Working with Intervals

Q: A list of times of the form represents the periods when a particular system is not working. For two such lists, how can I determine the periods when both systems are not working?

A: Carl Woll (carlw@wolfram.com) answers: The function timelist simulates non-overlapping timing data of the form .

Here are two lists of timing data.

After converting each period into an Interval using Apply, IntervalIntersection returns those periods when both systems are not working.