The busy Interstate 5/US 101 interchange in Olympia will be the focus of vital bridge structural repair work over the weekends of Sept. 12 and Sept.19. Preparations for the two weekends will require lane and ramp closures each Thursday night, Sept. 11 and Sept. 18.

Over a typical weekend, more than 276,000 vehicles use this stretch of I-5. Roughly 190,000 vehicles travel on US 101 approaching I-5. WSDOT traffic engineers warn that drivers likely will face lengthy backups and delays because no convenient alternate state routes are available.

Even with traffic volumes decreasing by 30% over the two weekends, traffic models show backups reaching 14 miles, with especially heavy congestion expected on southbound I-5.

Sept. 11 night closures

Starting Thursday, Sept. 11, motorists will encounter night closures on I-5 and US 101 as crews restripe I-5 lanes toward the highway median. At 8 p.m., crews will close the left northbound I-5 lane approaching Deschutes Way Southwest. At 10 p.m. they will close a second northbound I-5 lane and two ramps: 1) the southbound US 101 exit to northbound I-5; and 2) Deschutes Way Southwest to northbound I-5. US 101 motorists will be detoured onto southbound I-5 and through the Tumwater Boulevard interchange to reach northbound I-5.

The I-5 lanes and the US 101 ramp will reopen at 5 a.m. Friday, Sept. 12. The Deschutes Way Southwest on-ramp to northbound I-5 will remain closed through Monday morning, Sept. 15.

Sept. 12-15 closure details

Drivers can expect major lane and ramp closures along both directions of I-5 near Capitol Lake between 7 p.m. Friday, Sept. 12, and 5 a.m. Monday, Sept.15.

I-5 will be reduced to one lane in each direction between 10 p.m. and 8 a.m. Friday, Sept. 12 through Sunday, Sept. 14. During the daytime hours on Saturday and Sunday, I-5 will be open to only two lanes in each direction.

Ramp closures and reductions

The Deschutes Way Southwest on-ramp to northbound I-5 will close from 10 p.m. Thursday, Sept. 11, to 5 a.m., Monday, Sept.15.

The Henderson Avenue/14th Avenue Southeast on-ramp to southbound I-5 will be closed from 10 p.m. Friday, Sept.12, to 5 a.m., Monday, Sept.15.

US 101 on-ramp to northbound I-5 will be reduced to one lane from 10 p.m. Friday, Sept.12, to 5 a.m., Monday, Sept.15.