Va. Code § 46.2-1034
Whenever a vehicle is being driven on a highway or a portion thereof which is sufficiently lighted to reveal any person or object upon such highway at a distance of 350 feet ahead, the operator of such vehicle shall use the low beam of his vehicle's headlights or shall dim the headlights if the vehicle has single-beam lights. Whenever a vehicle approaches an oncoming vehicle within 500 feet, the driver of such vehicle shall use the low beam of his vehicle's headlights so aimed that glaring rays are not projected into the eyes of the oncoming driver or dim the headlights, if the vehicle has single-beam lights. Whenever the driver of any motor vehicle approaches from the rear or follows within 200 feet of another vehicle proceeding in the same direction, the driver shall use the low beam of his vehicle's headlights or shall dim the headlights if the vehicle has single-beam lights.
Va. Code § 46.2-1034