Envision Downtown will pilot new signs along Fort Duquesne Boulevard on Thursday that tell drivers how many spaces are available in the nearest garages. Three LED television screens, mounted on poles and picking up Wi-Fi through an attached hotspot, will display the number of available spaces next to the name of the garage, but if it’s full, will direct the driver to the next closest facility.  “We think we’ve hit on something really unique,” said Sean Luther, executive director of Envision Downtown. “We’re not aware of any other city doing parking garage wayfinding exactly like this, but it’s also a trial for us, too.” The system relies on data from the ParkPGH app, a project of the Pittsburgh Cultural Trust funded by the Benter Foundation that launched about five years ago. The Pittsburgh Cultural Trust estimates the Park PGH app has been used more than 550,000 times this year, but the new signs are a way to keep drivers off their phones as they search for spots.