I thought I’d follow up on Martin’s post on Amtrak’s long-distance reliability numbers with some Cascades data that is highly relevant to the conversation. Commenters expressed frustration with using mean performance as a single indicator of success, and many asked not only for Amtrak’s definition of ‘on-time’, but also to see median, mode, and ‘full-distribution’ data for Amtrak trains. The problems with ‘mean performance’ have already been kicking around the transit blogosphere lately, and I see little reason to simply reiterate something others have already said well. But I always find it useful to add data and visuals to a conversation.
By Amtrak’s on-time performance definitions, trains can be 10-30 minutes late (depending on route distance) and be considered ‘on-time’. With such a wide scope, the concepts of ‘on-time’ and ‘reliability’ begin to drift apart in meaning. Reliability should mean a consistent travel experience, both qualitatively (comfort and service) and quantitatively (speed and on-time performance).
Check out the chart above. Using data from the invaluable Amtrak Train Status Archives, I charted the performance of two morning train segments (#510 Seattle to Vancouver BC, and #513 Vancouver BC to Seattle only) for January 1-June 30 2010.
More after the jump…