A special enforcement effort to crackdown on impaired driving during Super Bowl weekend gets under way Friday.  The Putnam County Sheriff's Office and Carmel Police will participate in the statewide STOP-DWI Crackdown through February 3rd. Sheriff Robert Langley says research shows that high-visibility enforcement can reduce impaired driving fatalities by as much as 20 percent. Sobriety checkpoints play a key part in raising awareness about the problem.  Langley says anyone hosting a Super Bowl party should ask attendees to designate a responsible driver before the game begins.  The law enforcement agencies have a new mobile app called Have A Plan to help make sure people who drink don't drive and get a ride.