system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: On the road, why do we have speed bumps instead of speed grooves?
gpt
Several reasons:

* It’s easier to add a bump on top of an existing road surface than it is to dig a groove into one.
* Bumps do not retain water, and so do not suffer damage associated with it (e.g. freezing).
* Bumps are more visible at a distance than grooves.