Hierarchical Transport Network Research Articles

Mathematical Models of the Problem of Constructing Delivery Routes of Cargo in the Internal Zones of Trunk Nodes of a Hierarchical Transport Network

Mathematical Models of the Problem of Constructing Delivery Routes of Cargo in the Internal Zones of Trunk Nodes of a Hierarchical Transport Network

Spatial Regression in the Presence of a Hierarchical Transportation Network: Application to Land Price Analysis

Transportation networks have a hierarchical structure, and the spatial scale of their impact on urban growth differs depending on the hierarchy. However, in empirical analyses of the impacts that transportation has on land use and prices, such hierarchy is often examined using dummy variables, and the network dependence and heterogeneity of impacts are often ignored. Thus, this study develops a spatial regression method that considers not only spatial dependence, but also network dependence within a hierarchical transportation network. This method was developed by extending the random effects eigenvector spatial filtering approach. Subsequently, it was applied to a pre-existing analysis that focused on the impacts that high-speed rail (HSR) had on residential land prices in Japan over the last 30 years. The results of the analysis suggested that HSR lines had hierarchical effects on residential land prices. The results also provide interesting insight into the ongoing problem of Japanese urban hierarchy; that is, the excessive concentration of population and industry in the Tokyo metropolitan area.

A nonequilibrium thermodynamics perspective on nature-inspired chemical engineering processes

Nature-inspired chemical engineering (NICE) is promising many benefits in terms of energy consumption, resilience and efficiency etc. But it struggles to emerge as a leading discipline, chiefly because of the misconception that mimicking Nature is sufficient. It is not, since goals and constrained context are different. Hence, revealing context and understanding the mechanisms of nature-inspiration should be encouraged. In this contribution we revisit the classification of three published mechanisms underlying nature-inspired engineering, namely hierarchical transport network, force balancing and dynamic self-organization, by setting them in a broader framework supported by nonequilibrium thermodynamics, the constructal law and nonlinear control concepts. While the three mechanisms mapping is not complete, the NET and CL joint framework opens also new perspectives. This novel perspective goes over classical chemical engineering where equilibrium based assumptions or linear transport phenomena and control are the ruling mechanisms in process unit design and operation. At small-scale level, NICE processes should sometimes consider advanced thermodynamic concepts to account for fluctuations and boundary effects on local properties. At the process unit level, one should exploit out-of-equilibrium situations with thermodynamic coupling under various dynamical states, be it a stationary state or a self-organized state. Then, nonlinear phenomena, possibly provoked by operating larger driving force to achieve greater dissipative flows, might occur, controllable by using nonlinear control theory. At the plant level, the virtual factory approach relying on servitization and modular equipment proposes a framework for knowledge and information management that could lead to resilient and agile chemical plants, especially biorefineries.

Rationalizing Public Transport System of Dhaka City: Proposal of Creating a Multimodal Hierarchical Transport Network to Reduce Traffic Congestion

The concept of rationalization can be defined as a structured process to increase effectiveness through a maximize use of existing resources. Rationalization in terms of road infrastructure or systems can be achieved in various ways; establishing hierarchy of routes, optimize bus-stop points with density distribution changes, proper integration of motorized and non-motorized transport and providing policy framework. In the highly densely populated city of Dhaka, rationalizing public transport is one way to minimize the mismatch between demand and supply.
 This paper is concerned with the following issues: providing a general description of the city transport system, identifying problems and demands analysis in the area of study area; studying the rationalization of public transport, particularly public transport system design (routes and their categorization) and proposing the creation of a multimodal hierarchical transport network for Dhaka. The findings suggest establishing a major component, a hierarchal-network. Beside establishing network hierarchy, rationalizing is also interdependent upon system planning, institutional framework, organization and financing, terminal locations, public-private relationships, government roles, policies, service integration, and the management of public transport. This is can be accomplished by all stakeholders sharing the relative success and failure, depending different levels of each components’ performances. The findings of this paper will help planners and decision makers to optimize the investment in the transport infrastructure.

Mapping Time-Varying Accessibility and Territorial Cohesion With Time-Distorted Maps

Human societies have radically changed from the second half of the 20th century. Urban areas are increasingly concentrating more people and economic activities. Connections between market economies in different regions have increased exponentially the flow of people and goods at a global level. These movements are spatially organized through a hierarchical transportation network that connects different areas. The quality and coverage of such network vary greatly across regions. Territorial cohesion and accessibility within a region could be roughly evaluated through the existing level of connectivity between urban nodes. This can be easily done by estimating travel times between different points in the territory, which would show relevant differences based on both the territory itself and the existing infrastructure. Unfortunately, this information is not typically shown in traditional maps. In this paper, we propose a novel methodology for assessing the degree of territorial accessibility within and across urban networks, by using time-distorted maps. To this end, we consider multiple scenarios related to different public transport modes and times of the day. The study area corresponds to a Spanish region, where we set up a relatively extended network by considering its most relevant cities and towns. Final maps can clearly illustrate the deficiencies in transport infrastructure and/or connections from a spatial perspective. These maps can be excellent tools for supporting technicians, politicians, public managers, and other stakeholders in the decision-making process.

Interaction of maritime shipping and hinterland traffic using a two-level hierarchical transport network

A transport scenario based on a two-level network is developed in order to model operations in maritime transport. To enhance competitiveness and sustainability of shipping companies, the interaction between maritime shipping and hinterland traffic is considered in the novel two-level hierarchical transport network. Demand occurs on the second level, the hinterland, whereas the first level, the sea transport, acts as a pure distribution network. The two-level hierarchical transport model allows regulating the degree of interaction a liner operator has regarding the hinterland traffic. Moreover, access of vehicles to nodes or edges is given subject to feasibility constraints, relating to the size of a vehicle. In this work, the relation to existing routing models, such as the travelling salesman problem, the vehicle routing problem, or the travelling purchaser problem, is illustrated. Moreover, through the definition of a proper set of assumptions, it is possible to reduce the considered two-level hierarchical transport network to different standard routing models. These new insights allow the application of existing solution methods. Numerical experiments are conducted for a particular case and illustrate the influence of node costs on the distribution of workload to the vehicles.

Hierarchical Ethernet Transport Network Architecture for backhaul cellular networks

Cellular traffic has been going through major changes in recent years. With the introduction of broadband services in 3G/4G and the continuously increasing provided data rates in high-speed packet access and Long Term Evolution (LTE), a broad range of cellular applications has emerged, changing the characteristics of cellular traffic. The traditional circuit-switched voice traffic has been taken over by packet-oriented data traffic. This shift in traffic has driven operators to prefer packet-oriented network technologies over circuit-switch technology when implementing their cellular networks. The current offered technologies, including PBB-Traffic Engineering and MPLS-TP, lack important functionality required for LTE such as automation (simple management), traffic engineering, protection, Quality of Service, and scalability. We propose a scalable Hierarchical Ethernet Transport Network Architecture (HETNA), a layer 2 transport technology that addresses these issues and brings a viable solution for cellular networks. The suggested architecture can handle streaming, real-time, multicasting, and other applications. Both connection-oriented transport services and connectionless-oriented services are supported. HETNA was simulated and prototyped, showing significant improvements over regular Ethernet in terms of buffers and control messages that enable this network to function.

Deficiencies of existing public transport system and a proposal for integrated hierarchical transport network as an improvement options: a case of Dhaka city

Public transport plays an important role in providing easy and affordable accessibility and mobility for dwellers in a city. This demand for transportation is brought about by the increased population of connecting nodes, cities, the rural-urban migration, and the scope for socio-economical facilities i.e. better opportunities for jobs, health facilities and educational scope etc. thus the economic viability of the people which leads to an increase in the usage of private vehicles. Dhaka is an over densely populated city and its transport system comprised of many different modes of travel – both motorized and non-motorized using the same road space – resulting in a high level of operational disorder, that significantly diminishes the efficiency and effectiveness of the existing transport uses. Dhaka is experiencing lots of traffic congestion and a great lack of traffic management. There has been no study dedicated to overcome the situation. Therefore, there is an urgent need to introduce a well-organized, properly scheduled rapid mass transit system minimizing the existing deficiencies. In this paper, an attempt has been made to identify the deficiencies of existing public transport system to put forward for an appropriate rapid mass transit system to recover the huge demand. An overview of the existing modes of travel and operation characteristics has been described. Finally, some proposals for integrated hierarchical transport network options are highlighted with the context of prevailing land use and transport characteristics, socio-economic context of Dhaka Metropolitan city. The findings of this research help planners and decision makers to optimize the investment in transport infrastructure.

Accessibility of workers in a compact city:: the case of Hong Kong

This article investigates the relationship between the accessibility of workers and the compact city structure in Hong Kong. We are particularly concerned with the influences of land-use policy and public transport systems development on the accessibility of workers. We construct a model which incorporates factors such as transfers in work trips, employment status, income, gender, marital status and living in accessible areas to account for the accessibility of workers. Our findings show that whether a worker lives in an accessible area or not does not affect his or her accessibility, rather transfers in work trips have the greatest impact, indicating that variability in accessibility to jobs is different in a compact city structure with a hierarchical transport network from that in cities in Europe and the US. Although income is not a significant factor affecting the accessibility of workers, workers in Hong Kong have to bear high travel costs on transfers. Also noteworthy is the finding that married workers spend longer times on work trips than the workers who are single. It might be attributed to the fact that a high proportion of households employ foreign domestic helpers to take care of their housework so that they could spend more time on work trips.

Hierarchical VP restoration management system for a reliable ATM backbone network

AbstractThis paper proposes a distributed ATM VP PVC restoration framework with the dynamic rerouting schemes in a hierarchical transport network. The rerouting algorithm aims to provide rapid ATM VP PVC restoration in the case of fault or performance degradation in terms of maximization of network resource utilization and satisfaction of the end user's QoS requirement. Copyright © 2002 John Wiley & Sons, Ltd.

BFRA: bounded flooding routing algorithm for provisioning the globally optimal route in a hierarchical ATM network

ATM virtual path (VP) contains bundles of virtual channels (VCs). A VP layer network can be used as a server layer network of VC layer networks and each VC layer network can be a client layer. Therefore, the effective provision of VC services can be achieved by the more optimal routing scheme of the VP layer network. However, the traditional hierarchical routing scheme of PNNI signaling protocol does not provide the globally optimal route in hierarchical transport network due to its successive network partitioning and topology abstraction. We propose a new VP routing scheme suitable for the national wide hierarchical transport network and a network model suitable for the scalable VP network management system. The routing algorithm can provide the globally optimal route in the hierarchical network environment from the perspectives of maximization of network resource utilization and satisfaction of the end user's QoS requirement. In addition, we describe the implementation model of the ATM virtual path network management system (VP-NMS). Lastly, we show the routing performance evaluated in the high speed information network (HSIN) of Korea Telecom.

Optimal Design of a Two‐Level Transportation Network with a Different Unit Cost for Each Secondary Link*

ABSTRACTThe objective of this paper is to further develop Singhal's (1990) framework for designing a two‐level hierarchical transportation network consisting of a trunk or primary link and several feeder or secondary links. Secondary links are perpendicular lines from each of the given points and the primary link is a straight line or curve connecting the feet of two extreme perpendicular lines. The problem and the associated strategic and operational considerations such as cost, time, feasibility, and preferred regions for the primary link in the context of rural highway planning are discussed. Two‐level networks are also common in electricity transmission, pipelines, and telecommunication design.The core of the framework is a model for finding the path of a primary link such that a weighted sum of the lengths of the perpendicular lines from each point to a linear primary link and the distance between the feet of the two extreme perpendicular lines is minimized. The analysis shows that for almost every problem there exists a wide range of solutions for which the total cost is only slightly higher than that of the optimal solution. This offers considerable flexibility to the decision maker. These solutions can be evaluated in view of the broader objectives and constraints that are not included in the model. The use of computer graphics and the option of a nonlinear or piecewise linear primary link are also discussed.

Theory and methodology

The hierarchial network design problem with transshipment facilites was first formulated in Current, J. (1988), “The design of a hierarchical transportation network with transshipment facilities”, Transportation Science 22, 270–277. The objective of the FC-HNDP is to identify a least cost, two-level network. The network must include a primary path from a prespecified origin node to a prespecified terminus node. All nodes not on the primary path must be connected to that path via secondary arcs. In addition, transshipment facilities are required at the intersections of the two network levels. In this paper we present two efficient heuristics for solving the FC-HNDP. These heuristics were based upon a Lagrangian relaxation of the problem. To facilitate this relaxation, we have reformulated the original problem. Results for 240 randomly generated problems are summarized. The heuristics yielded the optimal solution in 72% of these problems. The mean gap between the Lagrangian lower bound and the feasible solution value was 0.38% and the maximum gap was 4.33% of the lower bound.

The Design of a Hierarchical Transportation Network with Transshipment Facilities

In this paper an integer linear program is formulated to identify the least cost two-level hierarchical network. This network must include a primary path from a predetermined starting node to a predetermined terminus node. In addition, each node not on the primary path must be connected to some node on that path via a secondary path. Transshipment facilities are required at the intersections of the primary and secondary paths. Consequently, the formulation directly considers the number and locations of transshipment facilities in determining the minimal cost network. A heuristic is presented which employs a K Shortest Path algorithm and a Minimum Spanning Tree algorithm. Heuristic results of two sample problems are presented and compared to the results obtained by solving the integer LP formulation.