scholarly journals Transport networks and their use: how real can modelling get?

2008 ◽  
Vol 366 (1872) ◽  
pp. 1879-1892 ◽  
Author(s):  
Richard E Allsop
Keyword(s):  
Steady State ◽  
Time Dependence ◽  
Transport System ◽  
Traffic Assignment ◽  
Analytical Modelling ◽  
Transport Systems ◽  
Transport Networks ◽  
Variable Demand ◽  
Assignment Model

The context for modelling transport systems and their use is set out. Such modelling is based on representing the transport system by a network of nodes and links, and the characteristics of this representation needed to reflect the principal realities of the system are outlined. The characteristics of use of the system that need to be reflected are described. Purposes of the modelling are set out and its evolution is described, starting from the basic traffic assignment model and discussing its generalizations and extensions in the search for greater realism—first in steady-state modelling for fixed demand, and then considering variable demand and time dependence. Further progress towards appropriate realism is seen as requiring communication and cooperation between the modellers and the users of models, helped perhaps by combining the advantages of analytical modelling and microsimulation.

scholarly journals CURRENT PROBLEMS AND PROSPECTS OF THE DEVELOPMENT OF THE CITY TRANSPORT SYSTEM

2018 ◽  
pp. 64-70 ◽  
Author(s):  
Volodymyr Postnikov
Keyword(s):  
Transport System ◽  
Heavy Traffic ◽  
Urban Transport ◽  
Economic Situation ◽  
European Countries ◽  
Transport Systems ◽  
Transport Networks ◽  
Rational Use ◽  
Foreign Experience ◽  
The City

Modern conditions of the development dictate new conditions for the improvement and operation of urban transport. It is primarily due to the heavy traffic of urban transport networks and a change in the approaches to their exploitation. However, the objective economic situation does not provide opportunities for the full use of its potential. Thus, the full and rational use of existing opportunities becomes possible only in case of determining the priority directions of its development, and, accordingly, their implementation, which in turn updates the research and forms its purpose. In this way, the involvement of foreign experience in the operation of the urban transport system, taking into account national realities, is of great importance. The main approaches to the elements of the urban transport are defined. The key components of this system are outlined. The main models of regulation and financial provision of the urban transport system have been investigated. The experience of European countries in this area has been systematized. The main directions of the development of the urban transport systems in Ukraine have been proposed.

Level-Based Approach to Public Transport Network Planning

2015 ◽  
Vol 2537 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Hermann Orth ◽  
Andrew Nash ◽  
Ulrich Weidmann
Keyword(s):  
Transport System ◽  
Public Transport ◽  
Transport Network ◽  
Transport Systems ◽  
Operating Characteristics ◽  
Transport Networks ◽  
Long Distance ◽  
Large Cities ◽  
The Public ◽  
Public Transport System

The public transport network level is defined and is used to describe the performance and future improvement of the public transport system in Zurich, Switzerland. A public transport level is a specific type of service designed to serve a particular market. “Service” is defined as a combination of vehicles, infrastructure, and operating characteristics. A pure level occurs when the service is targeted specifically at one particular market. A hybrid level occurs when a service is targeted to serve several markets. Urban travel is generally described as three markets: short, inter mediate, and long-distance trips. Consequently many cities have developed three-level public transport networks: surface buses and trams to serve short trips, rapid rail to serve intermediate trips, and regional rail to serve longer-distance trips. Often, by design or for historic reasons, cities have additional levels, fewer levels, levels that are not precisely matched to their markets, or all three. For example, two-level networks are often found in medium-sized cities. Their advantage is lower costs, and their main disadvantage is a mismatch between transport mode and market that manifests itself in capacity limitations. The level concept to help analyze and plan public transport service is useful because it focuses attention on matching service qualities to markets. This approach, used here to analyze the success of the public transport system of Zurich, Switzerland, and to provide a structure for planning improvements that will be needed to meet rapidly increasing public transport demand, could help other cities design or redesign their public transport systems to be more attractive and efficient. More specifically, the approach could show how two-level public transport networks would be a viable option for medium-sized cities and large cities with dispersed settlement patterns.

scholarly journals A Practical Traffic Assignment Model for Multimodal Transport System Considering Low-Mobility Groups

Mathematics ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 351 ◽  
Author(s):  
Tao Zhang ◽  
Yang Yang ◽  
Gang Cheng ◽  
Minjie Jin
Keyword(s):  
Transport System ◽  
Traffic Assignment ◽  
Transportation Network ◽  
Travel Costs ◽  
Assignment Model ◽  
Proposed Model ◽  
Multimodal Transport ◽  
Logit Function ◽  
Private Car

In this study, we created a practical traffic assignment model for a multimodal transport system considering low-mobility groups with the aim of providing the foundation of transportation network design for low-mobility individuals. First, the route choice equilibrium for walking, non-vehicle, and private car modes is described using the logit function, which is formulated as a variational inequality problem considering different low-mobility groups. Then, the practicalities related to travel times at intersections, traffic barricades between different lanes, and fuel fees of private cars are integrated to design a generalized travel cost function. Last, the method of successive weight averages is used to solve the proposed model. The model and its solution are verified based on a real case study of the city of Wenling in China. The sensitivity of adjustment parameters related to travel costs are analyzed, the practicality of the proposed model is explored, and the results of traffic assignment for different low-mobility groups are discussed.

The Role of Politics in the Historical Transport Networks of the Iberian Peninsula and the Pyrenees from Roman Times to the Nineteenth Century

2021 ◽  
Vol 45 (2) ◽  
pp. 233-260
Author(s):  
Pau de Soto ◽  
Cèsar Carreras
Keyword(s):  
Iberian Peninsula ◽  
Social Factors ◽  
Transport Network ◽  
Political Organization ◽  
Transport Systems ◽  
The Political ◽  
Political Systems ◽  
Transport Networks ◽  
Political Economic

AbstractTransport routes are basic elements that are inextricably linked to diverse political, economic, and social factors. Transport networks may be the cause or result of complex historical conjunctions that reflect to some extent a structural conception of the political systems that govern each territory. It is for this reason that analyzing the evolution of the transport routes layout in a wide territory allows us to recognize the role of the political organization and its economic influence in territorial design. In this article, the evolution of the transport network in the Iberian Peninsula has been studied in a broad chronological framework to observe how the different political systems of each period understood and modified the transport systems. Subsequently, a second analysis of the evolution of transport networks in the northeast of the Iberian Peninsula is included in this article. This more detailed and geographically restricted study allows us to visualize in a different way the evolution and impact of changes in transport networks. This article focuses on the calculation of the connectivity to analyze the intermodal transport systems. The use of network science analyses to study historical roads has resulted in a great tool to visualize and understand the connectivity of the territories of each studied period and compare the evolution, changes, and continuities of the transport network.

Heave Induced Internal Flow Fluctuations in Vertical Transport Systems for Deep Ocean Mining

2014 ◽  
Author(s):  
Stephan D. A. Hannot ◽  
Jort M. van Wijk
Keyword(s):  
Transport System ◽  
Internal Flow ◽  
Deep Ocean ◽  
Vertical Transport ◽  
Transport Systems ◽  
Ship Motions ◽  
Centrifugal Pumps ◽  
Mining System ◽  
Pump System ◽  
Ocean Mining

Deep ocean mining systems will have to operate often in harsh weather conditions with heavy sea states. A typical mining system consists of a Mining Support Vessel (MSV) with a Vertical Transport System (VTS) attached to it. The transport system is a pump pipeline system using centrifugal pumps. The heave motions of the ship are transferred to the pump system due to the riser-ship coupling. Ship motions thus will have a significant influence on the internal flow in the VTS. In this paper, the influence of heave motions on the internal flow in the VTS for a typical mining system for Seafloor Massive Sulfide (SMS) deposits in Papua New Guinea is analyzed. Data on the wave climate in the PNG region is used to compute the ship motions of a coupled MSV-VTS. The ship motions then are translated into forces acting on the internal flow in order to compute fluctuations in the internal flow. In this way, the workability of the mining system with respect to the system’s production can be assessed. Based on a detailed analysis of the internal flow in relation to ship motions, the relevance of a coupled analysis for the design of VTS is made clear. This paper provides a method for performing such analyses.

scholarly journals Trk2 Potassium Transport System in Streptococcus mutans and Its Role in Potassium Homeostasis, Biofilm Formation, and Stress Tolerance

2016 ◽  
Vol 198 (7) ◽  
pp. 1087-1100 ◽  
Author(s):  
Gursonika Binepal ◽  
Kamal Gill ◽  
Paula Crowley ◽  
Martha Cordova ◽  
L. Jeannine Brady ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Streptococcus Mutans ◽  
Transport System ◽  
Biofilm Formation ◽  
Cellular Response ◽  
Pathogenic Bacteria ◽  
Transport Systems ◽  
Content Type ◽  
Growth And Survival ◽  
Dental Biofilm

ABSTRACTPotassium (K+) is the most abundant cation in the fluids of dental biofilm. The biochemical and biophysical functions of K+and a variety of K+transport systems have been studied for most pathogenic bacteria but not for oral pathogens. In this study, we establish the modes of K+acquisition inStreptococcus mutansand the importance of K+homeostasis for its virulence attributes. TheS. mutansgenome harbors four putative K+transport systems that included two Trk-like transporters (designated Trk1 and Trk2), one glutamate/K+cotransporter (GlnQHMP), and a channel-like K+transport system (Kch). Mutants lacking Trk2 had significantly impaired growth, acidogenicity, aciduricity, and biofilm formation. [K+] less than 5 mM eliminated biofilm formation inS. mutans. The functionality of the Trk2 system was confirmed by complementing anEscherichia coliTK2420 mutant strain, which resulted in significant K+accumulation, improved growth, and survival under stress. Taken together, these results suggest that Trk2 is the main facet of the K+-dependent cellular response ofS. mutansto environment stresses.IMPORTANCEBiofilm formation and stress tolerance are important virulence properties of caries-causingStreptococcus mutans. To limit these properties of this bacterium, it is imperative to understand its survival mechanisms. Potassium is the most abundant cation in dental plaque, the natural environment ofS. mutans. K+is known to function in stress tolerance, and bacteria have specialized mechanisms for its uptake. However, there are no reports to identify or characterize specific K+transporters inS. mutans. We identified the most important system for K+homeostasis and its role in the biofilm formation, stress tolerance, and growth. We also show the requirement of environmental K+for the activity of biofilm-forming enzymes, which explains why such high levels of K+would favor biofilm formation.

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