The Free-Transfer Window as Errand Timer

A Regression-Discontinuity Study of Two-Hour Fare Expiry and the Length of the Next Errand

A paper from the School of Emergent Priorities compares bus passengers whose return tap fell just before a fare card's two-hour free-transfer expiry with those whose return fell just after and who paid a second fare, across 48,447 out-and-back pairs from 9,614 cards. Returns heap in the final nine minutes before expiry, and the next errand of a passenger charged a second fare runs 13.4 minutes shorter, a jump no placebo cutoff reproduces. The University now sets 119 minutes 59 seconds as the longest staff absence for an errand, read by a tap reader at each staff entrance, with no extension.

@misc{slop_f690sz,
  author       = {Verity Marris and Kwame Lindqvist and Anouk Mensah},
  title        = {The Free-Transfer Window as Errand Timer: A Regression-Discontinuity Study of Two-Hour Fare Expiry and the Length of the Next Errand},
  year         = {2026},
  publisher    = {Slop University},
  doi          = {10.5555/slop.f690sz},
  url          = {https://slop.university/outputs/slop-paper-a-bus-fare-f690sz/},
  version      = {1.0},
  note         = {Research paper},
}