A bench in Zürich, conspicuously rubbed with wax by skateboarders... reduced friction, makes is easier to grind the bench.

Why do I blog this? The tweaking of urban elements in an interesting practice to observe. What does that say about urban computing? possibly that a certain audience can modify the infrastructure they need to operate with regards to their needs. At the social level, the presence of wax on curbs/bench is also a trace of people activity, a social navigation indicator that skateboard hang out there. I recently wrote a short article about that topic for a trend book for JCDecaux (the street billboard/furniture/toilet/biking company) on cities, mobility and new media.