And then returns to two lanes, rinse, repeat. Not sure how you think widening Tacoma would happen. You'd need to tear down most houses and businesses that line the street. I live in Sellwood, trust me, the bridge is not the bottleneck.
I've driven over it many times, it's clearly a bottle neck. And read my post again, the worst part is they spent hundreds of million on a bridge that will become THE bottleneck if they ever try to improve traffic flow in Sellwood itself.