(Portland, OR)  --  The northbound span of the Interstate Bridge is set to close tomorrow night for its regular inspection.  I-5 northbound traffic should use I-84 and I-205 as a detour.  A team will inspect the bridge's steel structure.  The inspection is conducted every two years.  The bridge will be closed from 11 p.m. Saturday through 7 a.m. on Sunday.  The Jantzen Beach on-ramp to I-5 northbound will also be closed.  The northbound sidewalk will be closed, but the sidewalk on the southbound span will remain open.