Via the increasingly indispensible Streetsblog, this story about how Philadelphia is planning to paint optical illusions on streets around town to slow down drivers. They’re cheaper than speedbumps, apparently, and they have the added benefit of scaring the bejesus out of drivers who suddenly see three triangles floating in front of them. Why stop with triangles? Imagine how effective trompe l’oeil dragons, or maybe a realistic portal to hell would be?

If you own a fruit stand in Philadelphia or are engaged in the business of moving large panes of glass across the street, this may be cause for concern.