Reliability Of Transportation System Research Articles

Optimal Routing Problem in Dynamic Stochastic Networks

Accidents, bad weather, traffic congestion, etc. contribute to the uncertainties of travel times in real-life transportation networks, which greatly affect the quality of individual life and the reliability of transportation system. In this paper, optimal routing problem is addressed in dynamic transportation networks with random link travel times. Taking the reliability of travel time into consideration, the robust schedule delay is used as the criterion of optimality to evaluate the paths, which is defined as minimizing the largest difference between the actual arriving time and the desired arrival time in dynamic stochastic networks. Under the stochastic consistent condition, a mathematic proof is given to simplify the problem. Then an exact modified Dijkstra's algorithm is designed for finding the optimal routing in STD networks and its computation complexity is calculated as a polynomial-time o(n2 *e). The validity of the proposed algorithm is also confirmed by conducting a test in a sampled network.

Estimation of its sensor operational states by analyzing measurements with errors using a Hidden Markov Model

One of the prominent problems in introducing autonomous and advanced transportation technologies to existing traffic network systems is the lack of a framework that constantly evaluates measurement reliability and consistency of Intelligent Transportation System (ITS) sensors. In order to tackle this problem, one needs to identify the sensor state rather than the measurement itself because statistical properties of the measurement noise profile in the ITS sensor vary from situation to situation, whereas the number of states a sensor can attain remain the same. Therefore, this paper develops a stochastic model that uses a Hidden Markov Model (HMM) to identify ITS sensor states from observed measurements with two supplemental modules (i.e., a Rule-based Diagnosis Module and a Statistic and Neighbor Feedback Module). Also, this paper tests the proposed model using an aggregated dataset (15 minute interval) obtained from a portion of Interstate 40 (I-40) in Knoxville, Tennessee, which was simulated to increase the resolution by an off-the-shelf microscopic simulation model (i.e., VISSIM). The case study results indicate that the HMM coupled with two supplemental modules can accurately identify sensor operational states more than 98% of the time and its performance is consistent along all the Inductive Loop Detector (ILD) stations.

A New Computing Mathematical Model about Surge Links Capacity in Logistics Transportation System and its Solving Algorithm Fitted for Computer Programming

The surge bin is widely used in logistics transportation system. Theoretically it has many virtues, such as reducing the interacting of links ahead and behind bin, buffering different transporting flows, adjusting and processing materials. In practical application, bin capacity size has great influence on reliability and production efficiency of whole logistics transportation system. Studying optimum computing of surge bin capacity to fully realize its beneficial functions are very significance. By utilizing some existing outcomes, this paper presents a new computing mathematical model about surge bin capacity in logistics transportation system. Compared with some existed references, this presented model fully considers different influences of surge bin capacity on reliability and production efficiency of whole logistics transportation system and realizes reliability and production efficiency overall optimization decision. All kind of factors affecting designed surge bin capacity can be easily gotten by the presented model. In addition this paper also presents a set of detailed design computing formulas about surge bin capacity in logistics transportation system, and presents detailed solving algorithm and steps fitted for computer programming. These can offer the reference for capacity decision design computing of surge bin in logistics transportation system.

Emergency Management of Urban Rail Transportation Based on Parallel Systems

Integrating artificial systems, computational experiments, and parallel execution (ACP) is an effective approach to modeling, simulating, and intervening real complex systems. Emergency response is an important issue in the operation of urban rail transport systems for ensuring the safety of people and property. Inspired by the ACP method, this paper introduces a basic framework of parallel control and management (PCM) for emergency response of urban rail transportation systems. The proposed framework is elaborated from three interdependent aspects: Points, Lines, and Networks. Points represent the modeling of urban rail stations, Lines describe the microscopic characteristics of urban rail connections between designated stations, and Networks present the macroscopic properties of all the urban rail connections. Based on the given framework, a series of parallel experiments, which were impossible to achieve in real systems, can now be conducted in the constructed artificial system. Furthermore, the constructed artificial system can be used to test and develop effective emergency control and management strategies for real rail transport systems. Therefore, this proposed framework will be able to enhance the reliability, security, robustness, and maneuverability of urban rail transport systems in case of an emergency.

Impact of Infrastructure Type on Reliability of Railway Transportation System / Wpływ Rodzaju Infrastruktury Na Niezawodność Systemu Transportu Szynowego

Abstract In this paper, the author’s research work is focused on infrastructure impact on railway transportation system reliability. The aim of research described in the paper is to determine correlation between type (and age) of used infrastructure elements, and number of occurring failures. For this purpose, subsystem of infrastructure and associated with it events, were divided into main groups. Examples of groups are: track, train operation devices (related to operating control points or railway line), level crossings, etc. The second aspect is correlation between type of infrastructure and failure consequences. It is required from transportation that it is possible to achieve the right place at the right time in a safety way. Therefore, from the point of view of transportation process, which is the main goal of transportation system, the most significant failure consequences are delays. Moreover, speaking about reliability and safety of railway transportation system, the question arises what is the relation between number of trains and number of unwanted events?

What do commuters think travel time reliability is worth? Calculating economic value of reducing the frequency and extent of unexpected delays

The measurement of transportation system reliability has become one of the central topics of travel demand studies. A growing literature concerns the measurement of value of travel time reliability which provides a monetary cost of avoiding unpredictable travel time. The goal of this study is to measure commuters’ sensitivities to travel time reliability and their willingness to pay (WTP) to avoid unreliable routes. The preferences are elicited through a pivoted stated preference survey technique. To circumvent the issue of presenting numerical distributions and statistical terms to day-to-day commuters, we use the frequency of delay days as a means of measuring traveler’s sensitivities to travel time reliability. The advantage of using simplified measures to elicit traveler preferences for travel time reliability is that these methods simply compare days with high delay to days with usual travel time. It was found that travelers are not only averse to the amount of unexpected delay but also to the frequency of days with unexpected delays. The paper presents WTP findings for three measures: travel time, frequency embedded travel time, and travel time reliability. The ‘reliability’ increase in WTP for travel time is found to be nearly proportional to the frequency of experiencing unexpected delays. For example, the WTP for mean travel time is calculated at $6.98/h; however, reliability adds $3.27 (about 50 % of $6.98) to avoid unexpected delays ‘5 out of 10 days’. The results of the study would provide valuable inputs to cost-benefit analyses and traffic and revenue studies required for road tolling investment projects.

Methodologies for supervision of Hybrid Energy Sources based on Storage Systems – A survey

Hybrid Energy Sources based on Storage Systems (HES) are increasingly used to improve the grid integration of renewable energy generators, or to improve the energy efficiency and the reliability of transport systems. This paper proposes a survey on the methodologies to design fuzzy logic based supervision strategies of this new kind of energy generating systems. Different ways to manage energy storage system are particularly discussed.A graphical modeling tool is used to facilitate the analysis and the determination of fuzzy control algorithms adapted to complex hybrid systems. The methodology is divided in different steps covering the design of a supervisor from the system work specifications to an optimized implementation of the control.An Experimental Design Methodology (EDM) combined with optimization algorithms is used to tune a set of parameters suitable for a fuzzy supervisor in order to optimize power, energy, efficiency, voltage quality, economic or environmental indicators.The application of this methodology to the supervision of different topologies of HES, based on renewable energy in a grid or in building applications or dedicated to transport systems, illustrates the performance and the systematic dimension of the approach.

Urban Public Transport System's Reliability Estimation Using Microscopic Simulation

Urban Public Transport System's Reliability Estimation Using Microscopic Simulation In the article the procedure of the reliability measures estimation for one route of the public transport network on the basis of a traffic flow modelling is suggested. A definition of UPTS reliability is based on the analysis of the Travel Time Reliability, Arrival Time Reliability and Probability of arriving to the stops with delay no more than m minutes. The approach is applied to the real task of the reliability estimation for Riga city public transport route. The microscopic model of transport network fragment is used for it.

MS Location Estimation with Genetic Algorithm

Intelligent transportation system (ITS) makes use of vehicle position to decrease the heavy traffic and improve service reliability of public transportation system. Many existing systems, such as global positioning system (GPS) and cellular communication systems, can be used to estimate vehicle location. The objective of wireless location is to determine the mobile station (MS) location in a wireless cellular communications system. The non-line-of-sight (NLOS) problem is the most crucial factor that it causes large measured error. In this paper, we present a novel positioning algorithm based on genetic algorithm (GA) to locate MS when three BSs are available for location purpose. Recently, GA are widely used as many various optimization problems. The proposed algorithm utilizes the intersections of three time of arrival (TOA) circles based on GA to estimate the MS location. The simulation results show that the proposed algorithms can really improve the location accuracy, even under severe NLOS conditions.

Investigation and Assessment of the Influence of Repairs on Transport System Operation Efficiency and Reliability

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地方都市交通機関の安全性・信頼性( 交通システムの安全性・信頼性)

地方都市交通機関の安全性・信頼性( 交通システムの安全性・信頼性)

A New Reliability and Cost-Benefit Integrated Optimization Model about Storage Bin in Materials Transportation System

The materials transportation system with storage bin is widely used in mines, power plants, material yards, and etc. Bin capacity size has great influence on reliability and production efficiency of whole materials transportation system. By utilizing some existing outcomes, this paper presents a new reliability and cost-benefit integrated optimization model about storage bin capacity in materials transportation system. Compared with some existed references, this presented model fully considers different influences of storage bin capacity on reliability and production efficiency of whole materials transportation system and realizes reliability, cost and benefit overall optimization decision. All kind of factors affecting designed storage bin capacity can be easily gotten by the presented model. In addition this paper also presents a set of detailed reliability and cost-benefit integrated optimization formulas about storage bin capacity in materials transportation system. These can offer the reference for capacity decision design computing of storage bin in materials transportation system.

Distribution-free travel time reliability assessment with probability inequalities

An assumption that pervades the current transportation system reliability assessment literature is that probability distributions of the sources of uncertainty are known explicitly. However, this distribution may be unavailable (inaccurate) in reality as we may have no (insufficient) data to calibrate the distribution. In this paper we relax this assumption and present a new method to assess travel time reliability that is distribution-free in the sense that the methodology only requires that the first N moments (where N is a user-specified positive integer) of the travel time to be known and that the travel times reside in a set of bounded and known intervals. Because of our modeling approach, all sources of uncertainty are automatically accounted for, as long as they are statistically independent. Instead of deriving exact probabilities on travel times exceeding certain thresholds via computationally intensive methods, we develop semi-analytical probability inequalities to quickly (i.e. within a fraction of a second) obtain upper bounds on the desired probability. Numerical experiments suggest that the inclusion of higher order moments can potentially significantly improve the bounds. The case study also demonstrates that the derived bounds are nontrivial for a large range of travel time values.

Inter-Vehicle Communications for Safety Driving Support : Access Schemes for High Density Terminal Environment(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

Inter-Vehicle Communications for Safety Driving Support : Access Schemes for High Density Terminal Environment(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

Labor-Saving Support for Super Eco-Ship : Safety and Labor-Saving(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

Labor-Saving Support for Super Eco-Ship : Safety and Labor-Saving(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

A Review of Reliability Studies in Transportation Engineering(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

A Review of Reliability Studies in Transportation Engineering(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

Risk-based Safety Management of Railway Systems(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

Risk-based Safety Management of Railway Systems(&lt;Special Survey&gt;Safety and Reliability of Transportation System)

Stochastic Simulation of Bus Traveling Time

The development of the city's public transport system has an indispensable role to alleviate the pressure of urban roads. Bus travel time reliability is an important evaluation index of the bus operation service level. The simulation of bus travel time helps us understand the reliability of bus running time. In this paper, we use Monte Carlo stochastic simulation method to calculate the reliability of bus travel time. On this basis, we establish a model of the reliability of public transportation systems to research the reliability of bus travel time.

Calculation of traffic flow breakdown probability to optimize link throughput

Traffic breakdown phenomenon is prevalent in empirical traffic system observations. Traffic flow breakdown is usually defined as an amount of sudden drop in traffic flow speed when traffic demand exceeds capacity. Modeling and calculating traffic flow breakdown probability remains an important issue when analyzing the stability and reliability of transportation system. The breakdown mechanism is still mysterious to practitioners and researchers in varying manner. Treating breakdown as a random event, this paper use discrete time Markov chain (DTMC) to model traffic state transition path, as a result, a transition probability matrix can be generated from empirical observations. From empirical analysis of breakdown, we found this formulation of breakdown probability follows the Zipf distribution. Therefore, a connection from traffic flow breakdown probability to how many vehicles are occupying a certain freeway segment (e.g. a link) will be established. Following from the results, a quantitative measure of breakdown probability can be obtained to optimize ramp metering rates to achieve optimum system performance measures.

Probabilistic Analysis of Transient Design for Water Supply Systems

Systematic transient analysis in water supply systems is intended to determine the reliability of water supply and the integrity of hydraulic devices when hydraulic transients (i.e., water hammers) occur. In the analysis, parameters such as wavespeed, pipe diameter, friction, and others, usually considered as known inputs in traditional water hammer models, are actually subject to uncertainties due to natural or human behaviors. The paper considers these uncertainties and investigates their effects on the reliability of water transportation systems and water supply networks under transient conditions with or without protection devices. In addition, the optimization of transient protection devices is also evaluated based on the probabilistic analysis. The results show that the probabilistic analysis method could inspect the influence of the different input uncertainties on the system responses under transient conditions and provide detailed information on the design for water supply systems and protection ...