If you're headed into Seattle this weekend, make sure to fill up the gas tank, use the potty beforehand and look for alternate routes. Bring your favorite tunes, a snack and whatever else you need to chill.

A Seahawks game on Saturday, four weekend-long highway road-construction projects and ramp closures in Seattle almost ensure a traffic situation, according to Washington State Department of Transportation officials.

"We're not saying don't go to Seattle," said Jamie Holter, a spokeswoman for the department. "It's going to be a gorgeous weekend, and there's a Seahawks game and so much to see and do, but what we are saying is don't expect it to be a regular day."

"What we are saying is, leave early."

Holter said the department is working to mitigate congestion working with cities to re-time the signals on arterials to keep traffic moving. Continual updates also will be posted and tweeted.

Nevertheless, she said, people should allow for at least one extra hour of travel time.

"We've packed a lot of construction into one weekend," said Lorena Eng, WSDOT regional administrator. "Drivers should check the Web, plan alternate routes, stay on top of changing traffic conditions, and be prepared for longer than normal travel times."

The closures will affect drivers in Renton, Seattle, Bellevue, Lake Stevens and Clearview in Snohomish County.

Here are the details:

The 520 floating bridge and all connecting ramps will be closed between Montlake Boulevard in Seattle and Interstate 405 in Bellevue from 11 p.m. Friday until 5 a.m. Monday while crews demolish the old Bellevue Way Northeast overpass and dig a 25-foot-deep trench to install a culvert beneath all lanes of the highway.

In Renton, Highway 167 will be closed between I-405 and South 180th Street from 7:30 p.m. Friday until 4:30 a.m. Monday while crews dig a 35-foot-deep trench to install a new culvert beneath the highway.

In Snohomish County, Highway 9 between Highway 524 and 180th Street Southeast in Clearview will be closed from 9 p.m. Friday until 2 a.m. Sunday, for the installation of a culvert. The detour route is eight miles long and will add 15 minutes or more to the usual trip.

The intersection of Highway 92 and Highway 9 near Lake Stevens will be closed from 10 p.m. Friday until 7:30 a.m. Sunday for paving.

Seattle will close the southbound I-5 offramp at 85th Street, north of Green Lake, from 10 p.m. Friday until Aug. 27, while westbound lanes are being repaved. Eastbound access from 85th to the freeway is already closed until Aug. 31. Lake Washington Boulevard East, inside the Washington Park Arboretum, will close from 7 p.m. Friday to 9 p.m. Sunday.

And the Ballard Bridge closes overnight from 11 p.m. Saturday to 7 a.m. Sunday, for lighting improvements.

The state has even gone so far as to provide tips on putting together a "traffic buster" survival kit.

Suggested contents include: string cheese for the kids, toilet paper, flares, emergency kits, "a venti Starbucks coffee" and music to help the driver tune out frustrations. The tips can be found on the department's Facebook page www.facebook.com/WSDOT.

For more information, see the department's website at:

www.wsdot.wa.gov/Construction/PugetSound/closures.htmwww.wsdot.wa.gov/traffic/seattle/products

or follow it on Twitter: @wsdot_traffic

Christine Clarridge: 206-464-8983 or cclarridge@seattletimes.com