Evolution Of Transport Networks Research Articles

Graph-based ahead monitoring of vulnerabilities in large dynamic transportation networks.

Betweenness Centrality (BC) has proven to be a fundamental metric in many domains to identify the components (nodes) of a system modelled as a graph that are mostly traversed by information flows thus being critical to the proper functioning of the system itself. In the transportation domain, the metric has been mainly adopted to discover topological bottlenecks of the physical infrastructure composed of roads or railways. The adoption of this metric to study the evolution of transportation networks that take into account also the dynamic conditions of traffic is in its infancy mainly due to the high computation time needed to compute BC in large dynamic graphs. This paper explores the adoption of dynamic BC, i.e., BC computed on dynamic large-scale graphs, modeling road networks and the related vehicular traffic, and proposes the adoption of a fast algorithm for ahead monitoring of transportation networks by computing approximated BC values under time constraints. The experimental analysis proves that, with a bounded and tolerable approximation, the algorithm computes BC on very large dynamically weighted graphs in a significantly shorter time if compared with exact computation. Moreover, since the proposed algorithm can be tuned for an ideal trade-off between performance and accuracy, our solution paves the way to quasi real-time monitoring of highly dynamic networks providing anticipated information about possible congested or vulnerable areas. Such knowledge can be exploited by travel assistance services or intelligent traffic control systems to perform informed re-routing and therefore enhance network resilience in smart cities.

The evolution of transport networks and the regional water environment: the case of Chinese high-speed rail

ABSTRACT We investigate empirically the role of an evolving high-speed rail (HSR) network in improving the regional water environment via industry agglomeration. We use Graph Theory to construct a data set reflecting a continuous evolution of cities’ accessibility to the HSR network. We find that cities with higher degree and closeness centralities in the HSR network tend to have less industrial water pollution. The reallocation of a high-skilled labour force leads to the agglomeration of skill-intensive and clean industries in cities with higher HSR centralities. We show that the evolution of the HSR networks is indeed conducive to the sustainable regional development.

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

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.

Identifying cultural heritage corridors for preservation through multidimensional network connectivity analysis — a case study of the ancient Tea-Horse Road in Simao, China

ABSTRACT Due to the development and evolution of transportation networks, and the destruction and disappearance of cultural heritage in the urbanisation process, it is imperative to protect historical and cultural heritage using various public policy tools. Identifying heritage sites is a critical first step in achieving subsequent successful preservation. However, few extant studies have explored methods to identify heritage corridors using network analysis approaches. This study uses multidimensional network connectivity analysis to identify cultural heritage corridors along the ancient Tea-Horse Road. Based on the theory of occurrence, this paper considers the hierarchical factors such as time, space, ethnic culture, religious culture, and altitude differences in landscape patches to explore how these corridors are connected through a multidimensional network. The study fills a void in current literature and presents a spatially integrated multidimensional approach identifying cultural heritage corridors, making it possible for the protection, preservation, and development of these corridors.

Spatiotemporal evolution of land transportation networks and accessibility in inland mountainous areas 1917–2017: A case study of Southwest China

Located in the western hinterland, Southwest China is a typical mountainous area covered by plateaus, mountains and hills. Its ruggedness hinders regional internal and external connections, and its poor transportation infrastructure has long constrained the socioeconomic development of Southwest China. Based on the GIS transportation database, this paper explored the spatiotemporal evolution and characteristics of the land transportation networks and the accessibility of Southwest China from 1917 to 2017. Regional accessibility in Southwest China has significantly improved, and transportation infrastructure has gradually integrated the transportation circles of the 52 central cities. The transportation network has followed an evolutionary process from a “hub-spoke pattern” to a “network pattern”, while the construction of a high-speed railway (HSR) has brought about significant spatial polarization. We argue that innovation in transportation technology is one of the most effective factors for promoting a significant change in regional accessibility. In addition, the spatial distribution and evolution of accessibility in Southwest China presents a vertical characteristic that distinguishes it from the plains, as the spillover effects of new transportation infrastructure on accessibility improvement are partly offset by the mountainous terrain. Additionally, in Southwest China, there is significant “path dependence” in the evolution of the transportation network, since a large portion of the population is concentrated along transportation corridors in mountainous areas.

Revisiting the coupling between accessibility and population growth

The coupling between population growth and transport accessibility has been an elusive problem for more than 60 years now. Due to the lack of theoretical foundations, most of the studies that considered how the evolution of transportation networks impacts the population growth are based on regression analysis in order to identify relevant variables. The recent availability of large amounts of data allows us to envision the construction of new approaches for understanding this coupling between transport and population growth. Here, we use a detailed dataset for about 36 000 municipalities in France from 1968 until now. In the case of large urban areas such as Paris, we show that growth rate statistical variations decay in time and display a trend towards homogenization where local aspects are less relevant. We also show that growth rate differences due to accessibility are very small and can mostly be observed for cities that experienced very large accessibility variations. This suggests that the relevant variable for explaining growth rate variations is not the accessibility but its temporal variation. We propose a model that integrates the stochastic internal variation of the municipalities population and an inter-urban migration term that we show to be proportional to the accessibility variation and has a limited time duration. This model provides a simple theoretical framework that allows to go beyond econometric studies and sheds a new light on the impact of transportation modes on city growth.

The dynamics of transportation networks

ABSTRACTAlan Wilson’s contributions to the development of dynamic models of network evolution are presented in this manuscript. His ideas, first represented in the dynamic retail model, were transferred to the task of modelling the evolution of transport networks. He also anticipated the question of handling multi-modal situations. Indeed, his model could be formulated in a way that the focus could be on the effect of given variables – for example public transport fares or parking provision and charging – and hence of exploring ways of using these models in a policy context.

A scale-free transportation network explains the city-size distribution

Zipf's law is one of the best known empirical regularities in urban economics. There is extensive research on the subject, where each city is treated symmetrically in terms of the cost of transactions with other cities. Recent developments in network theory facilitate the examination of an asymmetric transport network. In a scale‐free network, the chance of observing extremes in network connections becomes higher than the Gaussian distribution predicts and, therefore, it explains the emergence of large clusters. The city‐size distribution shares the same pattern. This paper decodes how accessibility of a city to other cities on the transportation network can boost its local economy and explains the city‐size distribution as a result of its underlying transportation network structure. We confirm our model predictions with US and Belgian data. Finally, we discuss the endogenous evolution of transport networks. Zipf's law city‐size distribution scale‐free network L14 R12 R40

Physarum computing and topology optimisation

The plasmodium stage of the giant single-celled amoeboid organism Physarum polycephalum, or true slime mould, dynamically adapts its body plan in response to environmental stimuli, including nutrient location, temperature gradients, light exposure, and predatory threats. The construction and adaptation of the plasmodial transport network has been shown to be an efficient trade-off between minimising network distance and maximising connectivity. Optimisation of topology is also a desired trait in manufacturing and engineering, whereby the topology of an initially simple component is modified to minimise one or more properties (for example minimising the amount of substrate reduces the weight and material cost of the component) whilst maintaining other desired material properties within the component (for example strength under specific load points and conditions). Biologically inspired approaches to certain specific engineering challenges are well documented and successful. In this paper we explore at a more general level whether a cross-pollination can occur between Physarum computing and Topology Optimisation. Using an interdisciplinary modelling approach we explore whether the evolution of transport networks in a multi-agent model of Physarum has any similarities to networks formed by Topology Optimisation. We find that the Topology Optimisation method generates networks which are similar to the model slime mould networks. The Topology Optimisation networks correspond to higher regions of the Toussaint hierarchy of proximity graphs (i.e. more edges) whereas the model slime mould networks exhibit greater minimisation of network length. Since it is possible to adjust network connectivity in the multi-agent model via nutrient concentration we speculate that similar parametric adjustment may be possible to alter the connectivity of Topology Optimisation networks.

Space P-Based Empirical Research on Public Transport Complex Networks in 330 Cities of China

The current empirical studies on public transport network of the cities in China are still limited to several large cities such as Beijing, Shanghai and Guangzhou. And the researches on whether the common topologies of public transport network for cities in different scales do not rely on some extend factors such as population, society or economic, and the researches on the evolutionary mechanisms of public transport network are still limited. This paper studies the public transport networks of 330 cities in China based on the space P concept. Statistical results show that the degree distribution of all networks can be described by an exponential function. It reveals that the evolution mechanism of public transport network is randomly connected instead of preferential attached. All the networks show typical small-world behaviors which characterized by larger clustering coefficient and smaller average shortest path. A transition between the dissortative small networks N<1,000 and assortative large networks N7gt;1,000 is observed. Average clustering coefficient of nodes with degree k decreases with k as a power law, shows that city bus transfer networks are well characterized by hierarchical modularity. The results of this study may provide guidance and reference for researches on evolution mechanism of urban public transport systems and transport network evolution modeling.

Optical transport network evolution: hot standardization topics in ITU-T including standards coordination aspects

The dramatic increase in capacity of telecommunication networks since the mid-1970s has been enabled by the introduction of light-wave systems for transmission. Since that time, services have evolved from voice and fax at 64 kbit/s to Ethernet and other data services at many Gbit/s, while the transmission technologies have evolved from GaAs 850 nm semiconductor lasers over multimode fiber to single mode fiber systems operating at 1300 nm, and later to multiwavelength systems operating at 1550 nm. This paper describes the evolution in services, frame formats, and optical technology along with the supporting ITU-T standardization activities that have fueled this development.

A MULTISCALE CELLULAR AUTOMATA MODEL FOR SIMULATING COMPLEX TRANSPORTATION SYSTEMS

We present a new two-level numerical model describing the evolution of transportation network. Two separate but mutually interacting sub-systems are investigated: a starving environment and the network. We assume that the slow modes of the environment growth can be modeled with classical cellular automata (CA) approach. The fast modes representing the transportation network, we approximate by the graph of cellular automata (GCA). This allows the simulation of transportation systems over larger spatio-temporal scales and scrutinizing global interactions between the network and the environment. We show that the model can mimic the realistic evolution of complex river systems. We also demonstrate how the model can simulate a reverse situation. We conclude that the paradigm of this model can be extended further to a general framework, approximating many realistic multiscale transportation systems in diverse fields such as geology, biology and medicine.

Layer 1 virtual private networks: driving forces and realization by GMPLS

This article describes an emerging service for next-generation networks, layer 1 virtual private networks. L1VPNs allow customers desiring to connect multiple sites to be supported over a single shared layer 1 network. In the article we first describe the transport network's evolution and the shift in expectations of both service providers and customers. We provide an overview of the motivation for L1VPNs and examples of network usage. We follow by reviewing existing GMPLS mechanisms (addressing, discovery, and signaling) for realizing L1VPN functionality and identifying other work areas.

Central place theory and evolution phenomenon

The evolution of the urban systems goes through different stages. The first is the formation of the whole system where the conformity to the rank-size rule is improving. The second is the transition from the quasi-amorphous state to the quasi-crystalline state where the conformity to the rank-size rule is getting worse, but the conformity to the central place theory is improving. The relativistic central place theory makes the spacing of the central places and their size interdependent. The attractor of the evolution of the central places systems is the state of isostatic equilibrium – the complete compensation of the deviation from the theory predictions by the spacing of the central places. The size of the central places is determined in another way than in the classical theory. The type of Christaller’s hierarchy – the K – is depending on the degree of the urbanisation and changes during the evolution of the central systems. So that the virtual hierarchies K=5 and K=6 which are not conforming to any optimization principle do exist. When the urban population is below 50% K=3, if it is between 50% and 60% - K=4, for 70 – 80% K=5, if it is about 90% - K=6 and the extreme quantity of the urban population – 100% corresponds to K=7. The evolution of the central places systems is closely related to the transition of urban systems from one Gibbs stage of urbanisation to another and with the evolution of transport networks. Many national and regional urban systems were studied in order to test these statements and the results were satisfactory.

Photonic transport networks based on optical paths

AbstractThis paper explores the technologies that will enable a further leap forward in transport network evolution. First, requirements of the future transport network are elucidated. Existing network cost is evaluated and the viable means to reduce transport network cost are identified. It is demonstrated that optical path technologies such as WP (wavelength path) and VWP (virtual wavelength path) will play a key role in this. They enhance not only transmission capacity but also cross‐connect node throughput cost‐effectively by capitalizing on the wavelength routeing scheme. Optical path realization technologies focusing on optical path cross‐connect systems are examined. Requirements for the optical path cross‐connect system are then elucidated, and a new cross‐connect system architecture is evaluated. The architecture exploits PLC (planar lightwave circuit) and other commercially available technologies suitable for large‐scale production. The evaluations include cross‐connect node upgradability, modular growth capability, total node cost, optical loss and switching power consumption. It is proved that the architecture has significant advantages over existing switch architectures. The optical path technologies provided in this paper will pave the way for a new transport network paradigm, a ubiquitous, bandwidth‐abundant and affordable broadband ISDN.