SEATTLE –  For weeks, we have been warned about the 19 day construction project on northbound I-5 that begins on Friday, but it's not only I-5 that will be affected.

On weekends, many of the on-and off-ramps around downtown Seattle and from West Seattle will also be closed as well. It's as simple as this - I-5 is going to be a maze and it's going to keep changing.

Stage One starts Friday night, August 10.  On the first weekend, northbound I-5 will be down to two lanes. If you're coming from West Seattle, the Spokane Street on-ramp to Northbound I-5 will be closed. So will the downtown exits off I-5 to Dearborn, James, and Madison streets.

The lanes that will be open on I-5 will only be 10 feet wide, a foot narrower than usual.  And the one-mile stretch of highway will be without shoulders at some point, meaning any vehicles that stall or break down will cause even greater problems.

Also, you won't be able to get onto I-90 from northbound I-5 either.

"If you're coming from the very south end past Southcenter and the I-405 ramp, there will be a variable message sign across the freeway down there that will warn you that you can't get off at I-90 and that you need to take I-405," said Paul Johnson, Washington State Department of Transportation traffic engineer.

Stage Two begins Monday, August 13.  The West Seattle, I-90 and downtown ramps will be re-opened, but a couple of right hand lanes of I-5 will be closed.  So will the Columbia Way on-ramp from Beacon Hill.

"Stage two is much better.  You have the West Seattle on-ramp open, you have the northbound collector-distributor open, so you have more ramps," said Johnson.

But, don't be fooled.

"You have a third lane on I-5 that first week instead of the two that we had over the weekend," said Johnson. "Traffic is still going to be very slow.  It's going to be very congested."

Stage Three kicks in on the second weekend, August 18.  That's when construction crews switch to the inner lanes of I-5.  Again, the West Seattle and Columbian Way ramps will be closed for the weekend.

"After (drivers) have been through the first weekend and the first week, the second weekend they'll probably think 'I want to avoid I-5 if possible,'" said Johnson.

Stage Four is the second work week.  All you need to remember is that Monday and Tuesday, August 20-21, could be the worst, with all but one lane closed.

It should get a lot better by that Wednesday when more lanes are reopened.

Even if you don't use I-5 north, the spillover effect will likely be felt on all surrounding highways and streets.

"You may think you're not going to be affected because you commute from the east and only take I-90, but we are going to see some more congestion on I-90 because people are going to be taking I-405 to I-90," said WSDOT spokesperson Megan Soptich.

Officials urge people to use public transportation during the repairs, but there's a bit of a wrinkle.  While other agencies such as Pierce Transit are adding extra buses, Metro says it doesn't have any to spare and that's fleet is currently maxed out.

Work is scheduled to be finished by August 29.

The WSDOT will have a hotline to answer questions about the closures at 206-440-4704. It will be staffed from 7 a.m. to 6 p.m. until August 9. During the project, it will be staffed from 6 a.m. until 11 p.m.