Westbrook police plan to come down hard on drunk drivers this summer and fall.

On Saturday, police conducted a safety checkpoint on Westbrook Arterial, stopping more than 150 cars traveling both east and west. Four people were charged with operating under the influence.

Other drivers were issued summonses for illegal transportation of alcohol by a minor, operating with an expired license and operating the wrong way on a divided highway.

According to Capt. Tom Roth, Saturday’s arrests marked the beginning of a major enforcement effort to crack down on drunk drivers. It is being funded through a grant by the Maine Bureau of Highway safety.