This section describes the estimated time of departure (ETD) and estimated time of arrival (ETA) handling for shipments and segments.
Shipments and segments can have the following times:
- Actual start and stop times.
- Provided ETD/ETA times.
- Calculated ETD/ETA times.
The actual times are updated when the shipment or segment state changes, and they tell the time when the state transition actually happened.
Provided times are the planned times for the shipment. When you create a shipment you can give the
providedEta times for the shipment and segments in the shipment creation request.
If you create a shipment from a shipment plan that has
durationS values defined for its segment plans and a
shipmentDeparture time is given in the shipment creation request, the provided times for the shipment are initialized based on given
shipmentDeparture time and segment plan
After the provided times are set, the Tracking backend does not change their values.
Calculated times are the estimated times for the shipment. The estimates are calculated by the Tracking backend as the shipment progresses. The estimate recalculation is triggered when the segment statuses change and also when a tracker used in an ongoing shipment makes an ingestion.
Whenever a segment's calculated ETA estimate is updated, the subsequent segment's estimates are also updated and recalculated to reflect the change in the ETA of the preceding segment.
The calculated values can originate from multiple sources which are described below.
Initial values from shipment plan
If you create a shipment from a shipment plan, the initial calculated values are computed from the
shipmentDeparture time given in the shipment creation request and the
durationS values in the segment plans, if they are available.
If a shipment's segment is a road segment, that is it has either a
truck as its
transportMode, the segment ETA is calculated by estimating the duration it takes to traverse the segment. Depending on circumstances, the estimate might be based on past trace, planned or most likely route to the next waypoint, live traffic conditions, regional rest time regulations, learned driving patterns, and other factors.
The remaining segment duration for an ongoing segment is calculated from the latest position of the segment's tracker to the segment destination location, if the calculation is triggered by ingestion from the segment's tracker. For the subsequent pending segments, the estimates are updated by calculating durations from the segment origin to segment destination.
Previously completed segment durations
For other than road segments, the estimates for segment duration are obtained from previously completed segments which have used the same
transportMode, origin location and destination location as the segment to be estimated.