The Ten Minute Rush Hour

I have to admit, traffic patterns have always confused me a little bit.  There are times when there is congestion on a highway long past the actual obstruction (e.g., an accident) being removed.  It's almost like there's residual traffic, as a warning to everyone that "a bad thing happened here."  There are also times when there are a surprising number of cars on the road; for example, did you know that the east-bound lanes on both the Bay Bridge and the Caldecott tunnel consistently see a lot of traffic around noon on Saturdays?  Where are all of these people going?  You figure they can't ALL be going to lunch, and if they were going on a weekend trip, they would've left earlier in the morning.

So, with that as a caveat, perhaps you could excuse my confusion when there was a surprising amount of traffic going West on the Bay Bridge (i.e., into the city) a little after 7PM on a weeknight.  Generally, if I've left the office that late, I don't see much traffic anywhere.  After all, the vast majority of commuters are already home by that point.  Still, there were enough cars around that we all had to account for each other and drive at a sane speed.  So, I raised an eyebrow when I encountered this.  Like I said, though, traffic patterns confuse me, so I just shrugged it off.

However, the next time I was crossing the Bay Bridge at roughly that time, I figured out why this particular pattern existed.  This time, I was probably about 5 to 10 minutes earlier, so I was pulling up to the toll plaza pretty much right at 7PM.  To my surprise, I noticed that there were a non-trivial number of cars that had pulled over onto the various shoulders of the roads leading up to the toll plaza.  And right around 7PM, when I was pulling up to the toll plaza, several of them started to pull out into traffic.

You see, the Bay Bridge has a toll system that's based on what time you cross the bridge.  Want to guess when the price drops from the "peak" rate to the "off hours" rate?  Yup, 7PM on a weeknight.  I can't be absolutely certain that they were trying to wait out the increased fee, but I saw something like 6 cars all do this in the brief time it took me to pull up to the toll booths.  Somehow, I doubt they all got flat tires or had to make emergency phone calls all at the same time.

Also, I don't remember there being any significant traffic on the days when I've been on that road 30 minutes later.  If I didn't know any better, I'd say there was a brief spike in traffic for roughly 10 minutes, pretty much right after 7PM.

Sure, this very well could be a bunch of coincidences or there could be a different, but still legitimate, explanation.  If I choose to believe that, however, I'm back to just being confused about how the world works.  Frankly, that's no fun, so I choose to believe my explanation.  Also, making up amusing explanations for every day occurrences is kind of fun (and a minor hobby of mine), so that's a second reason for sticking with my story.

With that, the mystery of the ten minute rush hour is solved: there are apparently a bunch of  people out there who will gladly trade ten to fifteen minutes for two dollars.