SEATTLE -- Traffic remained steady through the construction zone in the northbound lanes of Interstate 5 from Tacoma to Seattle on Sunday and the construction project was right on schedule.

Traffic was slightly slowed on Sunday afternoon as more cars hit the road. Traffic slowed to an average of 13 mph around 3:30 p.m., but the thickening traffic did not cause a backup outside the construction zone, officials said. City traffic officials said the traffic volume on city streets did not seem affected by the construction.

Meanwhile, crews continued to replace the expansion joints on the Interstate 90 exit as well as the joints near Spokane Street.

Crews also used a giant blow dryer to manually dry out the roadway in order to keep to the repaving schedule. The tool was used on the bridge deck in the north end of the construction zone following the early-morning mist on Sunday.

"It's got a fan on it like a jet engine that runs it and it burns lots of fuel - over two-hundred gallons an hour," said Paul Johnson with the department. "So, you're getting a lot of power there and a lot of wind blowing down the pavement - we can dry the area out in 20-to-30 minutes."

Three northbound lanes of I-5 were closed on Friday night in preparation for the repaving work, as well as the Columbian Way ramp to northbound I-5, the West Seattle freeway and Spokane Street on ramps to northbound I-5 and the northbound I-5 ramp to I-90 and Dearborn. The closures will remain in effect through the weekend.

The I-5 express lanes are operating southbound all weekend.

The speed limit through that segment of freeway will be 45 mph during the entire project. There will be no high-occupancy-vehicle lane in the construction zone. The HOV lane will be shifted to Airport Way, but only trucks, buses, van pools and emergency vehicles will be allowed to use the lane.

What to expect on Monday morning

The second phase of the project begins on Monday, which means one northbound lane and several on ramps will reopen.

Crews are trying to finish paving work on the north end of the construction zone before the Monday morning commute to allow drivers to gain eastbound access to I-90 from northbound I-5.

At 5 a.m. on Monday, a third northbound lane of I-5 will be reopen to traffic, as well as the on ramp from West Seattle and Spokane Street. The 4th Avenue South off ramp, however, will be shut down. Those headed to the Mariners game are urged to find alternate transportation.

Transportation officials said Saturday's traffic was approximately 55 percent lighter than the load expected on a normal Saturday. The longest traffic backup on Saturday extended from the work zone to Spokane Street, which means, at the longest, it took drivers ten minutes to get through the construction are.

Officials said the change in traffic flow indicates many of the drivers have taken early measures to avoid the construction area and find alternate routes.

But the full effect of the construction project on traffic may not be known until Monday morning, when weekday commuters will face the major hurdle on the roadway for the first time. The disruption affects some 126,000 drivers who may be significantly delayed if not enough drivers manage to find an alternate route or an alternate form of transportation.

"We still need half of the drivers that normally use northbound I-5 to take an alternate route or ride the bus, car pool - anything that they can do to help us," said Laura Johnson with the department.

Transportation officials said in the worst-case scenario, traffic backup could stretch as far as 30 miles in the northbound lanes of I-5 if most drivers who use the roadway daily do not change their routine.

In the best-case scenario, if the majority of drivers will use alternate transportation or avoid the roadway altogether, traffic might be sluggish through the construction zone, but continue moving, officials said.

Alternate routes to seek, alternate routes to avoid

There are several alternate routes drivers can take in order to avoid the stretch of I-5 from Tacoma to Seattle. They include:

• Airport Way S.
  
• Fourth Avenue S.
  
• First Avenue S.
  
• Alaskan Way S.
  
• SR 99 I-405
  
• East Marginal Way

Drivers should note Rainier Avenue in Renton is not a suitable alternate route, as another construction project will keep the remain closed until August 15.

On Saturday, a contractor began tearing down an old bridge over the roadway. The bridge construction is necessary to transport fuselages for the Boeing 737-900 from Wichita to the Renton Assembly plant. The 900 is too large for the present bridges.

Transportation officials said traffic volume was up by 15 percent on Interstate 405 at NE 30th Street on Saturday, which they believe to be the result of the Rainier Avenue closure.

For More Information:

Check our online traffic section for continuing coverage of the I-5 construction project, get your questions answered by KOMO traffic reporter Jenni Hogan, and check travel times, live cameras and more:

http://www.komotv.com/traffic