Answer:
Granville Woods improve the telegraph by allowing a telegraph station to send and receive voice and telegraph messages over a single wire.
He also invented the Multiplex Telegraph which allowed the train stations to sent messages to moving trains.
Step-by-step explanation:
He was an American inventor, the first African American to be a mechanical and electrical engineer after the Civil War. His Multiplex Telegraph assured a safer and better public transportation between the cities of the United States.
I hope this answer helps you.