Alerts

Alert

General guidelines for alerts:

• When trip_id and start_time are within exact_time=1 interval, start_time should be later than the beginning of the interval by an exact multiple of headway_secs.
• When canceling trips over a number of days, producers should provide TripUpdates referencing the given trip_ids and start_dates as CANCELED as well as an Alert with NO_SERVICE referencing the same trip_ids and TimeRange that can be shown to riders explaining the cancellation (e.g., detour).
• If an alert affects all stops on a line, use a line-based alert instead of a stop-based alert. Do not apply the alert to every stop of the line.
• While there is no character limit for service alerts, transit riders will often be viewing alerts on mobile devices. Please be concise.

Field Name	Recommendation
description_text	Use line breaks to make your service alert easier to read.