Abstract Accessibility is widely thought the most appropriate reference point when assessing transport inequality, a fundamental consideration of the liveable city. But definitions of accessibility vary and often either trivialise or overcomplicate the concept, with the result that decision makers lack a representation of it that is sufficiently accurate and at the same time sufficiently straightforward. A response is offered in this paper: the Index of Personal Travel Impact (IPTI). IPTI is an estimate at the individual level of the relative impact of desired travel, reflecting the time taken and real financial effect, and is expressed as an amount per unit distance. It is calculated using the journeys an individual would like to make (as opposed to those they actually make or those that an authority might assume “important”) and reflects the specific characteristics of the individual (e.g. car availability or mobility impairment) and of the journey (e.g. the need to arrive by a given time). It therefore serves as a good individual-level representation of the relative ease/difficulty of travelling. The rationale for IPTI's formulation is described in detail and the measure's strengths and weaknesses discussed. The practical feasibility of calculating IPTI is explored through description of a small pilot which produced encouraging results, and through a discussion of the potential efficiencies offered by the increasing availability of large data sources and online journey-planning tools. IPTI's potential applications are then discussed: first, it could provide an intelligible way of demonstrating the differing extent to which people face mobility barriers, which could be useful where an attempt is being made to address inequality. Second, IPTI could inform the appraisal process by showing the distributional effects of a given scheme upon individuals' relative capacity to travel. The paper concludes with recommendations for further research.

中文翻译：

---

解决交通不平等的工具：可达性衡量的新变体

摘要 在评估交通不平等时，人们普遍认为可达性是最合适的参考点，交通不平等是宜居城市的一个基本考虑因素。但是可访问性的定义各不相同，并且常常使概念变得琐碎或过于复杂，结果决策者缺乏足够准确同时又足够直接的表示。本文提供了一个回应：个人旅行影响指数 (IPTI)。IPTI 是在个人层面对所需旅行的相对影响的估计，反映了所花费的时间和实际财务影响，并以每单位距离的金额表示。它是使用个人想要的旅程（而不是他们实际进行的旅程或当局可能认为“重要”的旅程）计算的，并反映了个人的具体特征（例如汽车可用性或行动障碍）和旅程（例如需要在给定时间到达）。因此，它可以很好地代表旅行的相对难易程度。详细描述了 IPTI 制定的基本原理，并讨论了该措施的优势和劣势。计算 IPTI 的实际可行性是通过描述一个产生令人鼓舞的结果的小型试点，并通过讨论大数据源和在线旅程规划工具的日益可用性提供的潜在效率来探索的。IPTI' 然后讨论其潜在应用：首先，它可以提供一种可理解的方式来展示人们面临的流动障碍的不同程度，这在试图解决不平等问题时可能很有用。其次，IPTI 可以通过显示给定计划对个人相对旅行能力的分布影响来为评估过程提供信息。论文最后提出了进一步研究的建议。