Fredericksburg police Officer Tom Worthy balanced on the front rack of his ATV, nailing a big white "Posted" sign to a tree.

He'd nailed a similar sign there just three weeks ago. But the ATV riders who, weekend after weekend, break the law by riding on trails through city-owned property along the Rappahannock River, had torn it down.

This time, Worthy used about six nails--all ribbed so as to be difficult to pull out.

"They're really going to have to work for that one now," he said, hopping off his four-wheeler, hammer in hand, at the site in southern Stafford County.

City officials have put up dozens such signs over the years, warning people that even though there are trails on the property, and even though some riders have been riding there for years, it's illegal and always has been.

But the problem, and the complaints, are getting worse.

Off-roading is gaining in popularity, while the area is gaining in population. That means more riders, more residents and more complaints.

So, Worthy and fellow police Officer Steve Buchanan, as well as Assistant Director of Public Works David King, went out to the city's property this weekend, putting up about two dozen warning signs along the river. The signs warn that motorized vehicles are not allowed. And had the officers come across any riders, they would have cited them.

Posting signs won't keep people out, but the city hopes they'll prompt at least a few ATV riders to turn around and find a legal place to ride. And the signs--as well as the police presence of Worthy and Buchanan--may placate area residents who complain that ATV riders cross their property and disturb the peace with their loud machines.

Members of the Rappahannock Ridge Estates homeowners association have complained plenty--mostly to the Stafford Sheriff's Office, which has sent deputies out to the housing development off Richards Ferry Road.

Resident Dave Riley--who walked down the road to investigate as Worthy, Buchanan and King were unloading their ATVs from a Fredericksburg police trailer--said many offenders are county residents. But deputies have also told him they've caught riders from Prince William County and other locales.