Mirror staff reports:

Washington State Department of Transportation crews will close all lanes of I-5 at SR 18 at night Feb. 24-25 to install girders over the freeway in Federal Way.

All southbound lanes and two northbound lanes will be closed Friday, Feb. 24, from 11 p.m. to 7 a.m. All northbound lanes will be closed Saturday, Feb. 25, from 11 p.m. to 7 a.m.

Drivers should expect delays of up to 30 minutes. Please see a detour map on this page (or click here).

This is the third weekend closure in February for the interchange. The new flyover ramps are part of the Triangle Project, which refers to the interchange in Federal Way where Highway 161 (Enchanted Parkway), Highway 18 and Interstate 5 all meet. The interchange has long held a reputation for being dangerous for drivers. Federal Way and King County officials have been working to fund the project for more than a decade.

The project is slated for completion by the fall of 2012, but the new ramps are expected to open this summer.

The project will eliminate the current cloverleaf loop ramps and replace them with flyover ramps for westbound Highway 18 to southbound I-5 and eastbound Highway 18 to northbound I-5. Direct access will be provided to Highway 161 from southbound I-5 and westbound Highway 18 through the construction of new exit ramps at South 356th Street and South 359th Street in Federal Way.

The project is expected to improve existing and future traffic flow; reduce the number and severity of accidents in the vicinity of I-5, Highway 161 and Highway 18; and avoid or reduce the effects on the environment. Approximately 3,600 freight trucks — many coming to or departing from Federal Way — use Highway 18 to access Interstate 5 daily, according to WSDOT numbers. The flyover ramps will cut down on the time it takes freight haulers to complete their runs.