"Scalpel, ...Retractor, ... Jack Hammer."

We too do forensic science.
Fortunately without the blood and gore.
Here we are starting a postmortem on a stretch of highway that is giving us a lot of grief.

A series of test pits will be dug down through the road. The material excavated will be bagged and analysed for moisture content, material composition and strength.
Tests will be done to see what the best remedial tactic will be, maybe the addition of a lime stabilizer for instance.

A keen eye also helps.
We noticed tiny pin holes in the seal. A truck tire would force water through these, washing out the fines in the road metal and leaving a small cavity.
The seal would then fail as it cracked, under load.
You can see the grey staining from the road metal below my fellow worker's boot.

My money is on "Seal Failure".