Don’t try to plead ignorance: After handing out warnings for weeks, Sandy Springs police announced Tuesday night they will start writing tickets against those driving unlawfully on the Ga. 400 shoulder. Right now.

Sandy Springs police said in an email that they would immediately begin “aggressive enforcement” of flex lane rules in their stretch of southbound Ga. 400 -- two days earlier than it was previously reported they would start issuing citations.

The Georgia Department of Transportation on May 14 opened to morning rush-hour drivers the southbound right shoulder of Ga. 400 from Holcomb Bridge Road to the North Springs MARTA station exit in the Roswell and Sandy Springs areas.

Shoulder-riding is allowed only from 6:30 to 9:30 a.m., Monday through Friday. Unauthorized motorists caught in the lanes at other times face tickets, fines and possible jail time.

“The need for aggressive enforcement stems from drivers abusing the lane usage during non-flex-lane hours,” police said. Such actions, they said, “affects timely emergency vehicle response to accident or other emergencies on GA 400 which requires the use of the emergency lane.”

For example, on June 1, emergency vehicles were hampered responding to an accident involving  an overturned vehicle outside the flex lane test area because drivers were using the emergency lane for travel.

“We must remain vigilant with our concerns regarding response times until we know that they are not unreasonably affected by emergency lane use by citizens,” Sandy Springs police Chief Terry Sult said in the email.

Roswell police have said they would stop anyone riding the shoulder unlawfully in their part of Ga. 400 and leave it to the officer’s discretion whether to issue a warning or a citation.

According to a GDOT website, motorists cannot ride the Ga. 400 shoulder outside the morning rush, but transit buses can. Trucks with more than six wheels cannot use the lane at any time. The speed limit is 45 mph. Unauthorized shoulder riding can lead to a ticket and a fine of up to $1,000 or up to 12 months in jail.