Review of Persistent Metro Card Balance Guess Activity

ANNUAL REVIEW: METRO CARD BALANCE GUESS

Review Period: Full Year Behavior: Approaching the metro gate without confirmed card balance Protocol Status: Unofficial but well-established

Q1 Summary

The card was topped up in January. Balance: sufficient. The metro was taken sixteen times before the balance was next checked.

The balance was checked not proactively but reactively, at the gate, when the gate communicated the balance via audible feedback and the movement of the bar.

The governing rule: any metro card balance guess that works twice in city life becomes an unofficial protocol until conditions change.

Q2 Summary

April incident: the gate beeped. The bar did not move. The queue behind the gate did not disperse.

The metro card balance guess has a failure mode and the failure mode is public: the gate beeps, the bar does not move, and the queue behind you provides an informal audience.

Time to resolution: forty-five seconds. Card reloaded at the machine adjacent to the entry. Second attempt: successful. The queue had moved but was aware of events.

Q3 Summary

Post-April: balance was checked before entry on fourteen consecutive trips. This represents the largest streak of pre-verification in the annual record.

By September, pre-verification had lapsed back to approach-and-see.

Q4 Summary

The gate knows. The gate has always known. The person approaching it did not.

Annual Finding

| Metric | Count | |--------|-------| | Trips taken this year | ~120 | | Trips with pre-verified balance | 18 | | Gate-confirmed balance checks | ~102 | | Gate failures (insufficient balance) | 3 | | Public incidents | 3 |

Soon the city behaves as though the improvised protocol was planned from the beginning.

The gate is reliable. The balance check is outsourced to it. This is not an endorsed method. It is, however, the practiced one.

Q1 recommendation: Top up before leaving the house. Adoption: unlikely.