If the weather cooperates, Washington State Department of Transportation (WSDOT) crews will make a major step forward this weekend in the Interstate 5/State Route 16 Eastbound Nalley Valley project in Tacoma.

Beginning at 10 p.m. on Fri., Jan. 3, crews will begin the process of relocating eastbound State Route 16 traffic from a temporary viaduct onto the new permanent viaduct near Interstate 5. The work requires numerous day and night lane closures of eastbound State Route 16 and the southbound Interstate 5 exit to South 38th Street. In the event of inclement weather, the work and closures will be rescheduled.

WSDOT encourages drivers to plan a strategy to deal with potentially long daytime delays and heavy congestion on eastbound State Route 16. On a typical weekend, this stretch of eastbound State Route 16 is traveled by more than 100,000 vehicles. WSDOT traffic engineers warn that without a reduction in traffic during the restrictions, eastbound backups could reach the Tacoma Narrows Bridge, which is six miles away. Sunday is anticipated to have the heaviest traffic congestion.

Here are the closure specifics:

Fri., Jan. 3 @ 10 p.m. — Close all lanes of eastbound State Route 16 at South Union Avenue (detour via Union); Close South Union Avenue on-ramp to eastbound State Route 16; Close southbound Interstate 5 exit to South 38th Street.

Sat., Jan. 4 @ 7:30 a.m. — Open two lanes of eastbound State Route 16. One lane will take motorists to northbound Interstate 5; the other lane will take motorists to southbound Interstate 5; Open South Union Avenue on-ramp to eastbound State Route 16; Open southbound Interstate 5 exit to South 38th Street.

Sat., Jan. 4 @ 10 p.m. — Close all lanes of eastbound State Route 16 at South Union Avenue (detour via Union); Close South Union Avenue on-ramp to eastbound State Route 16; Close southbound Interstate 5 exit to South 38th Street.

Sun., Jan. 5 @ 11:30 a.m. — Open one lane of eastbound State Route 16, detour all eastbound State Route 16 traffic onto southbound Interstate 5. Motorists wishing to reach northbound Interstate 5 will be detoured via South 56th Street interchange; Open South Union Avenue on-ramp to eastbound State Route 16; Open southbound Interstate 5 exit to South 38th Street.

Sun., Jan. 5 @ 10 p.m. — Close all lanes of eastbound State Route 16 at South Union Avenue (detour via Union); Close South Union Avenue on-ramp to eastbound State Route 16; Close southbound Interstate 5 exit to South 38th Street.

Mon., Jan. 6 @ 4 a.m. — Open all ramps and roadways. Eastbound State Route 16 motorists will be driving, for the first time, on the new permanent eastbound State Route 16 viaduct.

*****UPDATE | Thurs., Jan. 2, 2014 @ 3:14 p.m. — In addition to this weekend’s day and night lane closures on eastbound State Route 16 in Tacoma, WSDOT has announced there will be a full closure tonight. Beginning at 11 p.m. on Thurs., Jan. 2, all lanes of eastbound State Route 16 at South Union Avenue will close along with the South Union Avenue on-ramp to eastbound State Route 16. Traffic will be detoured through South Union Avenue. All lanes of eastbound State Route 16 at Union Avenue, as well as the South Union Avenue on-ramp to eastbound State Route 16, will re-open at 4 a.m. on Fri., Jan. 3.

Work of this magnitude is typically scheduled at night to minimize impacts to drivers. However, once crews start on this phase of the project, they must continue until it’s complete. Because of the anticipated lengthy traffic backups on both Saturday and Sunday, Contractor Mowat Construction is considering ways to expedite the work. While the work is underway, motorists are encouraged to find alternative routes and reschedule or eliminate discretionary trips. WSDOT encourages drivers to visit tacomatraffic.com online for up-to-date information so they can be informed about traffic conditions before leaving home.

Once the traffic shift is complete, crews will demolish most of the temporary viaduct. A segment on the west end of the viaduct will remain and will be used in a future project to build a viaduct for high-occupancy-vehicle (HOV) traffic. Crews are shifting traffic from a temporary viaduct to a permanent viaduct. Once the traffic shift is complete, crews will demolish most of the temporary viaduct.

The work is a part of the $115 million Interstate 5/State Route 16 Eastbound Nalley Valley project and the $217 million Interstate 5/State Route 16 Realignment – HOV Structure and Connections project.

More information is available online here.