The SR 99 southbound Duwamish River Bridge will have overnight closures beginning at 9 p.m. March 5, 6, 14 and 15. The bridge also will be reduced to two lanes 24 hours a day March 10-15. There are a number of alternatives drivers may choose if they wish to avoid delays, including the South Park Bridge, the East Marginal Way South Bridge, the Tukwila International Boulevard Bridge and I-5.