SW Thomas between SW 52nd Place and Shattuck Road is public right of way in the City of Portland but it is an unimproved road and the maintenance of the road is the responsibility of the adjacent private property owners. To request some sort of signage indicating "local access only" or "unimproved road", etc. contact the City of Portland Traffic Safety Division at safe@portlandoregon.gov, 503-823-SAFE.