Rocky Butte Slope Paving Failure Response

What's Happening Now

[Updated June 23, 2026] 

PBOT crews will begin repairing the hillside from erosion, requiring the closure of one lane of NE Rocky Butte Road starting this Friday, June 26. Repair work is expected to last all hours, all days, through the end of the summer. 

To avoid travel delays, visitors to Rocky Butte Park should enter and exit from the north, via NE Fremont and 91st Avenue. 

To ensure safety and limit traffic congestion during the closure, PBOT will post Local Access Only signs directing travelers to avoid entering the area from the south, via the intersection of NE Russell Street, NE 92nd Avenue and NE Rocky Butte Road. Local access to houses uphill and downhill from the work zone will be allowed. 

View full size image of Visual map showing recommended access point to Rocky Butte Park at NE 91st Ave and Fremont St.

Planned work

The removal and replacement of the slope paving and foundational base will be conducted in the following phases:

• Clear plant growth and debris and remove the temporary concrete Ultra block catchment barrier wall at the bottom.
• Remove the existing slope paving (wall) stones and transport to PBOT facilities for potential re-use on future area repairs.
• Conduct slope preparations and excavation ahead of construction of the new retaining wall foundation.
• Once retaining wall concrete has cured, install a new stone-filled gabion mattress system and drainage mitigation features.

Background

Rocky Butte, originally known as "Mowitch Illihee" to the indigenous Chinook Tribe, is widely known for its historic stone construction throughout the area which includes Joseph Wood Hill Park, Rocky Butte Tunnel and numerous stone retaining walls and slope paving (stones laid against slopes to protect from erosion) along NE Rocky Butte Road. 

In 2019, a small area of slope paving was showing signs of imminent failure with dislodged stones, voids and lateral movement of the base. After consultation with geotechnical engineers, PBOT selected an updated repair plan which meets current engineering standards, rather than replacing the existing system in-kind.

The historical nature of this location required additional consultation from local Native Tribes which include the Grande Ronde, Siletz and Warm Springs. A Memorandum of Agreement between PBOT and the State Historic Preservation Office was also required before construction could begin. 

Design details

The new stone-filled gabion mattress system will make use of natural stones to harmonize with the existing adjacent historic stonework and then be wrapped in an engineered metal fabric for increased stability. The updated system will be founded on a concrete footing to create a solid foundation.

View full size image of An example of a stone-filled gabion mattress system proposed for the project location.