Reference NP's second post and link to Google Earth. The Red - Orange marker was the South end of the NP Bridge, the track on the North side wyed, with the South leg curving past Emerald Galvanizing and Glass Eye Studios; this track was the originally the Seattle, Lakeshore & Eastern ( later NP ) line to Redmond, Issaquah, and North Bend. This is now part of The Burke - Gilman Trail ( the grass strip too).
The North leg of the wye went past Bodycenter Studios and Northwest along the North side of Salmon Bay, then North and NE past the current Ballard Locks, aka: Hiram Chittenden Park & Locks - Army Corps of Engineers, to the current mainline North of BNSF's Bridge 4, the often - incorrectly called Salmon Bay Drawbridge. The Ballard Locks RR bridge is a more correct term. The NP bridge that is this thread's subject did cross Salmon Bay. I recall this bridge was also Great Northern's original route into Seattle from the North side of Salmon Bay. The trackage between the East side of NP Salmon Bay bridge and the connection with the GN just North of Bridge 4 was for many years joint GN / NP trackage. The Ballard Terminal RR. currently uses several miles of this line.