Which line indicates that overtaking is prohibited in both directions?

The presence of a solid yellow double center line is a widely recognized traffic control mark that indicates overtaking is prohibited in both directions. This marking serves as a warning to drivers that it is not safe to cross the line for the purpose of passing another vehicle. The solid lines emphasize the danger of oncoming traffic and are utilized in areas where visibility may be limited or where the road conditions do not allow for safe overtaking maneuvers.

In contrast, a broken yellow line typically indicates that overtaking is permitted in one or both directions, depending on the road's layout and signage. A solid yellow line alone may indicate that overtaking is not allowed in one direction but does not apply to the opposite direction, which can still permit overtaking movements. A center line, depending on its format, may not convey the same restrictions regarding overtaking and may represent a different set of driving regulations.

Therefore, the strong visual cue given by the solid yellow double center line is crucial for ensuring safety on the road, as it communicates clear and enforceable restrictions on overtaking movements for drivers in both directions.