Why are manholes typically on the road and why are there sometimes 2 or 3 very close together?

Question

Why are manholes typically on the road and why are there sometimes 2 or 3 very close together?

In: 4

Answer 1

Sometimes manholes were placed outside of the road, but the road was made bigger, so the manholes are now in the road. Like if there was originally a two lane road, then the road was made into a four or five lane.