If you’re heading south through Portland anytime over the next several weeks, your usual route is about to look very different.

Beginning Friday night, September 11, the Oregon Department of Transportation will shut down southbound Interstate 5 through Portland’s Rose Quarter for up to five weeks. According to ODOT’s current closure information, the freeway is expected to be completely closed by about 10 p.m., although some ramps could begin shutting down around 9 p.m.

The closure will remain in place 24 hours a day, seven days a week while crews tackle long-overdue repairs to one of the busiest stretches of interstate in Oregon. While the construction zone itself covers only a relatively short piece of freeway, transportation officials expect the traffic effects to ripple across Portland, into surrounding neighborhoods and potentially all the way north into Washington.

Here’s Exactly Where I-5 Will Close

Southbound I-5 will close through the Rose Quarter between the I-405 interchange and the point where westbound I-84 merges with I-5. Northbound I-5 will remain open throughout the project.

There is one important exception for people headed into the Rose Quarter. ODOT’s project information says one southbound lane will remain open from the I-405 split to Exit 302A at Broadway and Weidler, preserving local access to the Moda Center and surrounding area.

Several familiar ramps will be unavailable. The southbound onramps from Alberta Street, Greeley Avenue, northbound I-405 at the Fremont Bridge, and Wheeler/Williams/Ramsay near the Moda Center are among those closing. The southbound I-5 connection to eastbound I-84 will also be unavailable, as will the southbound I-5 offramp toward the Morrison Bridge.

Meanwhile, the Rosa Parks Way and Going Street onramps remain usable north of the closure, the Broadway exit will remain open, and westbound I-84 traffic will still be able to merge onto southbound I-5 beyond the closed section. Drivers coming west on I-84 will also retain access to the Morrison Bridge.

Friday Night’s Closure Is Being Timed Around the Moda Center

The timing of the shutdown has an interesting Portland wrinkle. Weezer is playing the Moda Center Friday night, meaning thousands of people will be leaving the Rose Quarter at almost exactly the time ODOT needs to close the freeway.

ODOT officials told Oregon Public Broadcasting that the Wheeler Avenue southbound onramp by the Moda Center will be the final ramp to close. The goal is to give concertgoers a chance to clear the area before that access disappears.

That’s worth remembering for future events too. The Moda Center and businesses throughout the Rose Quarter aren’t closing simply because I-5 is. Concerts, games and other events will continue, but getting in and out could take considerably more planning than usual.

Some Trips Could Take Two or Three Times Longer

This is not expected to be a typical construction slowdown where everyone taps the brakes for a mile and moves on.

The Portland Bureau of Transportation’s Shift Your Trip guidance says ODOT is forecasting interstate travel times of two to three times longer than normal. Congestion could extend north across the Columbia River into Washington and spread onto Portland streets as drivers look for ways around the closure.

The busiest periods are also expected to grow longer. Officials currently anticipate heavy morning traffic from around 6:30 to 9 a.m., while the afternoon and evening rush could stretch from roughly 4 to 8:30 p.m.

Those delays make a little more sense when you consider just how heavily traveled this corridor is. OPB reported that about 120,000 vehicles use I-5 through Portland each day, including approximately 11,700 trucks carrying more than $100 million worth of goods.

The Traffic Won’t Stay on I-5

Anyone thinking they’ll simply duck off the interstate and zip through North Portland may find a few thousand other people had exactly the same idea.

Portland transportation officials expect heavier traffic on I-405 and Highway 30, including the route across the St. Johns Bridge. The city has also identified the Morrison and Steel bridges and streets including Greeley Avenue, Interstate Avenue, Mississippi Avenue, Vancouver Avenue, Broadway, Northeast 15th, Northeast 33rd and Martin Luther King Jr. Boulevard as likely congestion points.

PBOT has been preparing North and Northeast Portland for the spillover. According to the city’s District Two closure plan, crews have been filling potholes, refreshing pavement markings and cleaning bike routes ahead of the closure.

OPB also reported that transportation officials plan to use measures around schools and neighborhoods to discourage people from turning residential streets into unofficial freeway bypasses. That includes traffic barrels, temporary speed-reader boards and additional crossing flags as students settle back into the school year.

Passing Through Portland? Look at I-205 First

For travelers simply trying to get through the Portland metro area rather than stop downtown, I-205 may be the most practical alternative.

ODOT is directing long-distance through traffic toward I-205, while vehicles already entering central Portland will largely be diverted onto southbound I-405. Neither route is guaranteed to be painless. Both are expected to absorb significant additional traffic once I-5 closes.

That makes real-time navigation particularly important during the next several weeks. A detour that saves time one morning could become the slowest option the next afternoon, especially if there’s a crash, stalled vehicle or major event somewhere along the alternate route.

If you’re making a longer Oregon road trip through Portland, checking conditions before reaching the metro area could give you considerably more flexibility than waiting until brake lights are already filling the windshield.

MAX Could Be One of the Best Ways Around the Gridlock

For Portland-area commuters who can leave the car behind, rail may offer one of the least stressful options.

TriMet is specifically recommending MAX trains during the I-5 closure because trains operate largely outside ordinary vehicle traffic. Buses will continue running, but routes using congested Portland streets may face many of the same delays as cars.

The Yellow Line could be particularly useful for people traveling between North Portland, the Vancouver area and downtown. A typical MAX trip from the Expo Center to downtown Portland takes about 30 minutes, and trains normally arrive every 15 minutes or better through much of the day.

There are also several Park & Ride options. Metro has temporarily designated 200 spaces at the Expo Center for TriMet riders during the closure, while Delta Park/Vanport has 304 parking spaces.

There’s even a new option for commuters coming from Washington. During the closure, a temporary C-TRAN Route 500 will run between Vancouver’s 99th Street Transit Center and the Delta Park/Vanport MAX station, where passengers can transfer to the Yellow Line.

On Portland’s east side, TriMet suggests looking at the Red and Blue MAX lines as alternatives to driving portions of I-205 and I-84. Travelers coming from the south can also consider the Orange Line and Park & Ride facilities at Southeast Park Avenue and Southeast Tacoma/Johnson Creek.

Portland Is Asking People to “Shift Your Trip”

The city is taking the unusual step of asking people who have flexibility in their schedules to change not just how they travel, but when.

Portland’s Shift Your Trip program encourages people to use transit, bike, carpool, telework or adjust their commute to avoid the busiest hours. The idea is pretty straightforward. Every vehicle that doesn’t enter the most congested areas leaves a little more room for freight trucks, emergency vehicles and people who have no realistic alternative to driving.

PBOT is also organizing a special North and Northeast Portland City Bike Bus during the shutdown. Those rides will take place on Wednesdays from September 16 through October 14, giving people who may not normally bike downtown a group option for trying the commute.

The city is even encouraging Portlanders to use the disruption as an excuse to hang around a neighborhood business district until traffic eases rather than jumping directly into the evening rush. Honestly, there are worse excuses for grabbing dinner before heading home.

Why Close I-5 Completely for Five Weeks?

Five weeks of around-the-clock closure sounds drastic, but the pavement underneath Portland traffic has been waiting a long time for serious attention.

According to ODOT’s closure overview, the roadway surface has already outlived its expected 25-year lifespan. Years of heavy traffic have left the freeway with ruts, cracking, potholes and deteriorated areas that need more than another round of patches.

Crews will repair and reinforce weak sections, replace bridge joints, resurface the concrete deck and repaint highway lane markings. OPB has also reported that crews will add structural beams as part of seismic upgrades, improve signage and make drainage improvements designed to keep trash from entering the Willamette River.

ODOT considered less disruptive ways to do the work, but they came with a very different timeline. According to OPB, leaving one lane open could have stretched construction to around four months, while restricting major work to weekends could have dragged the project across two summers.

The agency estimates that completing the work during the concentrated five-week closure will also save roughly $9 million compared with the alternatives.

In other words, Portland gets one enormous traffic headache instead of a smaller one that sticks around for months.

Rain Could Still Complicate the Timeline

ODOT says southbound I-5 will be closed for up to five weeks, rather than promising an exact reopening date.

And this being Oregon in September and October, there’s one obvious wild card.

Rain can interfere with concrete work, paving and pavement striping, all of which are part of the project. OPB reported that transportation officials have acknowledged weather or unexpected construction problems could extend the schedule.

If everything goes according to plan, southbound I-5 should reopen around the middle of October. ODOT says it will reopen the freeway as soon as the necessary work is completed.

Emergency Crews Are Preparing for the Backup Too

The closure presents another problem that’s easy to overlook until you picture an ambulance trying to move through bumper-to-bumper Portland traffic.

Emergency agencies and transportation officials have been preparing for the possibility of increased congestion interfering with response times. Portland is asking drivers to be especially vigilant about moving to the right when emergency vehicles approach with lights and sirens.

PBOT is also planning to stage two tow truck operators near areas expected to experience the heaviest congestion. Beginning Monday, September 14, those operators can help move stalled or disabled vehicles out of traffic and into the nearest legal parking space.

The goal is to keep one breakdown from turning an already bad commute into something considerably worse.

Businesses Are Still Open During the Closure

The Rose Quarter and nearby North and Northeast Portland neighborhoods aren’t shutting down with the freeway.

In fact, local businesses may be among those hit hardest by the traffic changes if customers simply decide the area is too difficult to reach. ODOT has created a special resource page for businesses affected by the closure and is emphasizing that restaurants, shops and other businesses remain open.

If you already have dinner plans, tickets to an event or another reason to head into the area, there’s no need to automatically cancel. Just allow considerably more time and check the route before leaving.

Supporting those businesses might be particularly worthwhile over the next month. Five weeks is a long time when thousands of potential customers are being warned that traffic near your front door could be some of the worst Portland has seen in years.

For the Next Five Weeks, Check Before You Leave

There probably won’t be one secret Portland detour that solves this for everyone.

If you’re traveling through Portland without needing to stop downtown, check I-205 before automatically continuing toward the Rose Quarter. If you commute locally, consider whether MAX, carpooling, shifting your hours or working remotely makes sense. And if you’re heading to the Moda Center, Convention Center or somewhere nearby, remember that the neighborhood remains accessible even though some of the usual freeway entrances and exits won’t be.

Most importantly, give yourself more time than you normally would and look at current traffic conditions before leaving.

For the next five weeks, “I know how long it takes to get through Portland” may be a fairly dangerous assumption.