Roadside shrines help to refocus one's attention throughout the day on what really is important and necessary. Of course, their mere presence does not do this. One has to be aware enough to notice them.
Here are a few pictures of some of these shrines:
Pope John Paul II had this mosaic installed above St. Peter's Square.
I cannot remember where this one is.
This shrine is just to the left of the entrance to the Congregation for the Doctrine of the Faith. I especially like the angels guarding the Virgin and Child.
This one isn't really a shrine. It is above the entrance to the Church of the Holy Rosary.