(Portland, OR) -- The bottom deck of the Marquam Bridge, I-5 southbound, will close late Friday and Saturday nights this weekend for an annual inspection. The closure will start at 10 p.m. and end at 6 a.m. I-5 southbound traffic will be detoured onto I-405 at the Fremont Bridge. I-5 southbound will close at the Rose Quarter will all traffic directed onto I-84 eastbound. The Marquam Bridge is 57 years old.