Roadway Ruts Worsening On Interstate 90
Some springlike sunshine has shed light on the grooves Spokane Valley freeway commuters have been feeling all winter.
The roadway ruts along Interstate 90 between the Sprague Avenue and Pines Road interchanges often send vehicles lurching about before they settle into a path that typically favors one side of the lane or the other.
Relief for drivers of the region’s busiest thoroughfare is at least another winter away.
The five-mile stretch is among several projects included in the budget the state Department of Transportation submitted to the Legislature for approval for the next biennium. The budget proposal shows plans to resurface that badly rutted stretch of I-90 during the winter of 1998-99, at a cost between $1 million and $2 million.
A widening project, planned to be completed over the next several years along that stretch, should help lessen future wear by spreading the load over additional lanes. Concrete lanes also will be built between the Sprague and Argonne interchanges as part of the widening work. Lanes from Argonne to the Pines interchange will be resurfaced with asphalt.
Studded snow tires grinding against bare roadway, heavy truck traffic and the large volume of commuter traffic all have contributed to the “accumulated wear” problem, said Al Gilson, state DOT eastern region spokesman.
The stretch was last resurfaced in 1990.
Since then, inside tires on semi-trucks and trailers have helped cars with studded snow tires wear two distinct ruts along the over-used asphalt section, Gilson said.
State traffic engineers estimate 105,000 cars travel that stretch of I-90 daily.
“We are literally wearing this pavement out at an accelerated rate,” Gilson said.
A study of studded snow tire wear factors conducted in Alaska and Sweden recently found that pavement wear rates average .13 inches per million studded tire passes, Gilson said. Cars with four studded tires make two passes per one-way trip.
About 25 percent of the cars in Eastern Washington are equipped with studded tires, meaning that wear rates along the Valley’s stretch of the I-90 corridor could approach one-quarter inch per year.
“Studded tires are really causing us some grief,” Gilson said.
Ten miles of rutted freeway between Pines and the Idaho border was repaved two years ago for about $1.3 million.
A porous asphalt mix that was put down in 1991 to control tire spray, and offer a quieter, smoother, and safer drive did did not stand up to the demands of the heavily used roadway. It was expected to last eight years, but lasted only half that long before being replaced with a harder, standard-grade asphalt.
The ruts between Sprague and Pines are not related to that problem, Gilson said.
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