TULALIP – Work is scheduled to start July 20 on a Tulalip Tribes project to improve the interchange of I-5 and 116th Street NE.

From 7 p.m. to 6 a.m. weekdays, up to two lanes in each direction of I-5 at 116th will close, and traffic will shift for a center work zone. This phase of the project will replace the 116th Street bridge over I-5 with a wider bridge to include more traffic lanes as well as bike lanes and sidewalks.

Dates will be posted on the affected ramps 5 days prior to any closure. At least one lane will be open to traffic at all times on mainline I-5 and 116th Street. The project will be done in September 2016. Granite Construction began shoulder closures last week to install construction signs and for erosion/sediment control measures.

The state says the bridge built in 1971 causes backups on I-5 and has stifled economic development in the area. The fix will cost $43.1 million and reduce accidents, delays and gas emissions. For every $1 spent, $29 will be generated, it says.