I have been also wondering why as well. The trench starts where the existing wall ends and looks like the concrete wall will continue as a curve and then at a right angle but I can’t believe it will be that long as it is half way to the drop off zone and if you are the wrong side of it it’s a long walk to get around it.
Another airport mystery is what is happening to the 5 drop off lanes that are under construction. Each lane appears to be a cold de sac with no exit route. Yes once a car enters it has to turn around and cross the path of cars entering the next cold de sac.
Looks like a pending disaster to me unless I am missing something.