关注铁路产品过程能力风险 提高质量管理体系有效性和效率

论述了关注铁路产品过程能力风险的必要性,主张在过程能力管理中积极应用过程能力指数方法,准确理解确认过程中为过程的评审和批准所规定的准则,扩展确认过程的范围,通过强化过程能力管理,提高质量管理体系的有效性和效率。     

From behavioral psychology to acceleration modeling: Calibration,validation, and exploration of drivers’ cognitive and safety parameters in a risk-taking environment

We investigate a utility-based approach for driver car-following behavioral modeling while analyzing different aspects of the model characteristics especially in terms of capturing different fundamental diagram regions and safety proxy indices. The adopted model came from an elementary thought where drivers associate subjective utilities for accelerations (i.e. gain in travel times) and subjective dis-utilities for decelerations (i.e. loss in travel time) with a perceived probability of being involved in rear-end collision crashes. Following the testing of the model general structure, the authors translate the corresponding behavioral psychology theory – prospect theory – into an efficient microscopic traffic modeling with more elaborate stochastic characteristics considered in a risk-taking environment.After model formulation, we explore different model disaggregate and aggregate characteristics making sure that fidelity is kept in terms of equilibrium properties. Significant effort is then dedicated to calibrating and validating the model using microscopic trajectory data. A modified genetic algorithm is adopted for this purpose while focusing on capturing inter-driver heterogeneity for each of the parameters. Using the calibration exercise as a starting point, simulation sensitivity analysis is performed to reproduce different fundamental diagram regions and to explore rear-end collisions related properties. In terms of fundamental diagram regions, the model in hand is able to capture traffic breakdowns and different instabilities in the congested region represented by flow-density data points scattering. In terms of incident related measures, the effect of heterogeneity in both psychological factors and execution/perception errors on the accidents number and their distribution is studied. Through sensitivity analysis, correlations between the crash-penalty, the negative coefficient associated with losses in speed, the positive coefficient associated with gains in speed, the driver’s uncertainty, the anticipation time and the reaction time are retrieved. The formulated model offers a better understanding of driving behavior, particularly under extreme/incident conditions.     

Survivability of an ocean patrol vessel – Analysis approach and uncertainty treatment

Military ocean patrol vessels (OPVs) are today an increasingly common type of naval ship. To facilitate the wide range of tasks with small crews, OPVs represent several ship design compromises between, for example, survivability, redundancy and technical endurance, and some of these compromises are new to military ships.The aim of this study is to examine how the design risk control-options in relation to survivability, redundancy and technical endurance can be linked to the operational risk in a patrol and surveillance scenario. The ship operation for a generic OPV, including the actions of the threat, is modelled with a Bayesian network describing the scenario and the dependency among different influences.The scenario is described with expert data collected from subject matter experts. The approach includes an analysis of uncertainty using Monte Carlo analysis and numerical derivative analysis.The results show that it is possible to link the performance of specific ship design features to the operational risk. Being able to propagate the epistemic uncertainties through the model is important to understand how the uncertainty in the input affects the output and the output uncertainty for the studied case is small relative to the input uncertainty. The study shows that linking different ship design features for aspects such as survivability, redundancy and technical endurance to the operational risk gives important information for the ship design decision-making process.     

A bi-objective bi-level signal control policy for transport of hazardous materials in urban road networks

A bi-objective bi-level signal control optimization for hazardous material (hazmat) transport is considered to assess trade-offs between travel cost and environment impacts such as public risk exposure. A least maxi-sum risk model with explicit signal delay is presented to determine generalized travel cost for hazmat carriers. Since the bi-level signal control problem is generally a non-convex program, a bundle method using generalized gradients is proposed. A bounding strategy is developed to stabilize solutions of the bi-level program and reduce relative gaps between iterations. Numerical comparisons are made with other risk-averse models. The results indicate that the proposed bi-objective bi-level model becomes even amiable to signal control policy makers since provides flexible solutions whilst is acceptable to carriers since takes account of travel delay at signal-controlled junctions. Moreover, the trade-offs between public risk and generalized travel costs are empirically investigated among different risk models with a variety of weights. As a result, the proposed model consistently exhibits highly considerable advantage on mitigation of public risk whilst incurred less cost loss as compared to other alternatives.     

Infrastructure based approach for roadway departure risk assessment

This paper presents a warning device to prevent the roadway departure of light vehicles while cornering. The proposed risk assessment methodology is based on recent works from the authors (Rey et al., 2011b,a; Rey, 2010). Given the random variability arising from the driver, the vehicle and the infrastructure at the entrance to the curve, a probabilistic strategy is adopted to assess the roadway departure risk. The infrastructure-based methodology enables the real curve characteristics to be considered and an alarm triggering decision to be made. Two safety criteria are tested and the potential safety benefits of the proposed warning device are evaluated. Contrary to existing roadway departure warning systems, the proposed approach does not require extra equipment for vehicles; it only requires that the measuring and warning devices be part of the road infrastructure, which is a great advantage in terms of economic cost.     

后亚运时期广州交通规划治堵工作的思考

交通拥堵已经成为国内城市普遍的一种城市病,广州借举办亚运之机,交通基础设施发生了根本性的变化,但仍然面临着交通拥堵的压力。在总结以往经验的同时,对形成拥堵的主要原因进行了分析,通过交通规划模型的迭代分析和风险评估,提出了3个方面的交通整治措施建议及2020年小汽车的合理规模,辨明了广州交通的发展阶段。最后,还对下一步的工作提出了建议。     

Embedding risk attitude and decision weights in non-linear logit to accommodate time variability in the value of expected travel time savings

In recent years we have seen important extensions of logit models in behavioural research such as incorporation of preference and scale heterogeneity, attribute processing heuristics, and estimation of willingness to pay (WTP) in WTP space. With rare exception, however, a non-linear treatment of the parameter set to allow for behavioural reality, such as embedded risk attitude and perceptual conditioning of occurrence probabilities attached to specific attributes, is absent. This is especially relevant to the recent focus in travel behaviour research on identifying the willingness to pay for reduced travel time variability, which is the source of estimates of the value of trip reliability that has been shown to take on an increasingly important role in project appraisal. This paper incorporates, in a generalised non-linear (in parameters) logit model, alternative functional forms for perceptual conditioning (known as probability weighting) and risk attitude in the utility function to account for travel time variability, and then derives an empirical estimate of the willingness to pay for trip time variability-embedded travel time savings as an alternative to separate estimates of time savings and trip time reliability. We illustrate the richness of the approach using a stated choice data set for commuter choice between unlabelled attribute packages. Statistically significant risk attitude parameters and parameters underlying decision weights are estimated for multinomial logit and mixed multinomial logit models, along with values of expected travel time savings.     

铁路隧道风险评估若干问题探讨

文章探讨了当前隧道风险评估中存在的隧道初始和残余风险综合等级判定准则的不统一、施工阶段风险评估中风险因素的缺失及初步设计阶段风险评估"谈虎色变"、施工阶段风险评估"避轻就重"等问题,提出了解决这些问题的对策,即初始和残余风险综合等级就高准则、隧道施工阶段快速适时风险评估和特殊地区隧道初始风险等级合理确定等。     

Safety-oriented bicycling and traffic accident involvement

Many U.S. bicyclists are killed or injured in traffic accidents annually. Based on analysis of available research and published reports on traffic accidents, it was theorized that adherence to six safety-oriented on-road bicycling practices will reduce involvement in traffic accidents. This study investigated whether adherence to these safety-oriented bicycling practices is associated with reduced involvement in traffic accidents. U.S. adult bicycle riders responded to an anonymous on-line survey covering bicycling practices, recent traffic accident experiences, and potential confounding variables. Participants were recruited via on-line announcements to bicycling-related organizations. The results suggested that neither vigilance nor cautiousness will protect adult bicycle riders from traffic accident involvement, but predictability might reduce accident risk, particularly for younger adults. Results should be interpreted cautiously due to limitations in the study methodology. Further research of this type is warranted.This paper is a re-formulation of research originally presented as a conference paper and oral presentation at the International Cycling Safety Conference in Bologna, Italy, 3–4 November 2016.     

Energy-Based Approach to Structural Robustness

Introduction Structures must be robust, so that after accidentaldamage, they will not suffer consequences dispropor-tionate to the original causes. In structural engineer-ing, the modern research on structural robustness maydate back to the progressive collapse of the RonanPoint in England in 1968, where a relatively weakexplosion led to a disproportionate failure ( seeFig.1). Following this accident, considerable at-tempts have been made on this subject though debatecontinues about the true…