By Bill Sheets Herald Writer
LYNNWOOD — The rough stretch of pavement on southbound I-5 through Lynnwood has been that way for more than a year and will remain so until next spring.
The one-mile stretch of ground-down pavement from I-405 to 196th Street SW was scheduled to be repaved after the nearby, $33.7 million ramp project was finished in early October. Weather, however, has not cooperated, state transportation officials said.
Conditions have to be both warm and dry for fresh asphalt to settle and harden properly, said Cathy Arnold, a project engineer for the state Department of Transportation.
“We’d get one and we wouldn’t get the other,” she said of the necessary weather conditions. The project, in which new ramps were built to reduce weaving by drivers and increase safety, began in August 2010. Part of the asphalt had to be ground down to allow for reconfiguring lanes as part of the project.
The state has received very few complaints about the rough pavement, not even last holiday season when traffic volumes in Lynnwood were higher than normal, Arnold said.
“It’s not potholing. I keep waiting for people to say, ‘Why haven’t you done this yet?’” she said.
Now, southbound I-5 drivers exiting at 196th enter the off-ramp at the I-405 underpass, so they miss the coarse stretch of pavement altogether.
The other part of the section shaved off last year was a stretch of experimental quiet asphalt laid down in 2006 that was beginning to crumble, officials said.
The section was made of a rubberized asphalt composed partly of old tires, as opposed to the petroleum-based substances used in regular asphalt. The experimental pavement has more holes to absorb sound, but those holes also gather water. In the winter, that water can freeze and expand, helping break apart the asphalt, state transportation engineers have said. The asphalt’s quick deterioration also kept it from performing well as a sound muffler.
Another stretch of experimental quiet pavement, from 196th Street SW to 44th Avenue West, is made of a synthetic polymer. This material has performed better than the rubberized asphalt, officials have said — it has not deteriorated as quickly and held up better noise-wise, though the difference is undetectable by the human ear.
Quieter pavement was tested as an alternative or a supplement to noise walls. The walls reduce noise 5 to 10 decibels and have an expected life of 75 years but cost nearly $4 million per mile and block views, officials said.
The Lynnwood stretch of quieter pavement was laid down in 2006 as part of a $6.5 million repaving of southbound I-5 from south Everett to Mountlake Terrace.
Bill Sheets: 425-339-3439; firstname.lastname@example.org.