The National Highway Traffic Safety Administration is testing faux speed bumps that are painted on the road. Their substance is merely an optical illusion, but apparently they slow people down. Until they realize the bumps are two dimensional anyway. From the Associated Press:
The 3-D markings are appealing because, at $60 to $80 each, they cost a fraction of real speed bumps (which can run $1,000 to $1,500) and require little maintenance, said Richard Simon, deputy regional administrator for the highway safety administration.
On one of three streets tested in the Phoenix trial, the percentage of drivers who obeyed the 25 mph speed limit nearly doubled. But the effect wore off after a few months.
"Initially they were great," said the Phoenix Police traffic coordinator, Officer Terry Sills. "Until people found out what they were."
Fake speed bumps (Associated Press)