Our answer:
Dear Tom,
I believe the device you see is from Toole Design Company. We (NVRPA) has contracted out with them to conduct a study of various trail intersections and Sterling Blvd was one of six intersections slated for study. The other five are Wiehle Avenue in Reston, Columbia Pike in Arlington, Hunter Mill Road, Belmont Ridge Road in Ashburn, and I’m drawing a blank on the last one (Lee Highway??).
In any case let me know if you have further questions. Thanks,
Karl Mohle
Park Manager
W&OD Railroad Regional Park