A diesel locomotive sitting in a railyard at two in the morning with nobody aboard isn't broken or forgotten — it's running on purpose, and turning it off would cost more than leaving it on. Modern diesel-electric locomotives run on complex systems that take 20 to 45 minutes to reach proper operating temperature, and shutting them down in cold weather risks fuel gelling, coolant freezing, and lubrication failures that can permanently damage engines worth over a million dollars. Anti-idling laws have pushed railroads toward automatic engine start-stop systems and shore power connections — but on mainline freight operations, the calculation remains unchanged. A locomotive that never stops running is cheaper to operate than one that does.
