You can manually get the average duration per trip by generating a “closed jobs” report here: https://admin.taxicaller.net/admin/reports/reports.php
Check “legacy report” and then filter it with the chosen period (either this week, last week or a preferred range). Click “get.” This report will show the duration for each job done. Duration means the time the driver has started the job until he has closed it.
When you have this report, download it to CSV format where you can modify and do the manual calculations. You would need to total all of the durations indicated and then divide it by the number of jobs performed. You will then be able to get the average duration on that period.