Driving Driving Driving in Seattle is not much fun at all - we recommend you save your car for weekend trips to the mountains and take the bus while you're in the city.
Traffic is nightmarish and depressing.
520 are the main routes east-west. Many highways in the region have carpool lanes. There are also small carpool lanes near freeway entrances that skip the meter light. A carpool is usually 2 or more people, except on highway 520 were you need 3. Bitter commuters who are stuck in traffic get a cheap thrill off of reporting cheaters.