Congestion In Urban Areas Research Articles

Freenet: Spectrum and energy harvesting wireless networks

The dramatic growth in mobile data traffic is resulting in spectrum crunch, and is also leading to exorbitant energy consumption. Thus, it is desirable to liberate mobile and wireless networks from the constraint of spectrum scarcity and to rein in growing energy consumption. This article introduces FreeNet, figuratively synonymous with “Free Network,” which engineers spectrum and energy harvesting techniques to alleviate spectrum and energy constraints by sensing and harvesting spare spectrum for data communications and utilizing renewable energy as power supplies, respectively. Hence, FreeNet increases the spectrum and energy efficiency of wireless networks and enhances network availability. As a result, FreeNet can be deployed to alleviate network congestion in urban areas, provision broadband services in rural areas, and upgrade emergency communication capacity. This article provides a brief analysis of the design of FreeNet that accommodates the dynamics of the spare spectrum and employs renewable energy.

Evaluation, Classification, and Influential Factors Analysis of Traffic Congestion in Chinese Cities Using the Online Map Data

This study proposes a new method to describe, compare, and classify the traffic congestion states in 23 Chinese cities using the online map data and further reveals the influential factors that may affect them. First, the real-time traffic congestion information is obtained from the online map of AutoNavi in a 15-minute interval. Next, a new measuring index is introduced to describe the overall characterization of congestion patterns in each city based on online map data, which is named as the congestion ratio. The next analysis is the cluster analysis based on the temporal distribution of the congestion ratio, which helps to identify groups of the selected cities with similar traffic congestion states. These cities are categorized as four groups according to the severity of traffic congestion: severely congested, less severely congested, amble, and smooth cities. Lastly, multiple linear regression models are developed to identify the primary factors that affect the congestion ratio. The result shows that the influences of per capita road area, car ownership, and vehicle miles traveled (VMT) on the congestion ratio are significant. Sensitivity analyses are also implemented in order to reveal more effective policy measures in mitigating traffic congestion in urban areas.

Work Zone Management in the District of Columbia: Deploying a Citywide Transportation Management Plan and Work Zone Project Management System

In a growing and congested capital city, the challenges of maintaining traffic during construction of a multimillion dollar transportation program are immense. Managers are tasked with budgeting, planning, designing, procuring, constructing, and monitoring hundreds of projects in a dynamic and politically charged environment. Critically important infrastructure, utility, maintenance, and developer projects—as well as capital area special events—are frequently on a national (or international) stage with a high risk of traffic congestion, safety concerns, and negative public perception. Washington, D.C., is often listed as one of the top 10 tourist destinations in the United States. With a growing resident population, commuters nearly double the number of people in the city each weekday. In addition, Washington, D.C., is often listed as the most congested urban area in the nation. Aside from recurring congestion, project construction and special events frequently strain the existing roadway network. A proactive, citywide approach to managing all work zones is helping to reduce congestion and provide the District Department of Transportation with better control of how best to schedule and approve projects, as well as budget for cost-effective strategies to mitigate work zone congestion. A unique Citywide Transportation Management Plan, including a dynamic Work Zone Project Management System, has been deployed to coordinate and analyze project work zones and special events throughout the city for the next 5 years. Graphical, web-based software tools track and assess cumulative work zone effects. From these results, mitigation strategies are aimed at improving safety and mobility throughout Washington, D.C.

METRO.FREIGHT.2020 – Strategies for Strengthening Rail Infrastructure for Freight Transport in Urban Regions

In most European congested urban areas the rail tracks of the 19th and 20th century serving locations of industry and goods stations were removed, transformed for public passenger transport, closed down or used for other purposes. The main reasons might be the de-industrialisation of the inner cities and the centralisation of the supply-sector (wholesale markets, shopping centres). Simultaneous the urban areas got an excellent road network on the surface and an efficient public transport system in the underground or on dedicated tracks. Nevertheless the amount of goods delivered to urban areas increased due to material prosperity.In this context “METRO.FREIGHT.2020” analysed the possibilities of a reinforced utilisation of railway infrastructure for freight transport on the first and the last miles within the urban regions in Austria as exemplified in case studies for the metropolitan Region of Vienna, the agglomerations of Graz and Linz and for the urbanised Rhine-Valley in Vorarlberg. In this context the focus point of consideration was the interface of transport and urban development, to a lesser extent the theoretical approach behind. As a fundamental milestone a cadastre of existing or recoverable sidings or other rail shipping points has been surveyed. They were evaluated in respect of serviceability concerning tracking freight trains in the rail network and extensibility in the service area which was complemented with propositions for further developing.The recommendations focus measures intending technically and economically operable access points to rail net on one hand and potentially appropriate access points for the future. But, to reach this goal more strengthened integration of commercial location policy and of shippers’ transport demands with a coordinated land use planning and an infrastructure development policy is required. Finally the methodical approach elaborated comprises following components to push more rail freight shipping:•Traffic zoning is a hierarchical spatial approach subdividing an urban region in sectors, zones and ‘agglomerates’ as spheres of activity for political and private actors involved in freight traffic generation and infrastructure affaires.•Surveying a multimodal topology of infrastructure network which integrates all transport modes in its layout of freight infrastructure propped up on a public platform of a multimodal network graph in future.•Characterizing an ‘agglomerate’ typology of shipping sites with affinity to rail which describes the typical initial position and development trends of the freight transport inducing traffic zones.•Shaping spatial structures which consist of super structures of shipping industrial sites as traffic generators, the infrastructure with its capacity for freight movements and the ‘metastructure’ as external affected settlements and land uses are prime targets and intervention objects, the coordinated measures have to be allocated to.The railway operators are called on to offer more flexible train and operation forms tailored to the logistics of shippers if the rail infrastructure within the serving area from the consolidation node to the sidings enables it.In the end three scenarios have been identified, namely a scenario of ultimate displacement of rail freight service in towns, a retarding scenario which brakes the retreat of rail connected with a change of paradigm in transport and traffic planning leading into an offensive scenario of ‘clean freight mobility’ to revitalize and extend rail freight operations into areas of high consumption.

TRENCHLESS CONSTRUCTION: USES AND POTENTIALS

Infrastructure projects in the United Arab Emirates (UAE) at federal and local levels have been continuously growing. This includes installation, inspection, repair, and replacement of water mains, sewer, storm water, power, and telecommunication networks. Traditionally, these tasks related to underground utilities involve open trenching construction methods resulting in expensive and disruptive operations, particularly in congested urban areas like Dubai and Abu Dhabi cities. To avoid this serious problem, contractors and local municipalities are using trenchless construction in their infrastructure projects. The development of trenchless methods has gained impetus in the construction industry in UAE due to increasing amounts of investment in underground infrastructures that are new, deteriorating, or under capacity. This paper presents the results of a questionnaire survey of trenchless construction methods used by municipalities and contractors in UAE. The survey provides an indication of current and expected future trends in the application of trenchless construction technologies including types of technologies employed and percentage of projects that employed trenchless technologies. The survey results indicate that trenchless technology is gaining increasing popularity among contractors and municipalities across UAE. The survey results also indicate that trenchless technology is gaining increasing popularity among municipal engineers across UAE. The survey also revealed current and likely future growth in utilizing trenchless construction methods and the average expenditures of municipalities in UAE for new construction and for rehabilitation.

A hybrid method for foundation reuse evaluation

This paper aims to provide a simple, multi-level method for engineers to conduct a pre-construction viability assessment for reuse of existing foundations in congested urban areas. As part of this, the first critical assessment is presented for three major foundation reuse evaluation tools in their ability to predict the outcomes of five published case histories. Based on strengths and weaknesses identified in that process, a hybrid system is proposed. This newly proposed, two-staged methodology is aimed to address socio-economic drivers and technical requirements, as well as to promote future reuse where current reuse is not viable. The proposed system was successfully verified by predicting the outcomes of two other, previously published case histories. In that process, the main drivers were recognised, whereas site-specific constraints and concerns were incorporated. Although the robustness and scalability of the method will need further testing, this paper introduces a promising, new, multi-level appr...

Parking space management via dynamic performance-based pricing

In congested urban areas, it remains a pressing challenge to reduce unnecessary vehicle circling for parking while at the same time maximize parking space utilization. In observance of new information technologies that have become readily accessible to drivers and parking agencies, we develop a dynamic non-cooperative bi-level model (i.e. Stackelberg leader–follower game) to set parking prices in real-time for effective parking access and space utilization. The model is expected to fit into an integrated parking pricing and management system, where parking reservations and transactions are facilitated by sensing and informatics infrastructures, that ensures the availability of convenient spaces at equilibrium market prices. It is shown with numerical examples that the proposed dynamic parking pricing model has the potential to virtually eliminate vehicle circling for parking, which results in significant reduction in adverse socioeconomic externalities such as traffic congestion and emissions.

Development of a new hybrid bus for urban public transportation

Nowadays the increasing demand for sustainable mobility has fostered the introduction of innovative propulsion systems also in the public transport sector in order to achieve a significant reduction of pollutant emissions in highly congested urban areas. This paper describes both the design and the optimization of an environmentally friendly hybrid bus (hereafter referred to as “HYBUS”) for urban public transportation.After a preliminary description of the main features of the hybrid architecture, this paper assessed, through numerical simulations, the fuel economy potential of the hybridization in real world driving conditions. The promising results of this first part of the study led to the development of a first prototype.The first prototype of the bus was built by integrating an innovative hybrid propulsion system featuring a plug-in series architecture into the chassis of an old IVECO 490 TURBOCITY. The bus is 12m long and capable to host up to 116 passengers in the original layout. The project relied on a modular approach where the powertrain could be easily customized for size and power, depending on the specific application.The prototype was then extensively tested in the city of Genoa, Italy, an urban context extremely challenging for a hybrid powertrain due to its frequent uphill routes and significant road grades. The outcomes of the test campaign confirmed the simulations forecasts, and fostered additional analysis aimed to optimize the energy management strategy of the hybrid powertrain.Numerical simulations were then used in order to identify more refined energy management strategies capable of further enhancing the fuel economy potential of the hybrid architecture. Consequently, a novel energy management was developed, and virtually tested, to manage the HYBUS in a more effective way. The results demonstrated the interesting potential of such hybrid architecture.

Predictability of road traffic and congestion in urban areas.

Mitigating traffic congestion on urban roads, with paramount importance in urban development and reduction of energy consumption and air pollution, depends on our ability to foresee road usage and traffic conditions pertaining to the collective behavior of drivers, raising a significant question: to what degree is road traffic predictable in urban areas? Here we rely on the precise records of daily vehicle mobility based on GPS positioning device installed in taxis to uncover the potential daily predictability of urban traffic patterns. Using the mapping from the degree of congestion on roads into a time series of symbols and measuring its entropy, we find a relatively high daily predictability of traffic conditions despite the absence of any priori knowledge of drivers' origins and destinations and quite different travel patterns between weekdays and weekends. Moreover, we find a counterintuitive dependence of the predictability on travel speed: the road segment associated with intermediate average travel speed is most difficult to be predicted. We also explore the possibility of recovering the traffic condition of an inaccessible segment from its adjacent segments with respect to limited observability. The highly predictable traffic patterns in spite of the heterogeneity of drivers' behaviors and the variability of their origins and destinations enables development of accurate predictive models for eventually devising practical strategies to mitigate urban road congestion.

GIS-Based Urban Land Use and Traffic Coordination Evaluation System

To relieve the traffic congestion in urban areas, one approach is to modify the current planning scheme based on the balance between traffic supply and demand. Based on the proposed GIS platform, this paper analyzes the interactive relationship between land use and traffic system. Feasibility judgment of planning scheme is implemented based on land attribute, represented by urban floor area ratio and road area ratio. TransCAD based simulation is used to evaluate the planning scheme by traffic flow and the saturation of each link. Comparisons between traffic generation and traffic network capacity, based on a two-dimensional model of Space and Time Consuming Method, is presented to verify the coordination between urban traffic and land use. A real-world case study is implemented to test the efficiency and applicability of the proposed model and computing methods.

Modeling Safety Impacts of Off-Hour Delivery Programs in Urban Areas

Truck travel on urban road networks during daytime can be a major contributor to traffic congestion. A possible approach to relieve traffic congestion in urban areas is shifting a portion of trucks from regular daytime hours to nighttime off-hours. Benefits of this off-hour delivery strategy can be noticeable, but safety impacts need to be investigated. Manhattan, the most densely populated borough of New York City, with a large demand for truck deliveries, was the study area. Truck crashes, traffic volumes, and geometric design features of 256 road segments in Manhattan were collected to develop safety evaluation models. For quantification of the safety impacts of off-hour deliveries, an improved modeling approach was proposed; it involved the use of the multivariate Poisson-lognormal model integrated with measurement errors in truck volumes. The proposed model could address the inherent correlation of specific truck crash types and correct the estimation bias for safety effects of daytime and nighttime truck volumes. A Bayesian approach was employed to estimate the parameters of the proposed model. From the Bayesian posterior distributions, daytime and nighttime truck volumes did not have significantly different effects on either minor or serious crashes. In addition, truck crash counts were estimated with the proposed model under scenarios with different proportions of truck traffic shifted to nighttime. Results showed that off-hour delivery programs were not expected to increase the overall risk of truck-involved crashes significantly. Study findings can give transportation planners and policy makers insight on safety implications and decision making on off-hour deliveries.

El Centro de Diseño de Barcelona

The most characteristic element of the new Barcelona Design Centre is the 35m span, 20m high and 20m wide cantilever projecting over Las Glorias Catalanas square. The construction method used in its execution (cantilevered erection in a congested urban area), so as the characteristics of the bolted steel structure and the way it is anchored to the concrete core walls, employing post-tensioning systems and stud shear connectors, transform this building into a singular structure in the field of construction. At the same time, the specific tests carried out to assess the suitability of the bolted connections, mainly those developed for the characterization of the friction coefficient used in design are of interest, so as the criteria adopted for the design of post-tensioning and shear connection systems used for anchoring the structure to the concrete core of Block 2.

Parking Space Management via Dynamic Performance-based Pricing

In congested urban areas, it remains a pressing challenge to reduce unnecessary vehicle circling for parking while at the same time maximize parking space utilization. In observance of new information technologies that have become readily accessible to drivers and parking agencies, we develop a dynamic non-cooperative bi-level model (i.e. Stackelberg leader-follower game) to set parking prices in real-time for effective parking access and space utilization. The model is expected to fit into an integrated parking pricing and management system, where parking reservations and transactions are facilitated by sensing and informatics infrastructures, that ensures the availability of convenient spaces at equilibrium market prices. It is shown with numerical examples that the proposed dynamic parking pricing model has the potential to virtually eliminate vehicle circling for parking, which results in significant reduction in adverse socioeconomic externalities such as traffic congestion and emissions.

Empirical analysis of pedestrian delay models at urban intersections

Signalized crosswalks are useful pedestrian facilities but complexities in geometry and configuration arise, especially in congested urban areas, directly affecting safety, cycle length and delay. Universal design criteria are not dealt with by manuals. Scientific literature has proven that pedestrians look for the shortest path at crosswalks, sometimes even adopting unsafe behaviour. On the other hand, drivers’ habits are scarcely bothered by pedestrian signage. The analysis of pedestrians’ cognitive path and choices is fundamental as well as the prediction of irresponsible actions. Delay is a widely adopted parameter to assess pedestrian Level of Service. In this work, a comparison among renowned models to estimate pedestrian delay at signalized crosswalk is set and double-checked with a field study in the city of Bologna – Italy.

Post-Disaster Urban Recovery Monitoring in Pisco After the 2007 Peru Earthquake Using Satellite Image

Pisco was the area most damaged by the 2007 Peru earthquake. The purpose of this research is to develop possibilities of using satellite imagery to monitor postdisaster urban recovery processes, focusing on the urban change in Pisco between 2007 and 2011. To this end, the authors carried out field surveys in the city in 2012 and 2013 and also examined previous surveys to determine that building reconstruction peaked between 2008 and 2009. After analyzing the five-year recovery process, the authors compared its reconstruction conditions by visual interpretation with those by image analysis using satellite image. An accuracy of 71.2% was achieved for the visual interpretation results in congested urban areas, and that for developed districts was about 60%. The result shows that satellite imagery can be a useful tool for monitoring and understanding post-disaster urban recovery processes in the areas in which conducting long-term field survey is difficult.

Empirical analysis of heterogeneous traffic flow and calibration of porous flow model

Heterogeneous traffic flow, characterized by a free inter-lane exchange, has become an important issue in addressing congestion in urban areas. It is of particular interest in many developing countries, that experience a strong increase in motorcycle use. New approaches to the heterogeneous non-lane-based flow have been proposed. However insufficient empirical verification has been made to estimate vehicle interaction, that is necessary for an accurate representation of mixed-flow conditions. In this paper, we focus on the porous flow approach to capture the complex interactions. The parameters from this approach are estimated from empirical observations. Video data was recorded and processed to capture vehicle interactions at a number of road sections in Surabaya City, Indonesia. The specific behavior of each vehicle in the traffic flow was captured by developing the pore size–density distributions, analyzing the class-specific critical pore sizes, and producing the class specific speed–density and flow–density diagrams. The results reveal how critical pore sizes are based on pore size–density distributions, the flow diagram for each vehicle class, and how traffic flow relationships for motorcyclists and the other vehicles exhibit significant differences. It is concluded that the proposed approach can represent the specific behavior of the motorcyclist in heterogeneous traffic flow, in both the situations of with- and without an exclusive lane for motorcycles, can clarify motorcyclist’s behavior in terms of passenger car unit of motorcycle, and can therefore support policy making on the improvement of urban transport.

Approximation Algorithms for Mobile Data Caching in Small Cell Networks

Small cells constitute a promising solution for managing the mobile data growth that has overwhelmed network operators. Local caching of popular content items at the small cell base stations (SBSs) has been proposed to decrease the costly transmissions from the macrocell base stations without requiring high capacity backhaul links for connecting the SBSs with the core network. However, the caching policy design is a challenging problem especially if one considers realistic parameters such as the bandwidth capacity constraints of the SBSs that can be reached in congested urban areas. We consider such a scenario and formulate the joint routing and caching problem aiming to maximize the fraction of content requests served locally by the deployed SBSs. This is an NP-hard problem and, hence, we cannot obtain an optimal solution. Thus, we present a novel reduction to a variant of the facility location problem, which allows us to exploit the rich literature of it, to establish algorithms with approximation guarantees for our problem. Although the reduction does not ensure tight enough bounds in general, extensive numerical results reveal a near-optimal performance that is even up to 38% better compared to conventional caching schemes using realistic system settings.

Zoned Excavation of an Oversized Pit Close to an Existing Metro Line in Stiff Clay: Case Study

AbstractBecause greenfields available for new developments in congested urban areas are scarce in China, more and more excavations for building basements or other underground facilities (e.g., new metro lines, underground shopping malls, parking garages) have to be carried out in the close proximity of existing metro lines. To ensure project safety, it is essential to know potential adverse effects of excavations on adjacent metro lines in service. Until now, many studies have contributed to the cases of excavations overlying existing tunnels. In contrast, only a few were known for excavations parallel to adjacent existing tunnels. With regard to the responses of existing metro stations to adjacent excavations, few case studies were reported in the literature. Through an extensive field instrumentation program in combination of numerical simulations, this study examines the performance of an oversized deep excavation in stiff clayey deposits and the corresponding responses of the adjacent metro station an...

Evaluation of synergies from transportation policy packages using a social welfare maximization approach: A case study for Madrid, Spain

This paper discusses the evaluation of synergies that derive from the implementation of policy packages designed to promote the use of public transportation and limit traffic congestion in urban areas. In this study, we propose the application of a land-use and transportation integrated (LUTI) model to study the outcomes from the implementation of two policy packages. We apply the long-term strategic LUTI model MARS-Madrid to analyze an empirical case study in Madrid, Spain. The analyzed policies include a road pricing scheme (congestion charge) in the city center and an increase in the level of service of public transportation (bus frequency changes) in the whole region. Different scenarios, involving the implementation of respectively each one of these policies separately or both policies simultaneously, are simulated and compared to a base scenario (business as usual, or “do-nothing”). We evaluate the effects of these policies on several transportation indicators and on social welfare, and discuss the optimization of these policies in isolation or combined as a policy package. The study provides insights into the suitability of the proposed LUTI modeling approach to evaluate the impact of transportation policies in urban and metropolitan areas, and the evaluation of synergies from transportation policies, a topic that is not enough studied in the literature.

Assessing the Value of Delay to Short-Haul Carriers

This paper aims at examining the commercial vehicle operators’ value of delay (VOD) due to highway congestion inurban area. The VOD is a fundamental parameter that influences the private sector’s response to public freightprojects and policies. This paper adopts two methods to estimate the VOD; one being the stated preference (SP)survey and the other being simulation of a carrier’s fleet operations. The former applies a Logit model and estimates adriver perceived VOD as $56.48 per vehicle per hour for the regular short-haul delivers. The latter gauges theeconomic impact of delay on carrier’s fleet operations in the Houston highway network. The operations essentiallyreflect more of a just-in-time system due to the rather stringent time window constraints. The simulation is conductedon a rolling time horizon with a heuristic algorithm for dispatching trucks. The major findings include, but are notlimited to as follows. The drivers paid by miles perceive a significantly higher VOD than the others; the drivers aremore willing to pay for a faster trip when the toll charges do not come out of their own pockets; VOD increases withuncertainty and demand for capacity. The comparison between the survey and the simulation results also indicatesthat the interviewed drivers perceive a significantly lower VOD than they may actually experience as a fleet, anindicator of myopic vision.