Public transit offers older adults an important alternative travel mode for accessing social activity destinations. Given the growing size and socioeconomic diversity of the older population, transportation planners should consider how current urban transit systems can better meet their needs. In this study, we examine the time-varying accessibility to senior centers by public transit in each census tract of Philadelphia, Pennsylvania. Senior centers are community service and activity hubs for older adults which are typically overseen by the local area agency on aging. They offer a variety of services and social activities for older adults, including free meals, volunteering opportunities, information, and technology training. Using General Transit Feed Specification (GTFS) data and socioeconomic data from the U.S. Census Bureau, we analyze how accessibility varies across census tracts with respect to the tract's share of older adults, particularly those in vulnerable subgroups. We found that accessibility to senior centers declines from the downtown area to the suburbs but varies considerably among the vulnerable subgroups studied. We also found that when accounting for the open hours of senior centers, accessibility to senior centers is generally lower around midday (2 PM) than during peak hours (8:30 AM) on Mondays. We used the vertical equity index to examine social disparities in accessibility among older adults. We found that while SEPTA underserves neighborhoods with higher shares of older adults, tracts with higher shares of some vulnerable subgroups are better served than those with lower shares. Specifically, neighborhoods with higher shares of households that have no cars are better served than those with higher shares of African American and Hispanic older adults. These results suggest that the Southeastern Pennsylvania Transportation Authority (SEPTA) and the Philadelphia Corporation for Aging (PCA) should work together to better accommodate the diverse travel needs of older adults.

公共交通为老年人提供了一种重要的替代出行方式，以进入社交活动目的地。鉴于老年人口的规模和社会经济多样性不断增加，交通规划者应考虑当前的城市交通系统如何更好地满足他们的需求。在这项研究中，我们检查了宾夕法尼亚州费城每个人口普查区的公共交通对老年人中心的时变可达性。老年中心是老年人的社区服务和活动中心，通常由当地老年机构监督。他们为老年人提供各种服务和社交活动，包括免费膳食、志愿服务机会、信息和技术培训。使用来自美国人口普查局的通用运输供给规范 (GTFS) 数据和社会经济数据，我们分析了人口普查区域的可及性在老年人中所占的比例如何变化，尤其是弱势群体中的老年人。我们发现，从市中心到郊区，老年人中心的可达性下降，但在所研究的弱势群体之间差异很大。我们还发现，考虑到老年中心的开放时间，老年中心在中午（下午 2 点）左右的可达性通常低于周一的高峰时间（上午 8:30）。我们使用垂直公平指数来检查老年人在可达性方面的社会差异。我们发现，虽然 SEPTA 对老年人比例较高的社区的服务不足，但某些弱势群体所占比例较高的地区比那些比例较低的地区得到了更好的服务。具体来说，没有汽车的家庭比例较高的社区比非裔美国人和西班牙裔老年人比例较高的社区得到更好的服务。这些结果表明，宾夕法尼亚州东南部交通管理局 (SEPTA) 和费城老龄化公司 (PCA) 应该共同努力，更好地满足老年人多样化的旅行需求。