshore while the housing price exhibits an opposite pattern. We conclude that city governments and urban planners should give more considerations to these spatial differences, somewhere should be better planned and protected as an important waterfront and somewhere the control of unreasonable real estate development nearby should be strengthened.

Relationship Between Urban Road Traffic Characteristics and Road Grade Based on a Time Series Clustering Model： A Case Study in Nanjing, China

With the increasing number of vehicles in large-and medium-sized cities challenges in urban traffic management, control, and road planning are being faced. Taxi GPS trajectory data is a novel data source that can be used to study the potential dynamic traffic characteristics of urban roads, and thus identify locations that show a notable lack of road planning. Considering that road traffic characteristics on their own are insufficient for a comprehensive understanding of urban traffic, we develop a road traffic characteristic time series clustering model to analyze the relationship between urban road traffic characteristics and road grade based on existing taxi trajectory data. We select the main urban area of Nanjing as our study area and use the taxi trajectory data of a single month for evaluating our method. The experiments show that the clustering model exhibit good performance and can be successfully used for road traffic characteristic classification. Moreover, we analyze the correlation between traffic characteristics and road grade to identify road segments with planning designs that do not match the actual traffic demands.

Road transport and urban air quality in China

This paper takes a comprehensive view at transportationrelated air pollution problems and solution options. While the transport infrastructure in major Chinese cities is briefed, the environmental impacts of transport activities on urban air quality are discussed in detail. Not only the contribution of automotive emissions to the CO, NMHC and NO\-x pollution in urban areas is reviewed, but also concerns over the carcinogenic emissions, lead deposition and noise are presented. From a lifecycle view point, the impacts of motorway construction, as well as those from scrapped cars, car batteries and old tires in China have been taken into account. In the second part of this paper, the current technical efforts to curb vehicular emissions are evaluated. The performances of unleaded petrol, domestic catalytic converters, and fuel injection systems have been assessed. Options of cleaner alternative fuels and “green” vehicles are discussed, with both the life-cycle impacts and economic feasibility emphasized. Policy and management aspects for effective pollution control are tackled. In particular, speculations about potential economic incentives and legislative measures for vehicular pollution control are presented.

Express way and Urban Road Interchange Design Strategy

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.

Integrated reliability of travel time and capacity of urban road network under ice and snowfall conditions

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.

Maintenance Measures of Urban Road Landscaping

Functions of urban road greening were analyzed firstly,and then problems in the maintenance of urban road greening were discussed. Finally,measures to strengthen the maintenance of urban road greening were put forward,such as strictly controlling design and construction,strengthening greening supervision,enhancing greening maintenance and management and improving maintenance measures,and strengthening the prevention and control of pests and diseases in road greening.

Urban avifauna distribution explained by road noise in an Eastern European city

In Eastern Europe,efforts are being made for road infrastructure development,as this area has not yet reached the level of that in the West.Road noise negatively affects birds,especially in urban habitats.Therefore,seven green spaces from an Eastern European city were monitored,which were selected according to the urbanization gradient and the hydrographic peculiarities of the area.The correlation between species richness and human population density,urban mobility,or road noise was verified.These three factors together explained over 99%of species richness distribution in habitats and during study periods.Road noise was the strongest predictor and the most negative influencer of bird species.These correlations were higher when we also considered the variability of species in habitats over time,instead of the total species richness of a habitat,as it expresses more accurately the impact of noise on the presence of species.The presence of species has decreased from one habitat to another along the urbanization gradient,from the edge of the city to the center,both in the case of terrestrial and aquatic green spaces.The most central park differed significantly from the other terrestrial green spaces in the city.At the same time,no significant differences were registered between the aquatic habitats or the rest of the terrestrial habitats.The ideal mitigation measure in this case would be that there are no roads in the immediate vicinity of green spaces.Still,if this is not possible(as in the case of all the existing green spaces in a city),we discuss/recommend placing noise barriers at the edge of green spaces or high-speed roads.

Traffic Signals Control with Adaptive Fuzzy Controller in Urban Road Network

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.

An Evaluation of Measures Regarding Road Traffic against the Urban Heat Island in the Tokyo Ward Area, Japan

This study aims to evaluate measures against the Urban Heat Island (UHI) regarding artificial exhaust heat of road traffic using Geographic Information Systems (GIS) in the Tokyo Ward Area where the degree of UHI is particularly strong. We developed a GIS database that reflected road traffic conditions, and calculated the volume of artificial exhaust heat of road traffic to evaluate measures against the UHI. The findings of this study can be summarized in the following three points. 1) Artificial exhaust heat volume for moving targets was remarkably higher than that of stationary targets and, in particular, artificial exhaust heat volume was high on roads with remarkable numbers of vehicles and running speeds such as expressways and ring roads. 2) In UHI- related policy for moving targets, the suppression of waste heat through choice of fuel burned, improvement of traffic flow by securing space for cyclists and pedestrians, development of bypasses, and upgrading signal control managed to reduce artificial exhaust heat volume, even though there were differences in degree of reduction. 3) In UHI-related policy for stationary targets, special road surfaces and the increase in efficiency of energy consumption equipment achieved a reduction ratio of around 30% in artificial exhaust heat volume, more than moving targets as well as making it possible to expect a reduction in artificial exhaust heat volume on a wide scale.

Appraisal of Urban Road Traffic Noise in tier-II City(Surat City),India

Urban road traffic noise pollution has always been identified as a severe problem that affects urban populants.In developing nation,road traffic noise pollution depends on the composition of heterogeneous traffic composition.These traffic compositions contain vehicles,which have different sizes,speeds variations,a different dimension of vehicles.Environmental noise measurements have been carried out during day-time and night-time in different locations of tier-II city of India.The noise levels have been continuously measured over 24 h periods using kimo DB 300 class-2 noise level meter.The data contained in this research paper represent 768 measurement hours.All the information has been used to investigate the time patterns of the noise levels under a wide range of different conditions and to study the relationships between noise levels and traffic in urban areas.Maximum LAeq was observed 73.3 dB(A)at B_(14) location and the minimum was recorded 65.7 dB(A)at C_(3) location,which was greater than the central pollution control board(CPCB)prescribed limits during night time.A major reason for the generation of road traffic noise is due to the equal composition of 2-wheeler and 4-wheeler on the arterial road and heavy vehicles were recorded during morning peak and evening peak even though they are prohibited during peak hours.