Maryland drivers have received more than 1 million speeding tickets from work zone speed cameras over the past three years, and many of those tickets were issued even though no one was working in those zones at the time.

The controversial cameras raked in $18.9 million in 2011, adding to the $30.7 million they generated in their first two years of operation. The cameras have now issued more than a million tickets, according to data from the Maryland State Highway Administration.