WSDOT will begin working toward this objective in summer 2011 with construction of a 1,100-foot (335-meter)-long concrete snowshed and avalanche fencing.
The existing snowshed, built in 1950, only protects the westbound lanes from the two most active of the five chutes, leaving portions of the interstate vulnerable to snow from natural avalanches and avalanche control measures.
The new snowshed will protect the entire width of interstate from four of the avalanche chutes with an enlarged ditch providing a catchment area for the remaining minor chute.
"When the snowshed is complete, we hope to reduce those closures by 70 percent."
WSDOT will construct the snowshed using standard bridge design techniques.
"In addition to designing the snowshed around the area's unfavorable soil and rock slope conditions, weather limitations, and construction access, maintaining existing traffic levels during the construction phase will be challenging," Golbek says.