Imagine landing a plane without the help of air traffic controllers. These controllers advise pilots on how to navigate takeoffs and landings without colliding with other planes. Granville T. Woods invented the device that allowed train dispatchers to do the same thing in 1887. Woods' invention is called the multiplex telegraph, and it allowed dispatchers and engineers at various stations to communicate with moving trains via telegraph. Conductors could also communicate with their counterparts on other trains. Prior to 1887, train collisions were a huge problem, but Woods' device helped make train travel much safer. Woods also received a patent for a steam boiler furnace for trains, as well as for an apparatus that combined the powers of the telephone and the telegraph.