Final answer:
You cannot cross double solid lines on two-lane roadways to pass other vehicles, but left turns through them may be allowed. Safety distances for crossing depend on speed, road conditions, and visibility, with around 6 car-lengths being a typical safety benchmark in city conditions.
Step-by-step explanation:
On two-lane roadways with double solid lines, certain rules apply to ensure traffic safety. You cannot cross double solid lines to pass another vehicle. This is a universal traffic rule meant to prevent collisions and maintain the orderly flow of traffic. Double solid lines typically indicate that visibility is limited or it's otherwise unsafe to pass.
However, turning left through double solid lines to enter or exit a roadway, such as at a driveway or intersection, is usually permitted unless otherwise specifically prohibited by traffic signs. Always ensure it is safe to turn, and yield to any oncoming traffic before crossing.
As for the safety distance for crossing a road with traffic, there is no one-size-fits-all answer. A safe distance depends on factors such as the speed of the approaching vehicle, road conditions, and visibility. A commonly used benchmark is that each car-length is approximately 15 feet, so it is advisable to ensure there is enough space for a car to stop or for a person to get out of the way—often around 6 car-lengths or more in a typical city scenario but could be more at higher speeds or less favorable conditions.