Be extra careful driving on your Saturday morning errands this weekend.

Because that pedestrian crossing in front of you may actually be an undercover cop.

The Chicago Department of Transportation and the Chicago Police Department kick off the start of the city’s annual Crosswalk Enforcement Initiative at three locations on the Southside this Saturday.

According to the CDOT website, the three locations on Saturday will be:

8 AM      Essex Avenue and 79th Street
10 AM    Commercial Avenue and 88th Street
Noon      9141 S. South Chicago Avenue

Essentially at each location, off-duty police officers posing as pedestrians will step off from the curb and into the crosswalk as a vehicle approaches. If the driver fails to yield to the pedestrian and allow them to cross safely (as required under both municipal and state law), the motorist will be pulled over by police officers laying in wait further down the street.

A crosswalk violation could cost a driver anywhere from $50 to $500.

According to CDOT, signs are posted at each crosswalk enforcement zone to alert drivers and pedestrians alike.

“Providing a safe pedestrian environment is our No. 1 goal,” said CDOT  Commissioner Bobby Ware via press release. “This initiative is designed to increase awareness among motorists about the importance of stopping for pedestrians. People should be able to safely cross the street in their neighborhoods.”

State law has changed since the start of last year’s enforcement program. Now drivers must stop and yield to pedestrians trying to cross a street at any crosswalk–not just at stop signs and traffic lights–even if the crosswalk is not marked.

The Crosswalk Enforcement Initiative is a program started in 2009 to improve pedestrian safety. In 2010, the program’s second year, the program expanded from just day time enforcement to include night time enforcement operations as well.

The Crosswalk Enforcement Initiative program will continue regularly from Saturday until the end of September.

Just drive carefully, and always yield to pedestrians.