The St. Mary Parish Sheriff's Office says the state transportation department has barricaded some intersections along Highway 90 to let traffic flow more smoothly through the parish.
Sheriff's office spokeswoman Traci Landry says the traffic is probably people evacuating from parishes east of St. Mary Parish as Tropical Storm Isaac gets closer. The storm is expected to become a hurricane before making landfall Tuesday.
She says that at Thurgurson Road in Berwick and Southeast Boulevard and Wal-Mart in Bayou Vista, traffic cannot cross the highway, and traffic lights are set to green for traffic moving east and west.
As of Monday, there were no evacuation orders or road closures in St. Mary Parish, and patrols have been increased parish-wide.