How to model role and different activities

I am new in the database design and I'm facing this problem, I hope somebody can help me.

In my domain we have 3 roles, Non-Supervisor, Supervisor, Manager.

I created a Person table and a role table for every role and added a table

Person_Role

Pk- PersonId

Pk- RoleId

Pk- StartDate

EndDate

Every role make daily different Activities and a set of activities are called a Journey.

The problem is that because Journey and Activities depend of the role I created the properties for Journey and Activities based on the role but I don't know if this is correct or should I continue with the idea that all Person has a Journey.

Please take a look at my image, I explained better. Thanks a lot

http://ift.tt/15RuETM