Vehicle Positioning for Improving Road Safety

Abstract

Vehicle positioning is a key requirement for many safety applications. Active safety systems require precise vehicle positioning in order to assess the safety threats accurately, especially for those systems which are developed for warning/intervention in safety critical situations. When warning drivers of a local hazard (e.g. an accident site), accurate vehicle location information is important for warning the right driver groups at the right time. Global positioning system and digital maps have become major tools for vehicle positioning providing not only vehicle location information but also geometry preview of the road being used. Advances in wireless communication have made it possible for a vehicle to share its location information with other vehicles and traffic operation centres which greatly increases the opportunities to apply vehicle positioning technologies for improving road safety. This paper presents a state‐of‐the‐art review of vehicle positioning requirements for safety applications and vehicle positioning technologies. The paper also examines key issues relating to current and potential future applications of vehicle positioning technologies for improving road safety.     

Twenty Years of Rail Crowding Valuation Studies: Evidence and Lessons from British Experience

Abstract

This paper reviews evidence from British experience of the valuation of rail crowding obtained over 20 years from 17 studies. It summarizes these studies, places some useful empirical evidence in the public domain and draws lessons from this considerable body of evidence and experience. Crowding valuations, both for standing and seated in crowding conditions, are summarized in terms of time multipliers, which are inherently more transferable than monetary equivalents. A meta‐analysis of 208 valuations is reported, finding the valuations to vary with load factor and journey purpose. The seating multiplier averages 1.19 and the standing multiplier averages 2.32. The latter is in line with widely used multipliers applied to walking and waiting time. The most recent evidence is based around the number of standing passengers per square metre, thereby providing a more accurate measure of the discomfort of standing since, unlike load factor, it allows for the layout of the carriage and ease with which crowding can be accommodated. As far as methodology is concerned, the paper covers issues such as presenting crowding in ‘stated preference’ exercises and the realism of the crowding levels offered, non‐linearities in the relationship between crowding multipliers and the severity and amount of crowding time, and probabilistic versus deterministic representations of crowding. The paper also identifies future areas for research.     

本土汽车生产商面临挑战

在本届上海车展上,中国本土汽车生产商占据了4个展厅,全面展示了其在技术和研发方面的最新进展。为了应对日趋激烈的市场竞争和行业合并需求的增长,本土汽车生产商若想保持现在的市场份额,必将迎接更大的考验。