The last of three total nighttime closures of I-5 in Federal Way begins Friday night.

Crews working for the Washington State Department of Transportation are installing steel girders for two new flyover ramps at the I-5/SR 18 interchange. The work will require nighttime closures as cranes lift the large bridge girders over the highway.

This weekend’s closures are as follows:

Friday to the morning of Saturday

Crews will close all lanes of southbound I-5 and two lanes of northbound I-5 at SR 18. Lanes will begin closing at 9 p.m., with all lanes closed at 11 p.m. All lanes will reopen by 7 a.m. Saturday.

• Southbound I-5 detour: Drivers will follow a five-mile detour along Highway 99 to 54th Avenue E. in Fife to rejoin southbound I-5.

• Crews will close the following ramps from 9 p.m. to 7 a.m. – The westbound SR 18 off-ramp to southbound I-5; the southbound I-5 off-ramp to eastbound SR 18.

Saturday to the morning of Sunday

Crews will close all lanes of northbound I-5 at SR 18. Lanes begin closing at 9 p.m., with all lanes closed at 11 p.m. All lanes will reopen by 7 a.m. Sunday.

• Northbound I-5 detour: Drivers will be detoured onto eastbound SR 18 to Weyerhaeuser Way, then to westbound SR 18 to rejoin northbound I-5.

• Crews will close the following ramps from 9 p.m. to 7 a.m. – The eastbound SR 18 off-ramp to northbound I-5; the northbound I-5 off-ramp to westbound SR 18.

Please note: Partial nighttime closures of I-5 will continue next week.

For more information, please visit: www.wsdot.wa.gov.

The work is part of a $112 million project to build two new flyover ramps – one between westbound SR 18 and southbound I-5, and the other between eastbound SR18 and northbound I-5. The ramps are expected to open by the end of this year.

For more information on the project, go to: www.wsdot.wa.gov/projects.