Spotted this on the Pine/Spruce bike lanes the other day. I’ve never seen a sign like that before; a friendly way to get people to drive slower. More of a suggestion than a command.
To elaborate, this sign indicates that a slow car or speedy bicycle can get from Second St. to Broad St., and then from 15th St. to 23rd St. with all green lights, traveling at 20 MPH or so. Many of the traffic lights in the city are timed this way, but this is the first street to actually call it out.