Tuesday’s night Amtrak train derailment in Philadelphia, which appears to have been caused by the train’s excessive speed around a tight curve, has left many wondering who is responsible for what on American trains. A modern-day train typically has two to five crew members responsible for operating it. The two required no matter the type of train are an engineer and a conductor; the former is responsible for operating the locomotive, while the latter plays a supervisory role over the entire operation. The two work in unison.

An engineer sits in what the layman may call the driver’s seat. He is directly responsible for the speed at which a train travels and for relaying operational information to the conductor, who usually take on the responsibility of communicating with higher-level operators to inform and be informed of delays and need-to-know information. Both conductors and engineers are trained specifically for each locomotive and each route they will operate on, because they all require different styles of operation. For example, a train carrying coal through the American Midwest is operated differently from a passenger train traveling between Eastern Seaboard metropolises. The train model that derailed in Philadelphia is the fastest passenger train in the U.S. and requires unique operating training.

Generally, engineers “monitor speed, air pressure, battery use and other instruments to ensure that the locomotive runs smoothly; use a variety of controls, such as throttles and airbrakes, to operate the train; [and] communicate with dispatchers over radios to get information about delays or changes in the schedule,” according to the Department of Labor’s Bureau of Labor Statistics.

Conductors are responsible for the train’s entire crew, whether that be just the engineer or the handful of other crew members some trains need, like locomotive firers and switch operators. The conductor will relay information to the crew members to ensure the efficient operation of the locomotive. In some cases, the conductor personally operates track switches and inspects equipment. On a passenger train, they also oversee interactions with passengers.

The Bureau of Labor Statistics says conductors “Check passengers’ tickets; take payments from passengers who did not buy tickets in advance; announce stations and give other announcements as needed; help passengers to safety when needed; [and] deal with unruly passengers when needed.”