Solution - Autoglass?

Interesting find - remembered my lecturer talking about this material at Edinburgh Napier. This material replicates normal glass you would find on a phone or window, but effectively "heals" itself when etched or cut.

Take a look at the link below or the youtube clip elaborating on the material.

http://www.pocket-lint.com/news/109456-autoglass-self-healing-phone-glass

Using this material in conjunction with another idea culd solve the issue of etching and graffiti on bus stops. Stay Posted.