Service alerts allow you to provide updates whenever there is disruption on the network. Delays and cancellations of individual trips should usually be communicated using Trip updates.
You have the option to provide the following:
URL - link to your site explaining more about the alert
Header text - a summary of the alert
Description - a full description of the alert, which will always be shown alongside the header (so should not repeat this information).
The alert will be displayed where appropriate within the given time range. This range should cover the entire time that the alert is useful for the passenger to see.
If no time is given, we will display the alert for as long as it is in the feed. If multiple ranges are given, we will display during all of them.
Entity selector allows you specify exactly which parts of the network this alert affects, so that we can display only the most appropriate alerts to the user. You may include multiple entity selectors for alerts which affect multiple entities.
Entities are selected using their GTFS identifiers, and you can select any of the following:
Agency - affects the whole network
Route - affects the whole route
Route type - affects any route of this type. e.g. all subways.
Trip - affects a particular trip
Stop - affects a particular stop
You may include more than one of the fields listed above in one informed_entity. When multiple fields are included in one informed_entity, they should be interpreted as being joined by the AND logical operator. In other words, the alert should only be applied in a context that meets all of the fields provided in an informed_entity. For example, if route_id: "1" and stop_id: "5" are both included in one informed_entity, then the alert should apply only to route 1 at stop 5. It should NOT be applied to any other stop on route 1, and it should NOT be applied to any other route at stop 5.
If you would like to represent an alert that affects more than one entity (e.g. an alert for both route 1 and stop 5) , you should add multiple informed_entity to your alert, with each of them applying to the affected entity (e.g. one informed_entity that includes route 1 and another informed_entity that includes stop 5).
What is the cause of this alert? You may specify one of the following:
Other cause (not represented by any of these options)
What effect does this problem have on the specified entity? You may specify one of the following:
Significant delays (insignificant delays should only be provided through Trip updates).
Modified service: Operations are different from what the rider would normally expect. An example is an alert that reminds riders of an upcoming holiday schedule that is different from normal service on that day of the week.
Other effect (not represented by any of these options)
No effect: The alert provides information to riders but does not affect operations. Examples include advertising public meetings and soliciting feedback via surveys.
Accessibility issue: The alert provides information about accessibility issues that affects step-free access. Examples include an out of service elevator or movable ramps.