Editor’s note: Another version here.

Via Sightline pal Joe Cortright and Google maps, a graphic depiction of what happens when you toll a formerly free stretch of highway: drivers flock to a nearby, untolled route.

(The image is a web animation—so if it’s not flipping back and forth between two different maps, you may have to change your internet browser settings to allow “animated gifs.” Also, the “Toll” image is from this morning at 8 a.m., and the “No Toll” image is a typical weekday morning at 8 a.m.)

For those not familiar with Seattle traffic, SR-520 is the northern Lake Washington crossing on the map above. The bridge has been the bane of commuters for quite some time: state traffic figures suggest that it’s been full during rush hour for over a decade. But last week the state Department of Transportation put a $3.50 rush-hour toll on State Route 520—and drivers have flocked in droves to I-90, about 3.5 miles to the south. I-90 used to be the fast way across the lake, but now you’ll have to pay $3.50 for a quick rush-hour trip between Seattle and the east side.

Of course, the tolling is brand new, and it will probably take a few months for traffic patterns to settle into a new equilbrium. But for now, it’s clear that tolling is creating significant diversion to nearby toll-free routes—which is much what we argued would happen in our report on toll avoidance last year. The real question, though, is what will happen over the long haul. If tolling and congestion cut back on demand for car travel across Lake Washington, will the state be able to raise as much money as it needs to replace and repair the cross-lake bridges? At this point, we’ll just have to wait and see.