The Horner Road lot, near Interstate 95 and the Prince William County Parkway, has 2,363 parking spaces that are usually filled by 6:50 a.m., forcing latecomers to park on the grass or along throughways that aren't legal parking spaces.
State police left fliers last week notifying drivers they will start ticketing illegally parked cars Monday. It's a matter of public safety, officials said.
"Some of these cars are parking where they're not supposed to be parking, and you've got other cars trying to go around them. We're concerned about people walking in that lot," Virginia State Police spokeswoman Deborah Cox said, adding that police had received many complaints about the lot.
Prince William County Supervisor Frank Principi agreed.
"If someone's parking somewhere that's going to preclude police or fire or EMS to get where they need to go, then a ticket does need to be issued. It's a public safety issue," he said.
The lot has been choked with cars ever since the nearby Potomac Mills Mall closed off hundreds of parking spaces once available to commuters.
Matthew Hess, a Woodbridge commuter who regularly picks up "slugs" -- fellow car poolers -- so he can ride the high-occupancy vehicle lanes to work in D.C., said he tries to avoid the Horner lot.
"I can see where it can be difficult to park," he said. "I'm afraid to even go there to catch a ride because it just looks too chaotic. It just seems disorganized."
Secretary of Transportation Sean Connaughton announced earlier this year that the state would build a new $7.2 million, 600-space lot only a quarter mile from the Horner lot, but that is expected to take another year.
In the meantime, the county has leased 370 spaces from a Woodbridge church, and commuters are encouraged to try parking in Dale City or further south, at the lot near Route 234 and Route 1.