I'm not sure how I managed to live here over 3 1/2 years without realizing this, but...
Note to Self:
You know the HOV-3 lanes on 395 South? You know how they have somewhat infrequent freeway off-ramps? Well, it turns out that those lanes going northbound have no off-ramps. At all. So if you think you're going to save yourself some time getting to Shirlington or something by jumping into the HOV lanes to scoot around some traffic, think again. Failure to remember this will result in a doubling of your transit time, as you will have to go all the way to the traffic circle by Memorial Bridge and turn around.
That is all.