Road network manager class

Hello, I want to have a dynamic road network in my game. Therefor I create a RoadManager actor, which is responsible for adding, deleting roads, add crossings and so on, also it’s reponsible for calculating the ways which vehicles drive. I think it’s better for that to have a great manager class, which holds all the informations.

This class should be available only once, so I created a property in my gamemode class and set this to the static class of the manager.
Is the gamemode the right option for creating and saving this instance, or should this be in another place?