Probably this. Makes sense to me:
Snow Emergency Declared for Fairfax County
Feb. 10, 2010
Residents urged to stay home and stay off roads.
Snow emergency declaration prohibits parking or impeding traffic on designated routes.
A snow emergency has been declared for Fairfax County. All roads designated with signs as a “snow emergency route” are now being enforced – it is unlawful to park any vehicle on a snow emergency route or to impede traffic in a vehicle that is not equipped with snow tires or chains.
The Fairfax County Police Department will remove any vehicle that is stalled, stuck, parked or abandoned on a snow emergency route. The owner or operator of a vehicle that is moved will be responsible for the towing fee, as well as a fine of $25.
http://www.fairfaxcounty.gov/news/2010/county-snow-emergency-declared.htm