It's expected to be a major step towards solving the decades-long "Mercer Mess" that has plagued the area near Interstate 5.
The new roadway will accommodate three lanes of westbound traffic that will travel straight off the I-5 off-ramps.
Eastbound Mercer Street will maintain three lanes onto the I-5 on-ramps, in addition to a left turn lane onto northbound Fairview Avenue North and travel across Fairview Avenue North that allows eastbound access to Eastlake and Capitol Hill.
Drivers told KOMO News they are happy this project is now halfway complete.
This begins the third of four construction stages on the Mercer project. The third stage is expected to last through early 2013.
Traffic restrictions will be in effect during State 3, including the following:
One northbound travel lane on Fairview Ave. N between Harrison and Valley streets
No access to Fairview Ave. N via Republican St. and no southbound access at the I-5 off-ramps at Mercer St.
One southbound lane on Fairview Ave. N from Aloha St. that connects to westbound Valley St.
Valley St. closed to eastbound traffic east of Terry Ave. N
Access maintained to Lake Union Park and businesses in Chandler's Cove
Work to be completed during the third stage of construction includes undergrounding of electrical distribution, transmission and communication lines; replacement or relocation of water, sewer, and storm drainage systems; relocation of gas lines; widening Fairview Ave. N between Republican St. and Valley St.; and the installation of new pavement, sidewalks, signals, lighting, signage, intelligent transportation systems, landscaping and urban design features.
For more information about the Mercer Street construction project, visit the Seattle DOT website >>