Grouping a set sequence of events

I'm monitoring traffic into a facility in real-time and events typically occur in a specific sequence [1-15-10-3] Please refer to insert below. My goal is to group (isolate the mentioned 4 events) so I can determine the total time each transaction took. i.e. referring to the first transaction from below, the vehicle was detected @ eventid1 ( (12:04:05am) and completed his transaction @ eventid3 (12:05:24) = 1min19seconds). There are instances where the sequence is only [1-10-3] and also as visible things can go wrong and you see a [1-1-15-10-3].

The challenge is that I have no field available that identifies a specific transaction and all I have is the expected sequencing of eventid's.  I need assistance grouping/isolation a set or completed transaction so I can do the math.