What characterizes a "divided highway"?

A divided highway is characterized by the separation of opposing lanes of traffic through a physical barrier or median. This design enhances safety by reducing the likelihood of head-on collisions, as vehicles traveling in opposite directions are kept apart. The median can be constructed from various materials, such as concrete, grass, or pavement, and serves as a clear demarcation between lanes.

In contrast, the other options do not accurately define a divided highway. A roadway with no traffic lights could include various road types, but it does not inherently imply any separation of lanes. A highway designated only for trucks focuses on vehicle classification rather than the arrangement of lanes. A one-way road with two lanes may not feature any separation between opposing flows, which is essential in defining a divided highway.