COLUMBUS, Ohio (WCMH) — Visitors to John Glenn Columbus International Airport are being warned not to engage in a dangerous parking trend that drivers might not realize is illegal.

On its Facebook account, the airport posted a photo of several vehicles parked along the eastbound side of International Gateway, which leads into the airport. A giant red circle with an X drawn through it is placed over the parked cars.

“PLEASE DO NOT DO THIS,” the caption reads. “Parking on the side of the road on International Gateway is prohibited and very unsafe.”

According to the airport, two free parking options exist for people waiting to pick someone up. The first is the Cell Phone Lot, located just before the rental car center behind the John Glenn International sign on International Gateway. The second is the Green Lot, which has a one-hour grace period that allows free parking for 60 minutes or less.

“We get it, being closer to the terminal makes it feel like a convenience,” the post’s caption continued. “But, sitting on the side of a busy roadway is not safe. Please use the resources available to SAFELY pick up and drop off passengers.”

The airport recently announced expanded parking options with the enlargement of the Red and Green Shuttle Lots. Customers are encouraged to make a parking plan using the online tools, which provide real-time availability for each lot on its website before arriving.

The airport does not allow curbside parking, and unattended vehicles will be ticketed and/or towed.