A yellow line divides traffic flow in opposite directions, and motors are not allowed to cross the line, according to New York Safety Council. The same rule applies to double yellow lines, but motorists can cross under certain circumstances, such as when making left turns out of driveways.
When there is a broken line next to a solid yellow line, this means that motorists on the side of the solid line cannot pass, according to the California Department of Motor Vehicles. The broken yellow line means that motorists can cross as long as doing so is safe. Motorists are never permitted to drive left of double yellow lines unless it is a carpool lane that has a left entrance or if drivers are instructed to do so by construction workers. Two pairs of double yellow lines with a space of 2 feet or more form a barrier that cannot be crossed by making U-turns or left turns.