Somewhere along the bike path between Lanesborough and Cheshire, are set two concrete posts like this, both inscribed with large, white 'W's. To quell the obvious suggestion, they are on the east side of the north/south path.
The Ws are inscribed on the southern side of the posts, visible only to the northward-bound traveler. They are a mile --maybe two-- apart, but seem to have no relationship to distance, which the path clearly has marked: both in miles and separately in kilometers. There seem to be no real associated objects or phenomenon.