Schedule Mechanics & Data
Contemporaneous Critical Path
The contemporaneous critical path is whichever chain of activities was actually driving the project's finish date at a specific point in time -- as opposed to whatever the original baseline predicted it would be.
Definition
The critical path isn't fixed for the life of a project -- as activities finish, slip, or get resequenced, a different chain of activities can start driving the finish date than the one the baseline schedule originally identified. "Contemporaneous" critical path emphasizes using the real, as-of-that-moment driving path from each schedule update, rather than assuming the baseline's critical path stayed the same one throughout. Getting this wrong -- attributing delay to an activity that had already stopped being critical by the time it slipped -- is one of the more common analytical errors in a delay dispute.
Example
The baseline identified structural steel as critical, but by month four, a permitting delay had already made MEP coordination the actual driving path -- a later steel slip during that period didn't delay the project at all, since steel wasn't contemporaneously critical anymore.