Fast track Question! please answer!?

-So I was going to Long Beach from San Diego. I accidentally took a toll road... I have never taken one of these before - but this time I had no choice. I read the signs "Fast track" (<-- or something of that nature) and another sign saying toll booth with a big sign under it saying CASH ONLY. I had no cash on me, so I decided to take the fast track route. I just got home, and wanted to know what Fast Track was, and how will they charge me? If I was wrong in taking this route, please inform me of a way to pay the toll... or pay the ticket before I even receive it(If I get a ticket for this...). Thanks in advance.