Did he ever return?
Irene Ros has a visualisation of ridership on the Boston subway (famous from the Kingston Trio song back before I was born)
You can see how the rush-hour varies across the subway lines, with the Silver Line (to the airport) having only an evening rush hour, the Green line having a moderate morning peak, the Red and Orange lines having about the same peak in the morning and evening, and the Blue line having more of a peak in the morning.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »