I was on Spring Hill Road, getting ready to hop onto the Dulles Toll Road:
View Larger Map (screenshot b/c Blogger didn't like the iframe)
Now, it's covered by the Dulles Toll Road overpass, so you'll have to trust me on this, but there are two left turn lanes, which undergo a leftward lane shift as you pass under the overpass.
So, if you're in the left lane and not paying attention, you'll ignore the lane shift and continue straight, cutting off the driver next to you. If you're lucky, said driver will anticipate this, avoid the collison and simply honk his horn instead of getting all road-ragey.
However, if you decided to honk back at me (I mean, the other driver)... well, then, all bets are off and there's no telling what could happen.
I was seriously contemplating ways to initiate a frank and thorough educational discussion with the other driver, possibly leading to an ad-hoc brainstorming session, culminating in some concrete suggestions on improving the intersection that we could take to VDOT, but what ended up happening is that I stewed for a while, then went to Lake Anne, where I browsed for a bit at the Reston Used Book Shop (cut short because looking up at the higher shelves was hurting my neck), then went to Cafe Montmartre for a few drinks and to use the open wifi hotspot.
Incidentally, it's an optimal day for outdoor laptop use: No wind, no bugs, temperate, and cloudy enough so that the sun is behind a big diffuser, with minimal screen glare.