The concept of delay

The word delay is so widely used that it may be assumed to be a simple concept which is well understood. It is taken to be a name for wasted time on a journey, but attempts to quantify it in order to use it as a measure of performance of a transportation facility have not given complete satisfaction. Drivers are observed to behave in ways which reveal attitudes to wasted time which differ from those of the researcher. These problems have been reported in many studies but do not seem to have been pursued.This paper discusses the concept of delay. A basic definition leads to problems of measurement which suggest alternative definitions which have more apparent relevance to traffic networks in which more than one cause of delay is of interest. Further speculation about these definitions points to the fact that delay can be either of two separate concepts.In conclusion it is argued that delay should no longer be regarded as an objective quantity capable of direct measurement. Instead of delay being thought the cause of driver annoyance, it should be taken that it is the existence of driver frustration which converts time lost into delay. It is better to define delay as unwanted journey time.     

On nonlinear ship waves and wave resistance calculations

A finite difference method based on the Euler equations is developed for computing ship waves and wave resistances. Time marching is carried out using a time-splitting fractional-step method. The second-order central difference is used to discretize the spatial differentials, while the convection terms are discretized by the QUICK scheme. A body- and free-surface-fitted grid system with a cell-centered stencil is used. A Poisson equation for the pressure increment at each time step is solved to enforce mass conservation. The method is validated by comparing the numerical results with the experimental data for a Wigley parabolic hull. The characteristics of ship waves, such as the wave profile along the hull, the wave pattern on the free surface, the pressure distribution on the hull surface, and the wave-making resistance are reasonably predicted. The calculated results are in good agreement with the experimental data. Received for publication on Oct. 13, 1998; accepted on Jan. 20, 1999     

An investigation of multiplier effects generated by implementing queue jump lanes at multiple intersections

This paper investigates the combination effects of queue jump lanes (QJLs) on signalised arterials to establish if a multiplier effect exists, that is, the benefit from providing QJLs at multiple intersections is higher than the sum of benefits from providing them individually at each of those intersections. To explore the combination effects on bus delay and total person delay, a delay estimation model is developed using kinematic wave theory, kinematic equations and Monte Carlo simulation. In addition, to investigate the combination effects in offset settings optimised for bus delay or total person delay, offset optimisation models are proposed. Validation results using traffic micro‐simulation indicate the effectiveness and computational efficiency of the proposed models. Results of a modelling test bed suggest that providing QJLs at multiple intersections can create a multiplier effect on one‐directional bus delay savings with signal offsets that provide bus progression. Furthermore, optimising offsets to minimise bus delay tends to create a multiplier effect on one‐directional bus delay savings, particularly when variations in dwell times are not high. The reason for the multiplier effect may be that providing QJLs reduces variations in bus travel times, which makes signal coordination for buses perform more effectively. From a policy perspective, the existence of a multiplier effect suggests that a corridor‐wide scale implementation of QJLs has considerable merit. Copyright © 2016 John Wiley & Sons, Ltd.     

Do new sources of traffic data make the application of Chaos Theory to traffic management a realistic possibility?

Current signal systems for managing road traffic in many urban areas around the world lack a coordinated approach to detecting the spatial and temporal evolution of congestion across control regions within city networks. This severely inhibits these systems’ ability to detect reliably, on a strategic level, the onset of congestion and implement effective preventative action. As traffic is a time-dependent and non-linear system, Chaos Theory is a prime candidate for application to Urban Traffic Control (UTC) to improve congestion and pollution management. Previous applications have been restricted to relatively uncomplicated motorway and inter-urban networks, arguably where the associated problems of congestion and vehicle emissions are less severe, due to a general unavailability of high-resolution temporal and spatial data that preserve the variability in short-term traffic patterns required for Chaos Theory to work to its full potential. This paper argues that this restriction can now be overcome due to the emergence of new sources of high-resolution data and large data storage capabilities. Consequently, this opens up the real possibility for a new generation of UTC systems that are better able to detect the dynamic states of traffic and therefore more effectively prevent the onset of traffic congestion in urban areas worldwide.     

Hazard perception test development for Lithuanian drivers

Hazard perception tests may not be transferable between different countries, due to differences in traffic culture and infrastructure. Therefore, different instruments might be necessary for assessing hazard perception in various countries. The aim of the current study was to develop the Lithuanian hazard perception test based on static traffic images and test its psychometric properties. Thirty-four experienced drivers participated in a pilot study, and 125 drivers with diverse driving experience took part in the main study. The final test contained 27 static traffic scenes and the participants were asked to respond if they saw a hazard or not. Results demonstrated that the test has satisfactory internal consistency and test-retest reliability. It differentiated between inexperienced and experienced drivers, and between those experienced drivers who had less than three or more than three crashes in their driving history. The test has sufficient psychometric properties for research; still further development is needed in order to apply it for individual testing and decisions about licence provision.     

Application of fuzzy theory for identifying the required availability of an autonomous localization unit in European Train Control System

According to the evolution tendency of the control decision process from a trackside to a train-borne system, various autonomous localization units for railway vehicles were developed. As recommended in railway standards, the design process of each system, here the autonomous localization units (LU), follows the V-model whose first step is to define its availability requirement in order to satisfy the global ETCS system requirements. The classical approach for assigning the subsystem availability is based on the assumption that failure parameters of other units are precisely known. This assumption is too restricted in reality due to the lack of information. In this paper, we propose a new approach that allows taking into account uncertainties in the dependability parameters of the ETCS components for identifying the upper threshold of the LU unavailability to reach ETCS availability requirements. Using fuzzy fault trees, the fuzzy unavailability of the ETCS without the autonomous LU is evaluated. Then, based on its membership function, we assess the satisfaction rate that an advanced ETCS with the autonomous LU can satisfy the ETCS availability target.     

采用自动识别系统对水下输气管线、离岸平台和船舶检验评分的实时监测（英文）

The aim of this research is to develop an algorithm and application that can perform real-time monitoring of the safety operation of offshore platforms and subsea gas pipelines as well as determine the need for ship inspection using data obtained from automatic identification system(AIS). The research also focuses on the integration of shipping database,AIS data, and others to develop a prototype for designing a real-time monitoring system of offshore platforms and pipelines. A simple concept is used in the development of this prototype, which is achieved by using an overlaying map that outlines the coordinates of the offshore platform and subsea gas pipeline with the ship's coordinates(longitude/latitude) as detected by AIS. Using such information, we can then build an early warning system(EWS) relayed through short message service(SMS), email, or other means when the ship enters the restricted and exclusion zone of platforms and pipelines. The ship inspection system is developed by combining several attributes. Then, decision analysis software is employed to prioritize the vessel's four attributes, including ship age, ship type, classification, and flag state.Results show that the EWS can increase the safety level of offshore platforms and pipelines, as well as the efficient use of patrol boats in monitoring the safety of the facilities. Meanwhile, ship inspection enables the port to prioritize the ship to be inspected in accordance with the priority ranking inspection score.     

Real-time Monitoring of Subsea Gas Pipelines,Offshore Platforms,and Ship Inspection Scores Using an Automatic Identification System

The aim of this research is to develop an algorithm and application that can perform real-time monitoring of the safety operation of offshore platforms and subsea gas pipelines as well as determine the need for ship inspection using data obtained from automatic identification system (AIS). The research also focuses on the integration of shipping database, AIS data, and others to develop a prototype for designing a real-time monitoring system of offshore platforms and pipelines. A simple concept is used in the development of this prototype, which is achieved by using an overlaying map that outlines the coordinates of the offshore platform and subsea gas pipeline with the ship’s coordinates (longitude/latitude) as detected by AIS. Using such information, we can then build an early warning system (EWS) relayed through short message service (SMS), email, or other means when the ship enters the restricted and exclusion zone of platforms and pipelines. The ship inspection system is developed by combining several attributes. Then, decision analysis software is employed to prioritize the vessel’s four attributes, including ship age, ship type, classification, and flag state. Results show that the EWS can increase the safety level of offshore platforms and pipelines, as well as the efficient use of patrol boats in monitoring the safety of the facilities. Meanwhile, ship inspection enables the port to prioritize the ship to be inspected in accordance with the priority ranking inspection score.     

IP MULTICAST GROUP MANAGEMENT FOR BROADCAST LANS DISTRIBUTION

IntroductionThere are two traditional types of communica-tion in computer networks:unicastand broadcast.A unicast address (one to one) is designed to sendmessages to a single destination in a network.Abroadcast (one to all) address is used to send datato the entire network(all hosts) .Multicast(oneor many to many) can be viewed either as an inter-mediate case,or as a generalized mode encompass-ing both unicast and broadcast as special cases.Inmulticast mode,messages are sent to an arbitraryse…     

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研究印度城市道路上设置公交专用道后小汽车出行向公交转移的可能性. 借助新的混合交通流仿真模型测定设置公交专用道后公交服务水平改善状况. 基于陈述偏好入户调查的抽样数据,本文还引入其他影响出行方式转移的变量,标定出行方式选择二元Logit模型. 根据实际和预测数据,确定了公交服务水平改善条件下小汽车出行向公交转移的一系列主要影响因素. 基于两种方式出行时间差,绘制出行方式转换概率曲线,并为多变量宽值域条件下交通方式转移的预测提供一种易于操作的方法.