Friday the 13th will bring a major closure to southbound Interstate 5 in Federal Way, where the HOV lane will close for 10 days straight.

Crews working for the Washington State Department of Transportation (WSDOT) will close the southbound I-5 HOV lane just south of State Route 18 around the clock from 7 p.m. Fri., May 13, to 1 p.m. Mon., May 23. The work is part of the I-5/SR 18/SR 161 Triangle Improvement project.

“This area of southbound I-5 typically isn’t very congested except on Friday afternoons,” said Aleta Borschowa, project engineer. “With the HOV lane closed, we expect weekday afternoon commutes to look like a Friday afternoon. That means speeds of 35 to 40 miles an hour and delays of about ten minutes.”

Nearly 8,000 vehicles per hour use southbound I-5 in Federal Way during the peak afternoon commute. About 1,000 of those use the HOV lane.

The closure will allow crews to cut open the pavement on the left shoulder and dig 13 feet below the surface to install a system to catch and treat highway runoff. Because the pavement will be cut open, the work needs to be done with an around-the-clock closure.

Construction on this stretch of I-5 through Federal Way has increased during the past several months. So far, crews have built 13 of 26 bridge columns that will eventually support two new flyover ramps; the ramps will carry traffic from westbound SR 18 to southbound I-5 and from eastbound SR 18 to northbound I-5. These new ramps will eliminate lane weaving that can lead to congestion and collisions at the busy I-5/SR 18 interchange.

The HOV lane closure is the first of a series of significant closures during the next few months. Starting the day after Memorial Day, crews will close the ramp from Weyerhaeuser Way to westbound SR 18 for three months. Then in August, the westbound SR 18 ramp to northbound I-5 will be closed for approximately four weeks. These closures will allow crews to rebuild the ramps to accommodate the flyover ramp from westbound SR 18 to southbound I-5. Signed detours will be in place. Drivers can stay ahead of construction by signing up for the South King County email update, following WSDOT on Twitter, checking the project Web site or calling the 24-hour project hotline at (206) 440-4900.

This $112 million project, which began last August, is expected to be completed in late 2012.