What is the Delta T*?
Delta T is another word for delay, a column in the Control Tower, present in both the trips view and the shipments view. It shows a number that is positive, 0 or negative. This can be in minutes or in hours, depending on your settings (the example on the left shows hours, the example on the right shows minutes):
The meaning of this number is: the largest present (predicted) deviation from the planned arrival time for this trip. So it is not an addition or average, but only the highest deviation visible.
Note: Completed, canceled or currently active stops are not included in this! So if a vehicle is currently at a stop, the current delay is not shown as DeltaT, but an expectation for later in the trip.
For completed trips, the DeltaT shows the largest difference from scheduled time that has occurred in the trip.
The colors of the numbers have to do with whether the stop is going to be "early," "on time," or "late". There is a general setting when an expected arrival time is considered 'too late' or 'too early'. These values can also be adjusted for each stop.
Note: Delta T shows to greatest delay. That is, the mathematically largest number of all deviations per stop. For trips that are Too Early, this means it can be the smallest deviation. For example: if a trip has two stops, where one will be delivered 20 minutes early (-0:20), and one 3 minutes early (-0:03) then the Delta T becomes '-0:03', because -3 is greater than -20.
These are the possible colors and their meanings:
- Blue and without underline: Default - Stop is on time
- Blue with red underline: not 'late', but AFTER the block time
- Red with red underline: 'late', exception
- Blue with orange underline: not 'too early', but before block time
- Orange with orange underline: 'too early', Exception
- No data received for a certain duration (the minimum duration at which this icon is shown is a setting). This icon also has a 'hover' function, it shows the time that data was last received and what the DeltaT was at that time:
* Note: this column may have a custom name in your Control Tower
Analysis of problems with Delta T
Delta T is missing or is +0
When a value for DeltaT is missing or has +0 as a value it may have one of the following causes:
- If the trip is not yet active and started, the DeltaT will always be 0.
- A stop will have a DeltaT of 0 if the vehicle is not late getting there and there is a 'wait time' set for the stop, from the planning. This means that the vehicle at this stop may only start loading/unloading from the scheduled time. Thus, it cannot then arrive 'too early'.
- There has been no GPS connection for some time, if all goes well a gray symbol will be shown indicating this. In the Vehicle tab at the bottom of trip details you can see when the last GPS data was recorded.
If it is missing or incorrectly zero for all or a large proportion of trips, this indicates a malfunction. If so, please contact Simacan Support.
Delta T is much higher or lower than I would expect
- Has the ride just been changed? Have stops been cancelled, moved or added? That could either make the scheduled time no longer realistic, causing DeltaT to get very high (or low). Or it could be that the new route is not planned correctly but still goes through a deleted stop, for example, or in the wrong order. This is especially true if changes are made on a ride that is already in progress.
- Possibly there is confusion about whether hours or minutes are shown in this field (this is adjustable). Ask a colleague about this; if it remains unclear you can ask Simacan Support. If the current setting is undesirable, contact your key user to request a change.
- Could it be that a stop has been logged off manually? This can also give a distorted picture of the stop times.
- Something has gone wrong, causing one (or more) stops to be logged off wrongly too early or in the wrong order. See also: determining the arrival time. If you cannot properly explain what happened, forward the trip to us for analysis.