(Portland, OR) -- Four miles of I-5 will be closed in both directions starting at 9 p.m. Friday night in Southwest Portland. Crews are working to replace the 26th Avenue overpass. The project has been underway for nearly a year. The new overpass is being built under the current overpass. This weekend work is the only closure required during the entire project. I-5 will be closed southbound at Terwilliger Boulevard and northbound at Barbur Boulevard. Drivers will need to use I-205, I-84, Highway 217 or Highway 26 as alternate routes. I-5 will reopen by 5 a.m. on Monday.