What does the term "PM rush hours" commonly refer to?

The term "PM rush hours" typically refers to the busy hours in the early evening when commuting traffic tends to peak. This period usually occurs when many individuals are finishing their workday and traveling home, leading to increased congestion on roadways and greater demand for parking spaces. During these hours, parking enforcement may be heightened to manage the influx of vehicles, as the availability of parking can be significantly impacted by the volume of commuters.

In contrast, the other options address different aspects of traffic patterns or parking regulations. Morning high traffic periods denote a different time frame that is usually referred to as "AM rush hours" and doesn't align with the concept of PM rush. Periods of low traffic simply do not correspond with the term "rush hours," as the latter implies a concentration of vehicles. The mention of days when parking is free also does not relate to traffic patterns and is more concerned with parking policy rather than traffic flow dynamics.