Road engineers run diesel-electric engines (or locomotives powered by battery or electricity) that transport passengers or freight. Before a run, they first look at their trip orders. They may discuss with the conductor instructions, timetables, and precautions for moving dangerous cargo. They check the locomotive, ensuring adequate amounts of fuel, sand, and water.
Engineers sit in the cab of a locomotive. During a run, they operate the throttle to start and accelerate the train, and the airbrakes to slow and stop it. They monitor gauges, dials, and meters that measure speed, fuel, temperature, battery charge, and air pressure in the brake line. They also watch for and obey signals, both along the track and those received by train radio, which indicate obstructions on the track, other train movements, and speed limits.
Locomotive engineers must be familiar with their routes, knowing where curves and bridges are and what the safest speeds are for traveling over them. They must be able to adjust speed gradually, without disturbing passengers or damaging cargo. They must also be aware of the content and nature of their trains, because the number and kind of cars and whether they are empty or full affects the way the train reacts to speeding up, slowing down, and going on hills and curves.
Yard engineers work in the switchyards and run locomotives or switch engines that are used to move freight or passenger cars when trains are being broken up or put together for a run. Yard engineers called hostlers drive locomotives to and from maintenance shops. Some engineers spend several years on yard work, and later take up freight or passenger service work. Most, however, spend their careers in one type of work or the other.