I am running late =
I am late
I am behind in my schedule
Examples:
John, I'm running late, can we change our 3PM meeting to 5:30PM?
Sorry Jane, I'll have to take a rain check on dinner, I'm running late.
The trains are running late today...there's no way I'll get to New York on time.
Source: http://forum.wordreference.com/showthread.php?t=340492