Portions of some of these lines have been abandoned .
Portions of some of these lines have been removed over the years due to the loss of their customer base or due to redundancy occurring after mergers that eventually combined all three of the original lines into one system .
Portions of some of these lines have been abandoned and removed over the years due to the loss of their customer base or due to redundancy occurring after mergers that eventually combined all three of the original lines into one system .