George Westinghouse contributed to railroad transportation primarily through option 1: His invention of air brakes made railroad travel safer and faster.
Westinghouse's air brake system, developed in the late 19th century, greatly enhanced the safety and efficiency of train operations by allowing for quicker and more reliable stopping of trains. While he was involved in various innovations and developments in other areas, including electrical systems, his work on air brakes is one of his most significant contributions to the railroad industry.
The other options do not accurately reflect Westinghouse's contributions: he did not develop the sleeping car, invent the steam engine, or create a railroad network.