Macro or code to calculate the length of time a vehicle spends in a an area

Please can somebody help me, I know that this task can be completed manually, but thought that a macro or code would allow it to be automated.

I am trying to calculate the length of time a vehicle(s) spends in a an area and enclosed spreadsheet is an example of the data that is exported from the system.

I have a piece of code that works if the vehicle does not leave the area, but in reality it can leave an return many times over the course of the time period that the data is captured.

The data has,

1. the time in column A, the time is generated every time a vehicle enters or leaves the area, so a line of data can be created 2 or 5 minutes or any time after the previous line.

2. the columns B to ….. contains a vehicle identification. There may be any number of vehicles is the row as the number will increase or decrease as a vehicle enters or leaves the area.

Thank you in advance for your help.