Advancing performance-based highway geometric design

*公路几何设计的传统方法依赖于遵守主要基于经验数据的标准，这些标准将驾驶员/车辆性能与几何特征(标称安全)联系起来。可以接受的绩效被认为是通过正确应用技术指导而产生的，但它仍然是产生物理设计尺寸的过程的间接结果。最近，设计师们开始认识到，设计应该基于实际性能，包括碰撞体验(实质性安全)、机动性和成本。基于性能的几何设计已被零星地应用于可靠性分析、价值工程和基于上下文的设计等概念。它还得到了几个最新发展的帮助，最著名的是交互式公路安全设计模型、公路安全手册和路边安全分析程序。这些发展为设计者提供了比传统方法更好的分析工具。然而，由于两个知识差距，它们通常侧重于单一的业绩衡量：(1)一些业绩衡量没有得到很好的理解，也没有被量化；(2)缺乏同时考虑所有相关业绩衡量的综合方法。认识到业绩衡量之间的根本相互作用，意味着需要更正式和更全面的工具，以协助在实践中更广泛地执行。这一需求已经得到了研究人员和实践者的认可。拟议的研究解决了对两种类型公路设施的需求：正在成为可行的十字路口类型的环形交叉路口，以及在公路网中分担相当大比例撞车的农村双车道公路。对于每个高速公路设施，拟议研究的目标是首先建立相关性能衡量标准的模型，然后将其整合到多目标决策支持系统中。*这项研究将启动前所未有的努力，建立强大、全面的决策支持系统，直接将相关绩效衡量标准纳入设计过程本身，而不是像今天这样以外部方式。因此，这些系统将保证具有成本效益的解决方案，并将不可避免地产生不同地点的道路设计，反映出当地环境、项目目标和相对价值的差异。这项研究将促进其他公路设施(如农村多车道公路和信号交叉口)和其他道路使用者(如骑自行车的人和行人)的PB设计的继续发展。开发的决策支持系统将使从业者能够比较关键的设计权衡，并做出更明智的决定。拟议的研究报告是及时和创新的，这将有助于提高加拿大公路设计研究的声誉。**

***The conventional approach to highway geometric design relies on adherence to criteria based mainly on empirical data that relate driver/vehicle performance to geometric characteristics (nominal safety). Acceptable performance is presumed to be produced through proper application of the technical guidance, but is nonetheless an indirect outcome of the process, which produces physical design dimensions. Recently, designers have begun to recognize that design should be based on actual performance, including crash experience (substantive safety), mobility, and cost. Performance-based (PB) geometric design has been sporadically applied using such concepts as reliability analysis, value engineering, and context-based design. It has also been aided by several recent developments, most notably Interactive Highway Safety Design Model, Highway Safety Manual, and Roadside Safety Analysis Program. These developments provide designers with better analysis tools than the conventional approach. However, they generally focus on single performance measures because of two knowledge gaps: (1) some performance measures are not well understood and have not been yet quantified and (2) a comprehensive methodology that simultaneously considers all relevant performance measures is lacking. Recognition of the fundamental interactions among performance measures implies the need for more formal and comprehensive tools to aid broader implementation in practice. This need has been recognized by researchers and practitioners. The proposed research addresses this need for two types of highway facilities: roundabouts that are emerging as viable intersection type and rural two-lane highways that share a substantial proportion of crashes in the highway network. For each highway facility, the objective of the proposed research is first to model relevant performance measures and then to integrate them in a multi-objective decision-support system.***This research will initiate unprecedented efforts in building strong, comprehensive decision-support systems that directly incorporate relevant performance measures within the design process itself, rather than in an external manner, as is the case today. As such, these systems would guarantee cost-effective solutions and would inevitably produce roadway designs that differ from one location to another, reflecting differences in local context, project objectives, and relative values. The research will promote continued development of PB design for other highway facilities (eg, rural multi-lane highways and signalized intersections) and for other road users (eg, bicyclist and pedestrians). The developed decision-support systems will enable practitioners to compare key design trade-offs and make better informed decisions. The proposed research is timely and innovative, and  will aid the reputation of Canadian highway design research.**