Headway Quality Measurement: Update

This article should be read in conjunction with Headway Quality Management: A Proposal for which this is a response to some questions and suggestions in the comments, and adjustments of my own in the interim. Specific routes discussed here are:

  • 52 and 952 Lawrence West local and express services
  • 504 King streetcar service (December 2020 before the diversions now in place for construction work)

Changes in format include:

  • Better spacing of the columns in the headway distribution charts for clarity,
  • Separation of the AM and PM peak periods for an express service that only operates for a few hours of each period, and
  • Changes in the layout and colour scheme of the headway distribution charts to emphasize the portion of service that lies within the target band of headways.

Both routes reviewed here show the problems of branching services and wide differences in scheduled service. A service may look “good” where all of it branches overlap, but be much less reliable on the unique segments. Vehicles may or may not be “on time”, but service riders experience does not accord with the TTC’s claims of high reliability. Indeed, there are cases where schedules contain built-in gaps that exist as part of blending services and managing transitions between service periods. They “work” for the schedule, but not for the rider.

One can argue that my proposed methodology should be adjusted with narrower or wider target bands. That’s easy to do, but the important issue here is to measure service as riders actually experience it, looking at various points on routes and all times of the day. The TTC’s scheme of looking only at terminals and averaging results over all time periods buries variations in service quality that riders know all too well.

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