Evaluating marginal improvements to a transport network: An application to the Santiago underground

This paper describes a simplified methodology designed for quick investment appraisal of improvements to a transport network, and discusses its limitations and advantages particularly in the context of a developing country. The approach basically considers:

- a method to define the total population (relevant origin-destination pairs) affected by the project

- the selection of a low-cost background model to represent transport demand on a network at an aggregate level

- the choice of a suitable marginal demand model (in this case a discrete mode choice model) capable of providing the required sensitivity and accuracy to model the project

- the estimation of the marginal demand due to the project during all the years of the study horizon, and

- a sensitivity analysis to assess the robustness of the decision recommended using these two models.

Finally, the paper summarises the results of applying the methodology to the case of an extension to the Santiago underground; it was found that the project has a high social rate of return (almost 20 per cent). However, from the point of view of a private evaluation, it can cover its operating costs only.     

The experience of express coach deregulation in Great Britain

This paper reviews the effect of express coach deregulation in Britain following the Transport Act 1980. The authors have monitored the range of services offered before and after the Act, using operators' literature, roadside surveys, on-vehicle passenger interviews and interviews with operators as sources of information. These are used to present an overall picture of express deregulation, with particular reference to changes in real fare levels, and also the relative importance of competition within the coach industry compared with that of inter-modal competition (that between coach and rail). The latter has emerged as more significant.The greater part of the paper is devoted to analysis of the long-distance market but the development of commuter coach services into central London is also examined, together with the reasons why independent operators have secured a larger share of this market.     

Forced Steering of Rail Vehicles: Stability and Curving Mechanics

A forced steering rail vehicle employs linkages between.the carbody and wheelsets to force a more radial wheelset alignment. It is shown that the curve negotiation capability of forced steering trucks is significantly improved over conventional and self steering radial trucks. Parametric curves are presented showing angle-of-attack and lateral flange force as a function of steering gain parameters and truck bending stiffness. It is also shown that the forced steering concept can produce kinematic instability and severely reduced critical speeds for low conicities and creep coefficients. Analytic expressions are derived that illustrate how these kinematic instabilities can be avoided.     

Dynamic Response of a Six-axle Locomotive to Random Track Inputs

Spectral analysis techniques are employed to analyze the dynamic response of a six-axle locomotive on tangent track to vertical and lateral random track irregularities. The locomotive is represented by a thirty-nine (39) degrees of freedom model. A linear model is employed by considering small displacements, linear suspension elements and a linear theory for the wheel-rail interaction. Power spectral densities of displacements, velocities and accelerations and the statistical average frequencies of the system are obtained for each degree of freedom. Comparison of the calculated dominating frequencies with existing experimental values shows good agreement. The technique of spectral analysis is an effective tool for model validation, and for the determination of rail vehicle response to track irregularities. The probability functions for the response can be used as a measure for the ride quality of rail vehicles and for the study of fatigue damage of components.     

Maritime commercial malpractices and piracy under international law

The term 'Piracy' tends to be used in a loose, popular sense to refer to various acts of violence or lawlessness at sea which are not, strictly speaking, acts of piracy in law. In this article, the author examines the concept of piracy under international law and related notions such as hijacking and mutiny. In this context, he shows that the 'malpractices' of robber bands in such places as the inshore waters of Nigeria and The Philippines are not acts of piracy jure gentium.     

Directional Dynamics of a Tractor-Loader-Backhoe

This paper presents a study of the directional dynamics of large industrial tractors. These vehicles have special properties which make their dynamics interesting, including soft rear tires, large yaw moments of inertia and low or negative understeer gradients.

A linear yaw plane model was used for the analysis. The lateral compliance of the tires was included via a simplified version of the stretched-string model. Measurements were performed in support of the modeling effort, including inertial parameters, understeer gradient and transient response. A comparison between calculations and test results indicated that lateral compliance was an important influence on the transient response of these vehicles.     

Specification of a tour-based neighborhood shopping model

This paper presents a state-of-the practice neighborhood shopping travel demand model. The model structure is designed to incorporate decisions across five dimensions of shopping travel, including decisions of: (1) household tour frequency; (2) participating party; (3) shopping tour type; (4) mode, and (5) destination choices using a tour-based nested-logit model. As a neighborhood model, we have also captured the interrelated effects of three main factors associated with shopping travel decisions both within and outside of the neighborhood, including the residential location within the neighborhood, the neighborhood regional setting and the household structure. The model was validated using the travel data collected in three neighborhoods located in the Puget Sound region, WA. Results show that household socio-demographics have significant effects on the decisions for household tour frequency, mode and destination choices, while the characteristics of the traveling party have considerable impacts on the decisions for tour type. The level of service and the zone attractions influence decisions about mode and destination choices. The day of week variable (weekday versus weekend) is statistically significant in all models, indicating that weekday shopping travel decisions differ from weekend, across all five dimensions of interest. The paper concludes with a discussion about how the model can be used to examine policy-related neighborhood issues (e.g. accessibility).     

Research on the CTCS-4 Train Control System Based on Track Circuit Information FusionEI北大核心

Research purposes: CTCS-3 train control system is adopted in Chinese high-speed railway with speed of 300 km/h or higher. It is based on track circuit to check train occupancy and adopt quasi-moving block. In recent years, rapid development of national economy has put forward higher requirements for the capacity of high-speed railway. As a higher level train control system, CTCS-4 train control system can realize virtual block or moving block, and further shorten headway, but it is still in the stage of theoretical research. So this paper aims to analyze the characteristics of high-speed railway, and to propose a scheme for the implementation of CTCS-4 train control system based on track circuit fusion. Research conclusions:(1)When the wireless communication between vehicle and ground is interrupted, transport efficiency of CTCS-4 train control system can not meet the transport demand of high-speed railway.(2)CTCS-4 train control system should have the CTCS-2 backup function, which can make non-communication trains run normally and ensure the transport efficiency.(3)CTCS-4 train control system should integrate track circuit information, which can make RBC obtain position information of non-communication trains, improve the availability of the system and avoid complicated operational rules.(4)Due to complexity of high-speed railway and change of existing equipment, virtual block can be used in early stage of CTCS-4 train control system.(5)The research results can provide some references for CTCS-4 train control system in high-speed railway. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.