Congestion In Urban Areas Research Articles

DyETC: Dynamic Electronic Toll Collection for Traffic Congestion Alleviation

To alleviate traffic congestion in urban areas, electronic toll collection (ETC) systems are deployed all over the world. Despite the merits, tolls are usually pre-determined and fixed from day to day, which fail to consider traffic dynamics and thus have limited regulation effect when traffic conditions are abnormal. In this paper, we propose a novel dynamic ETC (DyETC) scheme which adjusts tolls to traffic conditions in realtime. The DyETC problem is formulated as a Markov decision process (MDP), the solution of which is very challenging due to its 1) multi-dimensional state space, 2) multi-dimensional, continuous and bounded action space, and 3) time-dependent state and action values. Due to the complexity of the formulated MDP, existing methods cannot be applied to our problem. Therefore, we develop a novel algorithm, PG-beta, which makes three improvements to traditional policy gradient method by proposing 1) time-dependent value and policy functions, 2) Beta distribution policy function and 3) state abstraction. Experimental results show that, compared with existing ETC schemes, DyETC increases traffic volume by around 8%, and reduces travel time by around 14:6% during rush hour. Considering the total traffic volume in a traffic network, this contributes to a substantial increase to social welfare.

Analysis of telecommuting behavior and impacts on travel demand and the environment

The discussion of whether, and to what extent, telecommuting can curb congestion in urban areas has spanned more than three decades. This study develops an integrated framework to provide the empirical evidence of the potential impacts of home-based telecommuting on travel behavior, network congestion, and air quality. In the first step, we estimate a telecommuting adoption model using a zero-inflated hierarchical ordered probit model to determine the factors associated with workers’ propensity to adopt telecommuting. Second, we implement the estimated model in the POLARIS activity-based framework to simulate the potential changes in workers’ activity-travel patterns and network congestion. Third, the MOVES mobile source emission simulator and Autonomie vehicle energy simulator are used to estimate the potential changes in vehicular emissions and fuel use in the network as a result of this policy. Different policy adoption scenarios are then tested in the proposed integrated platform. We found that compared to the current baseline situation where almost 12% of workers in Chicago region have flexible working time schedule, in the case when 50% of workers have flexible working time, telecommuting can reduce total daily vehicle miles traveled (VMT) and vehicle hours traveled (VHT) up to 0.69% and 2.09%, respectively. Considering the same comparison settings, this policy has the potential to reduce greenhouse gas and particulate matter emissions by up to 0.71% and 1.14%, respectively. In summary, our results endorse the fact that telecommuting policy has the potential to reduce network congestion and vehicular emissions specifically during rush hours.

A Study on the Restructuring and Cavitation of the Data-based Pick-up and Delivery Business

The recent rapid growth of the parcel delivery market has led to a rapid increase in the volume of traffic in urban logistics centers. Excessive competition among courier companies and a lack of logistics infrastructure in urban areas have seriously reduced service quality and profitability and have led to traffic congestion in urban areas as well as environmental problems. This study develops a model for integrating services among more than two courier companies for the same service area by proposing a way to design and assign routes for luggage delivery to each participating company. We verify the results of the proposed integration and cooperative operation model by comparing performance indicators (including total cost) between two routing approaches, the dynamic and fixed models, based on the demand pattern. The proposed model may enable a reduction in traffic congestion and environmental problems caused by courier services in urban areas. It may also address the profitability problem caused by the overheated competition in the courier business.

The effect of noise on the comfort of passengers inside the tramway and its impact on traffic congestion in the urban area

The tramway is a mean of transport which is used frequently in many cities around the world, because it improves the offer of public transport through its important capacity of transporting. This may ameliorate the state of road traffic by reducing the number of vehicles along the tram line. Despite these advantages, there are some problems related to users’ comfort like the noise caused during the operation. This study is focused on the human perception of the noise levels detected inside the tramway. The objective of this work is to identify and analyze the level of noise detected inside tramway, to know in which cabin and section the high noise is recorded, to find the causes and to show if the measured noise influences the comfort of passengers. For that, noise measurements are taken in all cabs and along the tram line. The results show that the levels of noise inside the seven cabins is different. The high noise is detected in the motorized cabins and in many sections, like the curves and also in other sections. The results show also that this noise affects negatively on the comfort of passengers. Finally, different solutions that can contribute to reduce effectively the noise to make the tram more comfortable and efficient to relieve traffic congestion in urban areas are presented.

Determining factors for levels of volatile organic compounds measured in different microenvironments of a heavy traffic urban area

The levels of BTEX (benzene, toluene, ethylbenzene and xylenes) in a congested urban area of Hanoi were characterized in a winter and a transitional period in 2015. Monitoring was conducted at two roads simultaneously with traffic flows and one ambient site together with meteorology. Hourly and bi-hourly BTEX samples collected using charcoal tubes were analyzed by GC-FID. BTEX levels in winter, 131 ± 71 μg/m3 in heavy traffic Truong Chinh (TC) road, 101 ± 29 μg/m3 in small residential Nguyen Ngoc Nai (NN) road, and 30 ± 15 μg/m3 in the ambient air site (AA, about 150 m from each road) were 1.3–2.1 times higher than the respective levels in the transitional period. Hourly benzene levels exceeded the Vietnam national standard more frequently at TC (45%) than at NN (32%) and least at AA (5%) out of 120–180 measurements, respectively. Roadside hourly levels well reflected the diurnal traffic flow pattern and higher BTEX levels were measured at TC than NN. The ambient site exhibited lower BTEX levels and different diurnal patterns, with more pronounced evening peaks than morning rush hour peaks. BTEX pollution rose showed a strong influence of wind to levels measured at AA. Species ratios (T/B and X/E) showed typical ranges for traffic emissions at roadsides. Ratios for AA and NN after midnight with no vehicles operating showed the aging effects with typical low X/E ratios. Multivariate analysis results suggested association of gasoline vehicles with BTEX at roadsides. Backward trajectory analysis indicated potential regional transport of long-lived benzene associated with continental airmass categories. BTEX at TC our study were 2–3 times lower for every species compared to those previously reported, showing results of fuel quality and vehicle technologies improvement. Health risks of people working at the roadside also reduced by about 3 times during the 10 years.

Selection of support system for urban deep excavations: A case study in Ahvaz geology

Today, the increased need for construction in congested urban areas has necessitated construction of tall and massive structures. In these cases, design engineers have the option of excavation and digging of undisturbed and fresh spaces under the ground. Due to the presence of urban structures and public facilities adjacent to the excavation sites, which in some cases are highly important, the use of a support system with good and safe performance that can prevent probable losses is essential. Therefore, various support systems can be proposed for stabilizing the excavations and their surroundings. Nevertheless, selecting an appropriate support system in urban areas that can increase the stability of excavations has been a long-time challenge for design engineers. Due to the variable geotechnical conditions in these areas, which occasionally cause extensive changes between soil layers within a close distance, the stress-deformation field is very complicated and extended, making it difficult to select and design a proper and safe support system. Therefore, in this study, after investigating different excavation methods in urban areas and comparing conventional and widely used methods in these areas, an appropriate and safe support system was proposed for excavation in urban areas depending on construction, structural and economic conditions. The behavior of a controlled excavation using the proposed support system in Ahvaz city which possesses variable and complex geotechnical properties, was investigated, and the displacement values during the construction and the progress of the excavation were examined and assessed. For a more precise investigation of the support system behavior, the performance of the support system was compared with other systems utilized in other projects in Ahvaz city. The obtained results indicated that application of a rigid system would have the best performance.

Causes of traffic congestion in urban areas. Case of Poland

The dynamic development of urban areas poses increasingly more challenges for the provision of transport services for the population. The concentration of the economic potential and population in the metropolitan areas results in the occurrence of large transport needs, and when these needs are met at the same time, the phenomenon of congestion occurs. The purpose of the article is to research the relationship between various factors contributing to congestion in urban traffic and the level of congestion in Polish cities. The authors have used statistical methods such as correlation and regression analysis. The research has shown that the most statistically significant relationships have occurred in the case of the number of business entities and the number of passenger cars. It can be concluded that the demand side factors are more important in Polish cities than the supply side factors or perhaps the current transport policy is ineffective. When effectively applied, transport policy instruments can play a special role. These instruments can contribute to reducing congestion in various ways, i.e. by implementing various sub-objectives, which include reducing the need to travel, reducing the use of passenger cars, improving the functioning of public transport and use of the infrastructure. The results of this study can be useful for transport policy makers at central, regional and local levels.

Numerical analysis of framed building response to tunnelling induced ground movements

Tunnelling in congested urban area may inevitably induce ground movement causing damage to adjacent surface buildings. Past research usually oversimplified surface structure as an equivalent elastic beam, which is unable to represent behaviour of a framed building realistically due to frame action. In this study, a series of numerical analyses were conducted to investigate the behaviour and damage mechanism of a framed building with individual footing due to tunnelling induced ground movements. Nonlinear behaviour of the infilled wall and the interfaces between soil-structure and between frame-wall were explored to interpret the complex interaction effects in the system. A non-uniform deformation around the tunnel was applied to simulate the realistic tunnelling induced ground movements while the distribution of initial ground stiffness affected by building weight was reproduced by a user defined nonlinear constitutive model. The different responses in terms of angular distortion, horizontal strain and smeared crack pattern of the framed building subject to scenarios with different ground stiffness, interface parameters and different frame infill configurations were evaluated. The results can be practically used to assess the performance of framed building subject to different ground deformation conditions resulting from tunnelling. The presented analysis provided a useful background for properly understanding and prioritizing those factors having a significant effect on the response of framed building to tunnelling induced ground movements.

Earth pressure on shield excavation face for pipe jacking considering arching effect

Pipe jacking is often used to install pipelines in congested urban areas or river crossings. The applied jacking force needs to be greater than the frictional resistance along the pipe and the face resistance. Lubricant slurries are usually employed to minimize the frictional resistance. Therefore, it is critical to estimate earth pressures acting on shield excavation face correctly. In this paper, the original Protodyakonov’s arch model is modified to calculate the vertical pressure on deeply buried pipes. For shallow burial depth less than 5 m, the Terzaghi arching model is still applicable to estimate the vertical pressure. The soil prism in front of excavation face is divided into different zones to establish the force equilibrium. The calculated earth pressure is applied on top of soil wedges. The proposed analytical solution can analyze the stability of vertical and inclined excavation faces considering the influence of three-dimensional arching effect, as well as the contribution of soil cohesion. In the end, the effectiveness of the developed design framework is assessed by comparing calculations with experimental measurements of earth pressures on excavation face.

Investigation of terrain effects on the consequence distance of CO2 released from high-pressure pipelines

As part of Carbon Capture and Storage (CCS) projects, Carbon Dioxide (CO2) is usually transported via pipelines from source to sequestration location. Ensuring the safety of the operation is of great importance, as CO2 is a hazardous substance and an accidental release may have catastrophic consequences. Therefore, a comprehensive understanding of the effects of a CO2 release from CCS facilities is essential to allow the appropriate safety precautions to be taken. The majority of prior studies that address this topic do so by simulating CO2 dispersion over a flat horizontal terrain. However, CO2 pipelines may be deployed near topographically complex locations such as congested industrial or urban areas. The extent to which the complexity of the terrain may affect the area affected by an accidental release has not been explored in detail. In this paper, we present Computational Fluid Dynamics (CFD) models for the prediction of atmospheric dispersion of CO2 over complex terrains, in order to evaluate the ‘consequence distance’ relating to accidental CO2 releases from high-pressure pipelines. The CFD model is validated against the results of a heavy gas dispersion experiment carried out at Thorney Island. Simulations of CO2 dispersion over seven types of complex terrain are carried out, considering ‘full-bore’ rupture of a pipeline carrying a pre-combustion CO2 mixture. The influence of different terrain features on the consequence distance is studied. In addition, the dispersion of a (CO2+H2S) mixture is simulated to investigate the threshold value of the fraction of Hydrogen Sulphide (H2S) for which the hazardous effects of H2S become significant for a release over complex terrains.

Monitoring traffic congestion in urban areas through probe vehicles: A case study analysis

We present a probe vehicles approach to evaluate traffic congestion in urban areas. The method is illustrated by a real case study in Bari, Italy. Global Positioning System (GPS) data generated by buses are transmitted via General Packet Radio Service (GPRS) to a control station, where they are used to analyze traffic conditions. Traffic indices are evaluated to provide an exhaustive view of roads congestion and implement suitable control strategies. Thus, traffic administrators can efficiently manage sustainable mobility in cities and people can acquire awareness on traffic and public transport performance.

16.26: Design and construction of composite bridges

ABSTRACTComposite bridges, where steel girders are used compositely with a concrete deck slab, can be preferred over steel or concrete bridges due several reasons. They are less expensive and require less maintenance than orthotropic steel decks and they are lighter than concrete girders. They often require less temporary structures for execution and by using prefabricated elements fast erection can be achieved. Composite bridges are often chosen for span ranges that are in between the typical span ranges of concrete and steel bridges.When designing a composite bridge deck it is important to carefully consider the different material characteristics of steel and concrete to achieve an optimum design both in respect of erection sequence and material quantities. The concrete slab has a high resistance to compression forces whereas steel is prone to buckling, but has a high tension capacity.The Constantine ramp bridges (Algeria, 2014) are open steel box girders with a filigran concrete slab. They are located on steep slopes in a congested urban area, which gave limitations to the construction methods. A composite deck solution was chosen so that steel segments could first be lifted into place by a medium size crane and secondly prefabricated concrete slab filigran members could be placed on the steel and used as formwork for the final in situ casting of the concrete slab. The construction sequence was planned so that the concrete slab would be mainly in compression in the dead load situation to optimize material quantities.Composite bridge decks are often applied in cable stayed bridges, since the concrete slab has good abilities to resist the high compression induced by the inclined cable stays particularly near the towers. Examples of recent composite cable stay bridges are Busan Bridges (Korea 2014, main span 475 m) and New NY Bridge (New York, under construction, main span 366 m) where bolted wide flange steel girders were used in combination with a concrete slab and Sungai Johor Bridge (Malaysia 2013, main span 500 m) where an open box section was applied.Composite bridge decks are often used in combination with all steel or all concrete decks to balance the weight when for example the main span is very large compared to the back spans such as for the Stonecutters bridge (Hong Kong, 2009, Main Span 1018m).

A stochastic optimization framework for road traffic controls based on evolutionary algorithms and traffic simulation

Traffic flow is considered as a stochastic process in road traffic modeling. Computer simulation is a widely used tool to represent traffic system in engineering applications. The increased traffic congestion in urban areas and their impacts require more efficient controls and management. While the effectiveness of control schemes highly depends on accurate traffic model and appropriate control settings, optimization techniques play a central role for determining the control parameters in traffic planning and management applications. However, there is still a lack of research effort on the scientific computing framework for optimizing traffic control and operations and facilitating real planning and management applications. To this end, the present study proposes a model-based optimization framework to integrate essential components for solving road traffic control problems in general. In particular, the framework is based on traffic simulation models, while the solution needs extensive computation during the engineering optimization process. In this work, an advanced genetic algorithm, extended by an external archive for storing globally elite genes, governs the computing framework, and in application it is further enhanced by a sampling approach for initial population and utilizations of adaptive crossover and mutation probabilities. The final algorithm shows superior performance than the ordinary genetic algorithm because of the reduced number of fitness function evaluations in engineering applications. To evaluate the optimization algorithm and validate the whole software framework, this paper illustrates a detailed application for optimization of traffic light controls. The study optimizes a simple road network of two intersections in Stockholm to demonstrate the model-based optimization processes as well as to evaluate the presented algorithm and software performance.

Decongestion of Urban Areas with Hotspot Pricing

The rapid growth of population in urban areas is jeopardizing the mobility and air quality worldwide. One of the most notable problems arising is that of traffic congestion which in turn affects air pollution. With the advent of technologies able to sense real-time data about cities, and its public distribution for analysis, we are in place to forecast scenarios valuable to ameliorate and control congestion. Here, we analyze a local congestion pricing scheme, hotspot pricing, that surcharges vehicles traversing congested junctions. The proposed tax is computed from the estimation of the evolution of congestion at local level, and the expected response of users to the tax (elasticity). Results on cities' road networks, considering real-traffic data, show that the proposed hotspot pricing scheme would be more effective than current mechanisms to decongest urban areas, and paves the way towards sustainable congestion in urban areas.

Evaluation of pedestrian wind comfort near ‘lift-up’ buildings with different aspect ratios and central core modifications

Owing to the void space at lower heights, lift-up buildings have high building permeability at ground level and subsequently improve the air circulation in congested urban areas. Despite this advantage, the lift-up design has been sparsely adopted for buildings in urban areas partly because of the lack of understanding of the combined effects of building dimensions and lift-up design on the surrounding pedestrian level wind (PLW) field. Therefore, this study aims to investigate the influence of lift-up buildings with different aspect ratios (height/width) on the surrounding PLW field and pedestrian wind comfort level. Five lift-up buildings with aspect ratios 4:1 to 0.5:1 were tested in a boundary layer wind tunnel and results were compared with those of five buildings with similar dimensions but without lift-up design. The results reveal a strong dependence of the maximum wind speed in lift-up areas with building height, which results subsequently a small area of acceptable wind conditions near tall and slender lift-up buildings. Lift-up designs adopted for short and wide buildings produce larger areas of pedestrian wind comfort. The central cores modified with corner modifications are effective in increasing the pedestrian wind comfort in the lift-up area of tall and slender buildings.

Optimization of park-and-ride system: A case study of Shunyi in Beijing

Nowadays, rapid increase in automobile ownership results in traffic congestions especially in large cities all over the world. Park-and-ride mode could ease traffic congestion in urban areas without abandoning traffic demands. The optimization of park-and-ride facility location and charging rules are of importance for travelers, governments, and environment. Therefore, a multi-objective model considering investments and pollution is proposed and a bi-level genetic algorithm is designed. The case study of Shunyi in Beijing is conducted and the results show that the optimization model is feasible, which could provide suggestion for charging policies and park-and-ride locations.

Classification and benchmark of City Logistics measures: an empirical analysis

ABSTRACTUrban freight distribution accounts for a significant share of pollution and congestion in urban areas. To reduce these negative impacts, municipalities have implemented several City Logistics (CL) measures. This paper presents the empirical analysis of a dataset of 70 European cities that have been piloting or rolling out a CL measure, to provide an updated indication of the status of CL initiatives and analyse the diffusion of CL internationally. The research objective is also to help understand the contextual factors might explain their introduction. To this end, a set of City Logistics Indices (CLI) is used as indicators of the breadth and number of CL measures implemented in a city. A statistical correlation of these CLIs with respect to a set of independent variables, namely the contextual factors, is also performed. Results reveal that the level of pollution, the diffusion of e-commerce and GDP are important drivers of CL deployment.

Improving pedestrian facilities in congested urban areas: a case study of Chennai city

Traffic congestion and lack of public pedestrian space are some problems faced by most urban metropolises. Conventionally walking has been a mode of transportation in Indian cities. The percentage of pedestrians may vary from 16 to 57 depending upon the city. Encounters between vehicular traffic and pedestrian traffic are at its rise currently. Rapid industrialization and urbanization in India has resulted in neglecting of pedestrian facilities. Consequently pedestrian are at greater risk for their safety more especially in the commercial zones of large cities. A change in perspective spotlight will create a sense of awareness that the pedestrian traffic is also vital as the vehicular traffic. Soothing the traffic would moderately cut the driving expediency but the pedestrians will get a much safer and peaceful route to their terminuses. Safety and comfort are the two pans of a balance while considering the pedestrian traffic. Considering these aspects, this study deals a study in improving pedestrian facilities by analysing the existing skeleton of the selected locations. The adequacy of facility is checked based on IRC latest guidelines and counteractive measures are postulated.

The Influence of New Information Technologies in Supply Chains Logistics on Mobility in Urban Areas

Cities are places of countless logistics processes, i.e. the processes of flow of all kinds of resources: human, material, information. The basic problem of contemporary cities are factors limiting their sustainable development. Most of them originate from excessive congestion caused by individual motorization and road freight transport. In recent years, supply chains intensively develop and implement new information technologies. That aims at rationalizing the business logistics processes by improving the information flows which is followed by reducing the demand for physical resources and the reduction of processing time and costs. Because the cities are large areas of logistics processes related to the economic activities of enterprises, the purpose of this article is to answer the following question: how do new information technologies, used in logistics processes, influence the structure of resources mobility in urban areas and how they can help in solving problems of congestion in urban areas. The main assumption of the study is that information flows can partially substitute real flows, which leads to the main thesis of the research that new technologies which streamline the flows of information in B2B and B2C relation can reduce the demand for goods and human flows within the cities. That rationalization translates into changes of resources demand structure and thus a change in demand for their mobility. The study used analysis and deduction method based on the literature and real life examples in the field of information technology which are already in use and those that can be used soon in logistics processes. This field of research is underdeveloped because logisticians focus their research on economization of business logistics processes and do not pay much attention to how they can influence urban areas.

Zoned and staged construction of an underground complex in Shanghai soft clay

Construction of an underground complex in congested urban areas calls for excavation of a group of foundation pits, referred to as a pit complex, which are usually surrounded by existing facilities. In such circumstances, the safety of the pit complex and facilities during the construction are of great concern. This paper presents a case of an underground complex construction in Shanghai soft clay. A pit complex composed of two deep excavations was excavated for a Comprehensive Transport Hub (CTH) and a commercial retail area and pedestrian concourse known as South Square (SS), which were connected to an operating metro station and a railway station. During the excavation, potential deformation of metro tracks and railway tracks were expected due to extensive soil unloading. To safeguard the railway and the subway, a zoned and staged construction technology was proposed, in which several temporary partition walls were constructed in addition to necessary supporting structures, to allow the large-scale deep excavations to be divided into several independent small-scale excavations. This paper discusses the rational construction sequence of these excavations as well as reinforcement measures in detail. The construction technology was examined by extensive field data. It is found that the maximum horizontal displacement of diaphragm walls ranged between 0.05% He and 0.4% He, where He is the excavation depth. The vertical displacements of the railway tracks were well controlled, whereas the metro tracks heaved significantly due to unloading effect.