You cruise down Fifth Avenue in downtown Seattle as the monorail rumbles above you. You're in the right-hand lane, on the Belltown side, but you realize you need to be at the far left if you're going to swing a turn toward I-5 in a few blocks. Changing lanes would mean swerving underneath the monorail columns. Pop quiz, hotshot: what do you do?

Most Seattleites go for it, changing lanes on Fifth Avenue as if there wasn't a nearly 94,000 pound train lurching its way from Westlake to Seattle Center about 30 feet overhead. But at some point, most of us probably wonder whether what we're doing is technically legal.

We asked the Seattle Department of Transportation, and at first got an email response that suggested we go-for-it folks were in the wrong. Deputy press secretary Chris Miller passed along that entry 3B.04.20 of the state MUTCD, or Manual on Uniform Traffic Control Devices, states “Where crossing the lane line markings is discouraged, the lane line markings shall consist of a normal or wide solid white line.” That sounds like the two solid white lines under the monorail. Somewhat, er, discouraging.

In need of clarity from a human, as opposed to a manual, we spoke to Matt Beaulieu, a manger in SDOT's transportation operations division. Fortunately he got right to the point: "Yes, you can change lanes under the monorail." Mid-block, that is; Beaulieu notes that "There's a whole rabbit hole about changing lanes in an intersection" and that he wasn't going to touch on that particular activity.

Why the big white lines and confusion then? Well, for one thing, SDOT wants people to take extra caution in the unique set-up; the sizable columns that run down the middle of the road are an unusual hazard. We don't set up slalom poles on our roadways all that often. "It is uncomfortable, and you have to be cautious and careful anytime," says Beaulieu. He says that SDOT's aim is to make operations intuitive, and encourage safe behavior.

So the short answer is that no, we're not all breaking the law every time we bop from a 5 Point Cafe brunch to Capitol Hill. When the monorail was installed in 1961, the skyline around Fifth Avenue was a lot lower—but it was still a busy street in a big city. For more than 60 years we've been weaving in and out of the area, and Beaulieu says he doesn't know of any increase in traffic incidents related to lane changes in the area. In other words, the current system has worked for a long time, even if a lot of us think we're getting away with something.