What does a solid yellow line indicate on Italian roads?

A solid yellow line on Italian roads indicates that no overtaking is permitted. This marking serves to enhance safety by informing drivers that it is unsafe or illegal to pass another vehicle in that particular area. Such lines are typically found on two-way roads where visibility is limited or where road conditions may pose increased risks for drivers attempting to overtake. This regulation helps in maintaining smooth traffic flow and reduces the likelihood of accidents.

In contrast, the other options describe situations that do not align with the purpose of a solid yellow line. Overtaking encouraged or indicating a bike lane are not functions of solid yellow lines; instead, those situations are typically represented by different road markings. Similarly, pedestrian crossings are usually marked with distinct symbols or lines, rather than solid yellow lines, to ensure they are easily identifiable to drivers.