Sorry about your commute, man, that is absolutely crappy. Hope your day gets better, if I was in Arlington today I'd have to buy you a beer.

That switchback is, indeed, absolutely awful. Since it's obviously a deathtrap, I've always taken it at 10mph or less. And even that slow, I wiped out when my front wheel (25mm) hit something I couldn't see, right when I was at the apex of the upper turn. Combine tight turn+steep downhill+tree debris+shadows and it's pretty much guaranteed disaster for roadie tires.

Based on our collective experiences crashing there, I wouldn't ride it again with less than 28mm tires at any speed, maybe even 32mm.

I'm with JPCowan, I think I'll be dismounting there from now on. It might be a good idea if there was a sign to that effect - "folks with skinny tires need to dismount". Also JPCowan - please do report back if you find a good detour to that S-curve.

BDCheung, welcome to the "I wrecked the Custis switchback" club. We should get jerseys printed.