A novel method to model wheel–rail normal contact in vehicle dynamics simulation

An approximate analytical method is proposed for calculating the contact patch and pressure distribution in the wheel–rail interface. The deformation of the surfaces in contact is approximated using the separation between them. This makes it possible to estimate the contact patch analytically. The contact pressure distribution in the rolling direction is assumed to be elliptic with its maximum calculated by applying Hertz' solution locally. The results are identical to Hertz's for elliptic cases. In non-elliptic cases good agreement is achieved in comparison to the more accurate but computationally expensive Kalker's variational method (CONTACT code). Compared to simplified non-elliptic contact methods based on virtual penetration, the calculated contact patch and pressure distribution are markedly improved. The computational cost of the proposed method is significantly lower than the more detailed methods, making it worthwhile to be applied to rolling contact in rail vehicle dynamics simulation. Such fast and accurate estimation of contact patch and pressure paves the way for on-line modelling of damage phenomena in dynamics simulation packages.     

Education influence in traffic safety: A case study in Vietnam

It is well known that traffic accidents are of high importance to the public health spectrum around the world. Moreover, in developing countries such as Vietnam, the mortality rate from road traffic accidents is rather high in comparison with other Southeast Asian countries. Not only do the majority of the people killed and seriously injured significantly affect the quality of life of the citizens, but traffic accidents also negatively impact a nation's economic and social development. Statistics show that far more people are injured or die in traffic accidents than are afflicted by any of the most serious diseases. The very high occurrence of traffic accidents in Vietnam has become one of the country's major social issues. The importance of human factors in transport policy discussion is growing. There is a realization that policy options that appear beneficial in principle have to be checked for their feasibility of implementation. Understanding and describing driver behavior become a challenge when one tries to identify driver errors in determining accident/conflict causal factors and countermeasures.In recent years, having understood the serious effects of traffic accidents on society at large, scientific researchers, traffic engineers and policy makers in Vietnam have developed many projects and conducted research in the field of traffic safety. The human factor is also considered to be the central element in the whole system. The final goal is to organize a traffic environment that is convenient and safe for road users.This article explains the application of the risk analysis approach in evaluating influences of education and enforcement in traffic safety.     

Exploring paratransit service quality based on low-income women's perception: A case study in Dhaka city by structural equation model (SEM)

In developing countries paratransit plays a vital role as a public transport mode since mass transit system is inadequate. This research investigates low-income working womens satisfaction level on various service features of paratransit modes based on their experience. Structural Equation Model (SEM) was employed to capture low-income working women's perceptions of paratransit service quality (SQ) in Dhaka city, Bangladesh. Achieving the study objective, a questionnaire survey was conducted on existing paratransit routes from Kamrangichor and Jhauchor slum areas where no bus service is available. Total 410 regular paratransit users who usually use this mode getting to and from workplace participated in the survey during July 2018. To evaluate the paratransit SQ the passengers were asked to rate their perception about 22 service attributes on a likert scale of five points. A series of SEMs were developed to explore the relationship of service features for the overall paratransit SQ. Among the five models the best one is selected by different goodness-of-fit values (CFI = 0.82, TLI = 0.79, RMSEA = 0.12, SRMR = 0.059, AIC = 18,666.94). Model 5 is the best structure developed with four latent variables: ‘Service feature’, ‘System performance’, ‘Safety and security’ and ‘Reliability’ This research explores that ‘Security of goods’, ‘Security of passengers’, ‘Movement flexibility in any road’, ‘Travel expenditure compared to other transport’, and ‘Quality of driver’ are 1st, 2nd, 3rd, 4th and 5th most significant variables that impact on the SQ positively, which represents the real scenario. The outcomes of this research might assist operators and policymakers in formulating policies to enhance urban paratransit SQ.