When the Oregon Department of Transportation decided to fast-track the Interstate 405 preservation project this past summer to complete a much-needed upgrade, the road agency was well aware of the pain it would cause the daily 83,000 to 125,000 motorists who use this vital 5-mile spur that runs from the Freemont Bridge to the Marquam Bridge, but ODOT also knew it was the best solution to minimizing traffic disruptions.

For almost 40 years the original concrete road structure had served the Portland area well, but severe rutting posed safety issues and there was no way to avoid the major undertaking required to support the heavy traffic load this major thoroughfare needs to accommodate.

The project involved filling the rutted surface with a hot-mix leveling course and then placing a final wearing course of asphalt over the entire travel lane sections of the road, along with inlaying the on- and off-ramps servicing the interstate to improve the overall safety and ride smoothness of the road structure.

Pavement grinding under four over-crossings of the freeway also had to be coordinated to maintain federal clearance requirements. New lighting and signs along the corridor were also included in the rehabilitation project.

As one of the busiest sections of freeway in the Portland metro area, serving freight and commuter traffic, the preservation project was a top priority for ODOT during the 2009 construction season.

The high traffic volumes during weekday daytime hours required that the travel lanes remain open. It was determined that any closures during that time would only result in significant backups on I-405, I-5 and local streets. Consequently, it was decided that four weekends of full directional (northbound and southbound) closures would accommodate the milling and asphalt overlay work required and eliminate months of nighttime construction that would normally be required for this type of project.

The milling and asphalt work was completed during three weekend single-directional (north or south) closures in August and one weekend single-directional closure in September, with additional nighttime lane closures required to complete some ramp paving, lighting and sign work. The weekend directional closures were limited from 10 p.m. Friday to 5 a.m. Monday.

Kerr Contractors Inc. of Woodburn, OR, served as the primary contractor on the $11.6 million project, with Knife River Corp. performing all of the paving work, placing 25,000 tons of asphalt.

The project also called for 150,000 feet of striping, 11,000 cubic yards of backfill, 15,000 square feet of concrete surfacing to cover the concrete median barrier, approximately 40 manholes and 90 storm water inlets raised to grade, 220 new light poles, as well as new lighting within tunnel structures, and two new sign bridges to be installed. Approximately 30% of the project cost was covered by stimulus funds through the American Recovery and Reinvestment Act.

Orchestrating the symphony

Ron Larson, ODOT Region 1 project manager overseeing the I-405, says while the directional closures did allow for an all-out construction effort during four 55-hour intensive work weekends, it required a well-orchestrated effort on the part of everyone involved.

"We had milling and paving going on at the same time, as well as other subcontractors (electrical, striping, etc.) working on their specific parts of the project," Larson explains. "While we didn't have to deal with motorists during the closures, we still had a lot of traffic and activity in the construction zone and safety was primary concern with all the moving parts of this project."

With severe rutting (1/2 to 3/4 in. deep) throughout the entire project, diamond grinding was required on some of the worst rutted areas as well as under four critical over-crossings.

"We would set up paving operations in an area that didn't require grinding in order to maximize progress during the closures," Larson explains.