Transit systems play a key role in improving access to job opportunities and basic services such as health and education. Most studies in the literature calculate transit accessibility using traditional place-based indicators that measure accessibility at a given location. However, because transit routes are the main unit of analysis in most approaches for planning and operation of transit systems, these accessibility indicators provide limited information to inform transport planning at the route-level. In addition, previous studies have demonstrated the methodological limitations of traditional place-based accessibility metrics to study the association between accessibility and transit ridership. In this paper, we propose a novel route-based accessibility measure to fill the mentioned gaps. The indicator measures the average level of access to opportunities provided by a given transit route to the population in its extended catchment area. This indicator is flexible enough that it can be calculated using different travel cost functions and can be applied to measure access to different activity types for the whole population or for specific groups. To illustrate the applicability of the proposed indicator, we calculated the employment accessibility provided by all routes of the transit system of Fortaleza, Brazil. We also show that the proposed indicator has greater predictive power of transit ridership than other route-level accessibility measures found in the literature. This paper provides a methodological contribution that could help transport planners incorporate accessibility analysis into transit system redesign projects, and help practitioners anticipate what accessibility impacts and subsequent changes in transit ridership could be expected from route-level service changes, and to examine the influence of accessibility on transit ridership.

交通系统在改善就业机会和卫生和教育等基本服务方面发挥着关键作用。文献中的大多数研究都使用传统的基于地点的指标来计算交通可达性，这些指标衡量给定位置的可达性。然而，由于公交路线是大多数公交系统规划和运营方法中的主要分析单位，因此这些可达性指标为路线层面的交通规划提供的信息有限。此外，之前的研究已经证明了传统的基于地点的可达性指标在研究可达性和公交客流量之间的关联方面存在方法上的局限性。在本文中，我们提出了一种新颖的基于路线的可达性措施来填补上述空白。该指标衡量特定过境路线为其扩展服务区域内的人口提供的机会的平均水平。该指标足够灵活，可以使用不同的旅行成本函数进行计算，并可用于衡量全体人口或特定群体对不同活动类型的访问情况。为了说明拟议指标的适用性，我们计算了巴西福塔雷萨交通系统所有路线提供的就业可达性。我们还表明，与文献中发现的其他路线级别的可达性指标相比，所提出的指标对公交客流量的预测能力更强。本文提供了一种方法论贡献，可以帮助交通规划者将可达性分析纳入公交系统重新设计项目中，并帮助从业者预测路线级服务变化可能带来的可达性影响和公交客流量的后续变化，并检查可达性的影响关于过境乘客量。