Please answer a question about the following article about Portugal:

With the Conference of Berlin of 1884, Portuguese Africa territories had their borders formally established on request of Portugal in order to protect the centuries-long Portuguese interests in the continent from rivalries enticed by the Scramble for Africa. Portuguese Africa's cities and towns like Nova Lisboa, Sá da Bandeira, Silva Porto, Malanje, Tete, Vila Junqueiro, Vila Pery and Vila Cabral were founded or redeveloped inland during this period and beyond. New coastal towns like Beira, Moçâmedes, Lobito, João Belo, Nacala and Porto Amélia were also founded. Even before the turn of the 20th century, railway tracks as the Benguela railway in Angola, and the Beira railway in Mozambique, started to be built to link coastal areas and selected inland regions.

When were railroad tracks being installed Portugese Africa?
before the turn of the 20th century