 Near SeaTac Airport, the ramp from 99 to eastbound 518 is closed for the weekend. And heavy congestion throughout downtown Seattle. Mercer and Denny are busy around Seattle Center, and northbound I-5 is jammed up at the merge with I-90. And heading into downtown, construction on northbound I-5 has the road down to two lanes at Boeing Field. Drive time from Tacoma to Seattle, 94 minutes.