Complex sentence: The THI&E was never prosperous enough in the 1920s to replace its aging fleet of wood interurban cars but many were rebuilt and modernized, and much of the town streetcar line system was reequipped with one-man Birney streetcars.
Split into simpler sentences: The THI&E was never prosperous enough to replace its aging fleet of wood interurban cars, but many were rebuilt and modernized. Much of the town streetcar line system was reequipped with one-man Birney streetcars.