I-405 South Bellevue Widening
Atkinson widened four miles of I-405 within the City of Bellevue between 112th Avenue SE and SE 8th Street to six lanes. Crews constructed a new northbound lane from 112th Avenue SE to SE 8th Street, a new southbound lane from SE 8th Street to I-90, a new southbound I-405 mainline bridge over I-90, and widening several mainline bridges. In addition, we repaired pavement in both directions, installed a new ramp meter at 112th Avenue SE, restored the Kelsey Creek wetland, installed new ITS infrastructure, and provided many other improvements.
As part of the widening project, crews tore down the old Wilburton tunnel, a cast-in-place concrete tunnel supporting an abandoned rail line that restricted traffic flow to four lanes. Due to the high volumes of traffic on this urban transportation corridor (170,000 vehicles per day) and the requirement for a complete closure of the I-405 southbound lanes, a comprehensive Public Outreach effort was vital to the success of this major project milestone.
The public outreach program included a year-long information campaign to local businesses, residents, drivers, the media and others. Thanks to this concerted outreach effort and comprehensive planning, drivers avoided the area and the demolition was completed in only two weekends, instead of the allotted three. The team was also able to use the closure periods to piggyback other key project activities, such as dowel bar retrofitting, diamond grinding, PCC roadway panel replacement, roadway embanking and ramp drainage in an existing paved intersection, and the new SB I-90 mainline bridge approach tie-in. The completion of these activities during the weekend closures eliminated six weeks of nighttime lane closures for concrete rehabilitation and four maintenance of traffic shifts.
The project team earned two Roadway Work Zone Safety Awareness Awards from the American Road & Transportation Builders Association's Transportation Development Foundation for their jobsite and community outreach efforts.