737,531 research outputs found
Container Transportation Network Equilibrium Analysis Considering Draft of Vessel
This paper analyzes container transportation network equilibrium considering draft of vessels. Concept of load factor (λ) of ship is included in the model. Three players are considered, i.e. port administrator, ship companies (carriers), and shippers. Interaction of these players leads to Nash equilibrium problem. The result of the model calculation indicates that Hong Kong and Singapore port dominates container throughput in the world and the big vessel (3000 - 6000 TEU) is dominant in these ports. Conversely, the smaller port with depth less than 15 m dominated by 1000 TEU vessels. The result is inline with the reality. The other finding from the study is 6000 TEU vessels can enter port with depth less than 15 m such as port of Shanghai. Again, it is inline with reality. Validation of the model shows that coefficient of determination (R2) is 0.95. It indicates the model provides good accuracy
A Model of the Rise and Fall of Roads
Transportation network planning decisions made at one point of time can have profound impacts in the future. However, transportation networks are usually assumed tobe static in models of land use. A better understanding of the natural growth pattern of roads will provide valuable guidance to planners who try to shape the future network. This paper analyzes the relationships between network supply and travel demand, and describes a road development and degeneration mechanism microscopically at the linklevel. A simulation model of transportation network dynamics is developed, involving iterative evolution of travel demand patterns, network revenue policies, cost estimation,and investment rules. The model is applied to a real-world congesting network â the Twin Cities transportation network which comprises nearly 8,000 nodes and more than 20,000 links, using network data collected since year 1978. Four experiments are carried out with different initial conditions and constraints, the results from which allow us toexplore model properties such as computational feasibility, qualitative implications, potential calibration procedures, and predictive value. The hypothesis that roadhierarchies are emergent properties of transportation networks is confirmed, and the underlying reasons discovered. Spatial distribution of capacity, traffic flow, andcongestion in the transportation network is tracked over time. Potential improvements to the model in particular and future research directions in transportation network dynamicsin general are also discussed.Transportation network dynamics, Urban planning, Road suppl
Paving New Ground
This paper explores the inter-connectedness and co-evolution of transportation networks and land use through the application of a Markov Chain model to the Twin Cities from 1958 through 1990. This model investigates how individual cells, with both land use and transportation network attributes, change over time. Cells with more transportation network available are more likely to develop, and cells that are developed are more likely to attract additional highway investment.Transportation Network Growth, Transportation-Land Use Interaction, Markov Chain
The worldwide air transportation network: Anomalous centrality, community structure, and cities' global roles
We analyze the global structure of the world-wide air transportation network,
a critical infrastructure with an enormous impact on local, national, and
international economies. We find that the world-wide air transportation network
is a scale-free small-world network. In contrast to the prediction of
scale-free network models, however, we find that the most connected cities are
not necessarily the most central, resulting in anomalous values of the
centrality. We demonstrate that these anomalies arise because of the
multi-community structure of the network. We identify the communities in the
air transportation network and show that the community structure cannot be
explained solely based on geographical constraints, and that geo-political
considerations have to be taken into account. We identify each city's global
role based on its pattern of inter- and intra-community connections, which
enables us to obtain scale-specific representations of the network.Comment: Revised versio
Chapter 13Â -Â Sharing strategies: carsharing, shared micromobility (bikesharing and scooter sharing), transportation network companies, microtransit, and other innovative mobility modes
Shared mobilityâthe shared use of a vehicle, bicycle, or other modeâis an innovative transportation strategy that enables users to gain short-term access to transportation modes on an âas-neededâ basis. It includes various forms of carsharing, bikesharing, scooter sharing, ridesharing (carpooling and vanpooling), transportation network companies (TNCs), and microtransit. Included in this ecosystem are smartphone âappsâ that aggregate and optimize these mobility options, as well as âcourier network servicesâ that provide last mile package and food delivery. This chapter describes different models that have emerged in shared mobility and reviews research that has quantified the environmental, social, and transportation-related impacts of these services
The Weakest Link: A Model of the Decline of Surface Transportation Networks
This study explores the economic mechanisms behind the decline of a surface transportation network, based on the assumption that the decline phase is a spontaneous process driven by decentralized decisions of individual travelers and privatized links. A simulation model is developed with a degeneration process by which the weakest link is removed iteratively from the network. Experiments reveal how the economic efficiency of a network evolves during the degeneration process and suggest an 'optimal' degenerated network could be derived during the decline phase in terms of maximizing total social welfare. Keywords: decline, transportation network, degeneration, welfare, accessibilityNetworks, Transportation, Structure, Entropy, Pattern, Continuity
Robustness and Closeness Centrality for Self-Organized and Planned Cities
Street networks are important infrastructural transportation systems that
cover a great part of the planet. It is now widely accepted that transportation
properties of street networks are better understood in the interplay between
the street network itself and the so called \textit{information} or
\textit{dual network}, which embeds the topology of the street network
navigation system. In this work, we present a novel robustness analysis, based
on the interaction between the primal and the dual transportation layer for two
large metropolis, London and Chicago, thus considering the structural
differences to intentional attacks for \textit{self-organized} and planned
cities. We elaborate the results through an accurate closeness centrality
analysis in the Euclidean space and in the relationship between primal and dual
space. Interestingly enough, we find that even if the considered planar graphs
display very distinct properties, the information space induce them to converge
toward systems which are similar in terms of transportation properties
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