What happens to glass on the roadway over time?

Over time, glass on the roadway undergoes changes due to environmental factors, such as weather conditions and mechanical abrasion from traffic. As glass is exposed to these elements, it tends to wear down at the edges, gradually becoming rounded. This process is often associated with the action of vehicles rolling over the glass, which can smooth and round off sharp edges, making the glass less hazardous compared to its original state. This transformation is particularly relevant in the context of road safety, as sharp-edged glass can pose a significant danger to both motorists and pedestrians, while rounded glass is less likely to cause injury.

The other options represent characteristics that do not align with the natural degradation process of glass on roads. For example, glass does not remain sharp-edged as it ages on the roadway; instead, it wears down. While glass might experience colorations or inclusions based on its type and any potential coatings, the primary physical change in the context of road safety is the rounding of edges, which mitigates the risk posed by broken glass on the streets.