Hacked street sign

Mr Abraham said he had also left his stamp on 10 signs in Glasgow. He said he had picked Scotland because he had a cultural affinity with the country and its green landscape, and he singled out Edinburgh due to its "beautiful" architecture. The artist takes between two days and two years to come up with each design before hand drawing it and then putting it onto a computer to make a sticker.

He has hacked signs all over the world and been arrested in Japan. He was caught by the police several times but has usually been allowed to carry on once he has explained to the police that he is "not a vandal". He said: "I take care to do it at night and it doesn't take long as I've already made the stickers but yes I have been caught in Italy, London and Japan.

It was the worst day of my life. He makes extra signs he then sells to private clients and buys the signs from councils who take them down. He was struck by the incongruity between the beauty of the Renaissance city and the road signs peppering its streets.

He has also worked in several other European cities, as well as in New York, where local authorities have mostly turned a blind eye. Other authorities have taken a dimmer view. Abraham is involved in an ongoing legal dispute with the Tuscan town of Pistoia, and his girlfriend was arrested in Osaka, Japan in January on charges of vandalism and breaking road-traffic laws.

He superimposed a stylised naked woman on a no-entry sign, and dedicated the artwork to his partner, Mami Urakawa, who is still being held in Japan. If it has not been changed, it has been posted on the internet.

The standard password for ADDCO-made road signs has been easily findable since at least , when the automotive news blog Jalopnik published a post with instructions on how to access and reprogram the equipment. Mueller said instruction manuals that come with signs include language explaining the security settings, but he also told StateScoop this is standard procedure for road-sign manufacturers.

In either instance, Mueller said, the factory-default password is the same. A—holes on bikes. Invasions of the undead are a recurring theme in road-sign hacks.