Advancing road safety analysis: new methods for evaluating and measuring safety

减少道路碰撞造成的社会和经济代价的重要性怎么强调都不为过。因此，最近进行了大量的研究，在道路安全分析方面也取得了进展。这些发展正在推动在道路规划和设计中明确考虑安全的运动。然而，与这些进步相关的是一系列阻碍道路安全未来发展的障碍。对于碰撞因素之间的复杂相互作用以及安全措施是如何发挥作用的，缺乏完整的理解。这项研究的主要贡献将是开发新的方法来促进这一理解。这项建议侧重于三个问题：i)评估和验证替代安全措施；ii)使用可靠性方法校准道路设计规范，并建立与碰撞的联系；iii)解决与干预效果评估有关的关键问题。这项研究试图从几个方面为交通安全研究做出贡献。它测试和验证了交通冲突作为替代安全措施的使用。这将解决交通冲突技术的主要缺点，导致碰撞替代品的使用被更广泛地接受，并提供对车辆碰撞故障机理的更好理解，特别是驾驶员的避碰行为，这将有助于安全问题的诊断和补救。此外，研究还应通过建立可靠性指标与预期碰撞频率之间的关系，并提供确保一致和可接受的风险水平的道路设计标准，使可靠性分析在道路设计中得到更广泛的应用。最后，这项研究将为道路安全干预分析开发新的方法，从而更好地理解模型参数的作用及其对治疗效果估计的影响。目前的评估技术假定应对措施的有效性不随时间而改变，这是不现实的。考虑到未来收益折现到现值的方式，使用随时间变化的对策有效性的结果可能会显著影响安全措施的成本有效性。

The importance of reducing the social and economic costs of road collisions cannot be overstated. Therefore, considerable research has been undertaken recently and advances have been made in road safety analysis. These developments are creating a movement towards the explicit consideration of safety in road planning and design. However, associated with these advances are a series of obstacles that are inhibiting the future direction of road safety. There is a lack of complete understanding of the complex interaction of collision factors and how safety measures work. The main contribution of this research will be the development of novel methods that advance this understanding. This proposal focuses on three issues: i) evaluating and validating surrogate safety measures; ii) calibrating road design codes using reliability methods and establishing linkage with collisions and iii) addressing key issues related to the evaluation of intervention effectiveness. The research attempts to contribute to traffic safety research in several ways. It tests and validates the use of traffic conflicts as surrogate safety measures. This should address the main shortcomings of the traffic conflict technique, lead to a wider acceptance of the use of collision surrogates, and offer a better understanding of vehicle collision failure mechanism, particularly the collision-avoidance behavior of drivers which should help the diagnosis and remedy of the safety problems. As well, the research should lead to a wider application of reliability analysis in road design through establishing relationships between the reliability index and the expected collision frequency and providing road design standards that ensure a consistent and accepted risk levels. Finally, the research will develop novel methods for road safety intervention analysis that provide better understanding of the role of model parameters and their effects on the estimation of treatment effectiveness. Current evaluation techniques assume constant countermeasure effectiveness that does not change with time which is unrealistic. Given the way future benefits are discounted to present values, the results of using countermeasure effectiveness which changes with time can significantly impact the cost effectiveness of safety measures.