Complex sentence: The first line had been built and operated by the Buenos Aires and Pacific Railway, a British-owned company which original projects included a railway to connect Argentina and Chile but then the BAPR focused on getting access to Buenos Aires.
Split into simpler sentences: The first line had been built and operated by the Buenos Aires and Pacific Railway, a British-owned company. The original projects included a railway to connect Argentina and Chile, but instead the BAPR focused on getting access to Buenos Aires.