How Should a Tool Describe an Unscheduled Transfer?
From the earlier reference collection. Read the current software blog.
A transfer description should distinguish an explicit guarantee or timed connection from a merely possible itinerary assembled from schedule times.
Do not imply a promise
Two trips that appear to connect in a journey planner do not necessarily form a guaranteed connection. A planner may simply find that the first scheduled arrival precedes the second scheduled departure by enough time for its configured walking or transfer allowance. Unless the data or agency guidance establishes a connection guarantee, describe it as a possible itinerary.
GTFS includes transfer-related data structures, but a tool still needs to explain what its particular source data says and what its routing logic infers. The format’s reference is a useful guide to the available dataset fields. [GTFS schedule reference](https://gtfs.org/documentation/schedule/reference/)
Separate three cases
A guaranteed connection is one the responsible service provider explicitly commits to hold or protect under stated conditions. A timed transfer indicates a planned coordination, but the exact rider-facing implication should be based on the agency’s definition. A possible connection is a calculated itinerary with no special promise attached.
For example, if a bus is scheduled to arrive at 10:02 and a train departs at 10:08, a planner might label the option “6-minute transfer” when the walk is feasible. It should not call that “guaranteed” merely because the times fit. If source data marks a special relationship, the product can explain that status using terminology supported by the publisher.
Show the assumptions
A useful transfer card identifies the arrival stop, departure stop, scheduled times, and estimated transfer interval. If the stops differ, show the walking link or distance when available and identify whether it is an estimate. If accessibility or platform details are unknown, do not imply that the interval works for every rider.
When a transfer is not explicitly designated, a short phrase such as “possible connection based on scheduled times” communicates the planner’s reasoning. If a source marks a timed or protected connection, say so plainly and provide relevant conditions when known.
Make uncertainty actionable
A rider needs to know what could make the connection fail: a short interval, a walk between stops, a schedule change, or the absence of a hold commitment. Present these details close to the itinerary rather than burying them in general help text. Where real-time data is available, keep its estimate distinct from the scheduled times and show when it was updated.
Precise labels help riders choose among routes and help agencies avoid unintended promises. A tool should describe what the schedule supports, identify any special connection status, and leave unsupported guarantees out of its wording.