A few months back, the transportation consulting firm NelsonNygaard released a fascinating report that looked at what might happen to downtown Seattle traffic patterns if the state builds a tunnel through downtown, while imposing a steep toll on drivers who choose to take it. (We've already written about that report once before.)
Below, for your viewing pleasure, is the most important image from that report. Click it to see a larger version -- and I'll explain what it means in a moment.
There's a lot of information in the chart, but you can ignore much of it. The only thing I want you to pay attention to are the orange and yellow bars: