Bethany and Cedar Mill residents who drive into Portland should plan for commute times two to three times longer starting Friday, Sept. 11.

All southbound Interstate 5 lanes through the Rose Quarter shut down at 10 p.m. that night for up to five weeks of round-the-clock construction. The closure spans a two-mile stretch between Interstate 405 and Interstate 84, affecting roughly 120,000 vehicles a day, the Oregon Department of Transportation (ODOT) said, according to the Portland Tribune.

Local southbound traffic will be detoured to I-405 southbound, the route westside commuters on Highway 26 would use to reach downtown. ODOT is directing long-distance travelers to Interstate 205 instead. Both I-405 and U.S. 30 across the St. Johns Bridge are expected to see heavy congestion, especially from 6:30 to 9 a.m. and 4 to 8:30 p.m., The Oregonian reported.

"Traffic will look different day to day, and checking navigation apps before you head out the door and giving yourself plenty of time to reach your destination is the best guidance we can provide," ODOT spokesperson Rose Gerber told The Oregonian.

ODOT has sent closure data directly to Google Maps, Apple Maps and Waze so the apps account for the shutdown when routing drivers. The Portland Bureau of Transportation has also coordinated with mapping platforms to reduce trips routed through neighborhood streets.

I-5 northbound remains open throughout the closure.

I-84 westbound to I-5 southbound also stays open, along with one lane to the Broadway/Weidler exit for local access.

Why the full shutdown

Crews are replacing the highway surface, last replaced in 1985, according to The Oregonian. The work is Phase 1A of the I-5 Rose Quarter Improvement Project and includes stormwater upgrades near I-5 and I-405, bridge repairs near I-5 and I-84, and extending a southbound auxiliary lane between the I-84 and Morrison Bridge exits.

ODOT estimated Phase 1A construction at $75 million. The full project carries a price tag between $1.96 billion and $2.08 billion.

The agency said a complete five-week shutdown saves up to $9 million compared to single-lane closures that would have stretched four months or weekend closures lasting two years. If work stays on schedule, southbound I-5 reopens by mid-October, The Oregonian reported.

Transit alternatives for westside riders

TriMet plans to run double cars on key MAX lines during the closure. The MAX Blue Line, which serves the Sunset Transit Center in Beaverton, connects westside riders to downtown Portland.

TriMet also recommends the MAX Yellow Line for commuters coming from the north, with trains running about every 15 minutes. Park-and-ride options include the Delta Park/Vanport and Expo Center lots.

Portland City Council voted to give free TriMet passes to roughly 9,000 city employees for the duration of the closure.

TriMet customer service is available at 503-238-7433 on weekdays from 7:30 a.m. to 5:30 p.m. Residents can also visit ODOT's TripCheck site or download the Get There Oregon app to plan routes and check real-time conditions.