Road crew discovers old timber road


Environmental Science Associates (ESA) archaeologist recording a segment of corduroy (split log) road. Photo credit: Tom Minichillo

When the King County Road Services Division (Roads) builds projects, it takes into account the effects of the project on cultural resources. Cultural resources are historic places, buildings and archaeological sites – places important to the history or prehistory of the county. In order to ensure cultural resources are properly identified and protected, field staff complete in depth training run by professional archaeologists and historic preservationists and great care is taken to comply with all federal, state and local laws, rules, regulations and policies related to cultural resources. Roads employs a full-time professional archaeologist to coordinate cultural resource efforts. All of these factors came together last fall when remnants of a timber roadway were uncovered in the middle of a large roadway construction project.


Representatives from Roads, WSDOT, DAHP and ESA on site to discuss plank road find under the West Snoqualmie Valley Road NE. Photo credit: Katie Merrell

The West Snoqualmie Valley Road NE Reconstruction Project in September 2016 included rebuilding a segment of road located between NE 80th Street and Ames Lake Road NE, in unincorporated King County, near the community of Vincent. One of the reasons the road was being reconstructed was its poor subgrade. During the excavation of the existing subgrade, contractors discovered a solid timber layer of road where they had been digging. After alerting King County inspectors and the archaeologist to the situation, the grading in that area was stopped. Upon further inspection, the buried timbers were found to be a plank road, made up of cedar planks 32 feet long and 12 inches wide. The planks were nailed together with wire nails and spikes. Because this project was subject to the National Historic Preservation Act, the Washington State Department of Transportation (WSDOT) and the Department of Archaeology and Historic Preservation (DAHP) were brought in to map out a way forward for the project.


A section of plank road exposed by vactoring. Photo credit: Tom Minichillo

The buried timber roadway was immediately determined to be eligible for the National Register of Historic Places. Although the buried segment of intact plank road is historic, preservation in place was not recommended because wood in the subgrade of a modern roadway will eventually deteriorate, creating voids in the pavement and leading to accelerated roadway deterioration and failure. An agreement among the agencies was quickly created to record the wooden road elements before removing them and to conduct additional archival research.


Exposed profile of buried plank road showing woody debris under the old road bed. Photo credit: Alicia Valentino

After the section of plank road was recorded, another section of timber road, this time split cedar logs called corduroy road, was found. This section of buried timber road was also recorded. None of the timber roadway could be preserved in place and it was all removed, with new subgrade installed. After being buried for 80 years in wet conditions the wood was not salvageable for reuse and was recycled as mulch.


ESA archaeologist exposing buried plank road by hand. Photo credit: Tom Minichillo

Both segments of timber road were part of the private farm road that is first documented in 1906 and established as a County Road in 1933 as the Solberg Connection Road. The different types of timber road construction aligned with the property lines of the dairy farms along the road. In 1935 the county buried the old timber roadway as part of the grading and paving of the new county road. Due to the quick actions and support of all agencies involved, the contractor was able to work on other parts of the project while the buried roadway was recorded, resulting in no changes to the project schedule.

For media inquiries, contact Brent Champaco at or (office) 206-477-9094 or (cell) 206-573-4267.

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