Clark - NW PACIFIC HWY
Project Number: 1540
From milepost 1.34 to milepost 1.72
RATA Funds: $1,590,176
Legislative District: 18
Status:
Date Approved: 2008
Pacific Highway is a vital link to our transportation network in southwest Washington and serves local traffic, creates an alternate north-south route to I-5 during emergency detours, and provides adequate clearance to oversized vehicles restricted by the Lewis River and East Fork Lewis River bridges on I-5.
A section of Pacific Highway has a long-term, slow-moving slide. The slope has been consistently moving approximately ½ inch a year since monitoring began in 1999 when inclinometers were installed. Due to the significant movement, several of the inclinometers were sheared off and replaced in 2005. The movement of the slide caused the north side of the roadway to have minor to major cracking and the roadway to sink in places.
Previous efforts to repair the roadway resulted in several overlays creating six to eight feet of asphalt over the original concrete road. The existing roadway measured 24.5 feet wide, roughly four feet under the required width of 28 feet.
The design goal was to repair and preserve the roadway while allowing the slide to continue to move. The selected alternative placed a deep patch consisting of layered fabric and rock finished with asphalt which is anticipated to last up to 10 years. The intent of the deep patch is to create a strong and flexible road crown/pavement section that is capable of withstanding some slide movement without excessive distress developing. Testing and inspections shows that the slide is continuing to move without the road surface cracking. Other improvements included road widening to include two 12’ lanes with 2’ shoulders, a replacement culvert and guardrail.
A section of Pacific Highway has a long-term, slow-moving slide. The slope has been consistently moving approximately ½ inch a year since monitoring began in 1999 when inclinometers were installed. Due to the significant movement, several of the inclinometers were sheared off and replaced in 2005. The movement of the slide caused the north side of the roadway to have minor to major cracking and the roadway to sink in places.
Previous efforts to repair the roadway resulted in several overlays creating six to eight feet of asphalt over the original concrete road. The existing roadway measured 24.5 feet wide, roughly four feet under the required width of 28 feet.
The design goal was to repair and preserve the roadway while allowing the slide to continue to move. The selected alternative placed a deep patch consisting of layered fabric and rock finished with asphalt which is anticipated to last up to 10 years. The intent of the deep patch is to create a strong and flexible road crown/pavement section that is capable of withstanding some slide movement without excessive distress developing. Testing and inspections shows that the slide is continuing to move without the road surface cracking. Other improvements included road widening to include two 12’ lanes with 2’ shoulders, a replacement culvert and guardrail.