Impact of information technology on public transport fares data

The work described was undertaken as part of the CASSIOPE project in the EC DRIVE programme. A range of fare collection procedures in public transport is described, and the importance of these for data collection by operators is stressed. It is suggested that such data management could be standardized and to this end four case studies were carried out in different European cities. Data models were built for each city, and these models are merged into a preliminary version of a generalized model. The need and uses for such a fare collection data model is explained.     

Mathematical Modelling of Vibrations and Loading of Railway Tanks Taking into Account the Liquid Cargo Mobility

Dynamics and loading of railway tank cars transporting liquid cargo are investigated. The approach based on the mechanical-pendulum analogy for the liquid cargo mobility simulation is proposed. Hydrodynamic parameters of the mechanical analogy are determined using the solution of the boundary-value problem for the liquid cargo vibrations in a cavity with the tank boiler shape. The fitting of the developed mathematical models is proved by comparison of calculated results and test data. Vibration characteristics and loading of tank-cars under their shunt collisions and motion along straight and curved track in trains are evaluated. It is shown that as a rule the liquid cargo mobility has an essential influence on tank dynamic properties.     

The dynamics of traffic assignment and traffic control: A theoretical study

The paper considers traffic assignment, with traffic controls, in an increasingly dynamic way. First, a natural way of introducing the responsive policy, P_o, into steady state traffic assignment is presented. Then it is shown that natural stability results follow within a dynamical version of this static equilibrium model (still with a constant demand). We are able to obtain similar stability results when queues are explicitly allowed for, provided demand is constant. Finally we allow demand to vary with time; we consider the dynamic assignment problem with signal-settings now fixed. Here we assume that vehicles are very short and that deterministic queueing theory applies, and show that the time-dependent queueing delay at the bottleneck at the end of a link is a monotone function of the time-dependent input profile to the bottleneck. We have been unable to obtain results when dynamic demand and responsive signal control are combined.     

A dynamic stochastic assignment model for the analysis of general networks

The paper adopts the framework employed by the existing dynamic assignment models, which analyse specific network forms, and develops a methodology for analysing general networks. Traffic conditions within a link are assumed to be homogeneous, and the time varying O-D travel times and traffic flow patterns are calculated using elementary relationships from traffic flow theory and link volume conservation equations. Each individual is assumed to select a departure time and a route by trading off the travel time and schedule delay associated with each alternative. A route is considered as reasonable if it includes only links which do not take the traveller back to the origin. The set of reasonable routes is not consistant but depends on the time that an individual decides to depart from his origin. Equilibrium distributions are derived from a Markovian model which describes the evolution of travel patterns from day to day. Numerical simulation experiments are conducted to analyse the impact of different work start time flexibilities on the time dependent travel patterns. The similarity between link flows and travel times obtained from static and dynamic stochastic assignment is investigated. It is shown that in congested networks the application of static assignment results in travel times which are lower than the ones predicted by dynamic assignment.     

Effect of fatigue strain range on properties of high-strength structural steel

Ship hulls are built with stiffened steel plates and experience continuous fatigue load cycles when in service. Mechanical properties of the steel are expected to change due to the application of these cyclic loads. Therefore, the mechanical properties of the material at various levels of fatigue damage need to be understood. This paper presents two test series that were conducted to determine the effect of two different strain ranges (2000 and 3000 micro strains) of fatigue cycles on the mechanical properties of high-strength structural steel. The test results indicate that the cycle-dependent behaviours of the material can cause a slight increase or a significant decrease in the yield strength when compared to its virgin state. However, the ductility of the steel does not change much as the strain cycle increases.     

Effects of information in road transport networks with recurrent congestion

This paper aims to gain more insight into the implications of information provision to drivers on the performance of road transport networks with recurrent congestion. For this purpose, a simulation program consisting of three components has been written. The first component is the traffic simulation model, the second component is the information provision mechanism, and the third component monitors the behavioural decision-making process of the drivers, which is modelled using a utility-based satisficing principle. Three types of information provision mechanisms will be considered: information based upon own-experience, after-trip information and real-time en route information. The findings in this paper, obtained in a hypothetical context, underline the important relationship betweenoverreaction, thelevel of market penetration and thequality of the information. High quality information allows a high level of market penetration, while low quality information, even when provided at low levels of market penetration, induces overreaction. Furthermore, real-time en route information is in particular beneficial during the process leading to a steady state; it reduces the variance in travel time considerably. The paper concludes with a discussion on the market potential of motorist information systems when commercially marketed.     

Reliability assessment of maintained ship hulls with correlated corroded elements

This paper reviews the factors that affect the corrosion rate of the ship hull girder. It is shown that corrosion rates vary as a function of the location of the element in the structure, of the ocean area and type of ballast tank and steel. However, the corrosion rate in elements that are subjected to similar conditions is highly correlated.

A time-variant formulation is proposed including the correlation between the corrosion rates in neighbouring elements in modelling the degrading effect that corrosion has on the reliability of ship hulls. The effect of corrosion is represented as a time-dependent decrease of plate thickness that affects the midship section modulus. One repair policy was considered and the example results show the effect of plate replacement when its thickness reaches 75% of the original value. The results also illustrate how the limit value of the thickness in the repair criteria influences the reliability and the decision about repair actions. This is also shown for the effect of different corrosion rates, inspection intervals, and allowable stresses.     

Wave impact on a horizontal elastic plate

The objective is to find slamming-induced local stresses in the steel or aluminum wetdeck of a multihull vessel. This is studied theoretically by representing the wetdeck as a beam model and accounting for dynamic hydroelastic effects. Two numerical methods are used, one being a simplified asymptotic solution. Satisfactory agreement between the two methods is reported. Experimental drop tests of horizontal elastic plates of steel and aluminum are also reported, and the results from the experiments agree well with the numerical computations. This study reveals, both numerically and experimentally, that slamming-induced local stresses are strongly influenced by dynamic hydroelastic effects. The maximum bending stresses are insensitive to where waves hit, the curvature of the waves, and maximum pressures. Measured maximum pressures are very sensitive to external conditions, and cannot be used as a measure of maximum local bending stresses. A simple procedure for local design stresses due to wetdeck slamming is outlined.