The honeymoon is over for motorists who have been driving in the I-70 Mountain Express Lanes when they’re not supposed to.

The Colorado Department of Transportation gave drivers a 30-day grace period when it came to driving illegally in the mountain express lanes, but that came to an end Friday.

Beginning July 21, drivers who break the law will be issued $75 fines that increase to $150 if not paid within 20 days. Violations can include driving in the express lanes when they’re closed, weaving across the solid yellow line and driving an oversized vehicle in the express lanes.

During the grace period, a staggering 5,640 warning were mailed to drivers who violated the rules. That’s an average of 188 per day.

“The number of warnings issued during the grace period is extremely concerning,” Tim Hoover, a CDOT spokesman, said in a news release. “We don’t want to see so many people get fines — we just want roadway users to follow the Express Lane rules so everybody can get to their destinations safely.”

CDOT said the I-70 Mountain Express Lanes are actually “peak period shoulder lanes” and are narrower than typical highway lanes, which is why oversized vehicles, like RVs, semi-trucks and vehicles pulling trailers, are not permitted.

Federal regulation also bar CDOT from keeping the lanes open year-round. The I-70 Mountain Express Lanes can only be used a certain number of days per year and are emergency shoulders the rest of the time.

That’s why, CDOT said, it’s so dangerous to drive on them when they’re closed because of the risk of colliding with a disabled vehicle or an emergency responder.

“These civil penalties really boil down to safety,” Hoover said. “Motorists in violation of these simple rules may think they’re saving travel time by driving dangerously or ‘outsmarting the system,’ but in reality, they’re creating life-threatening risks for themselves and everyone else on the road. We hope this program is the reminder people need to drive safely and follow the rules.”