An analysis of air mass effects on rail ridership in three US cities

This paper examines whether daily weather affects ridership in urban transportation systems. When examining human-weather relationships, it is often advantageous to examine air masses, which take into account the entire parcel of air over a region. Spatial synoptic classification characterizes air masses based upon numerous meteorological variables at a given location. Thus, rather than examining temperature or precipitation individually, here we compare daily ridership to synoptic air mass classifications for three urban rail systems: Chicago Transit Authority (CTA), Bay Area Rapid Transit (BART), and the Hudson-Bergen light-rail line in northern New Jersey. Air masses are found to have a significant impact on daily rail ridership, with usage typically increasing on dry, comfortable days and decreasing on moist, cool ones, particularly on weekends. Although the comfort of a particular air mass changes throughout the year, seasonality is not a significant factor with respect to the air mass-ridership relationship. The results of this study can benefit rail system managers who must predict daily ridership or in the development of cost-benefit analyses for station improvements. (C) 2008 Elsevier Ltd. All rights reserved.