Fix: a bus appears to travel impossibly fast between two stops

Published: 3 July 2026. Last reviewed: 3 July 2026.

Code: fast_travel_between_consecutive_stops (MobilityData validator)

What this means

For some trips, the time between two consecutive stops in stop_times.txt is too short for the distance between them: the implied speed is faster than a bus could go. Either a stop time is wrong or a stop is in the wrong place.

Why it matters

Wrong times or locations make trip planners give riders bad arrival predictions and draw routes that jump around the map. A single fat-fingered time can make a whole trip look unreliable. The usual causes are a typo in a stop time, a stop placed at the wrong coordinates, or two stops that are actually the same place.

How to fix it

Check the trips the validator flags:

• A wrong stop time: correct the arrival_time / departure_time so the segment takes a realistic amount of time.
• A misplaced stop: fix the stop_lat / stop_lon in stops.txt so the distance is right. A stop dropped at 0,0 or at the wrong corner is a common cause.
• Duplicate stops: if two consecutive stops are the same physical location, merge them or remove the duplicate.

How long it usually takes

A targeted fix on the flagged trips. The count tells you how widespread it is; a single bad stop can explain many flagged segments at once.

Authoritative rule

fast_travel_between_consecutive_stops is a canonical MobilityData GTFS Validator notice used in validator reports across the GTFS ecosystem. Read the authoritative rule for fast_travel_between_consecutive_stops in the GTFS Validator rules. (opens on an external site)