Railroad derailments can occur due to a wide variety of causes, such as collisions between trains, improper maintenance, sleep-deprived or overworked train crews, or mechanical failures involving a train's railcars or engine. Traveling at inappropriately high speeds during poor weather conditions can also cause a train to derail.
Another reason a railroad derailment may occur is that the responsible parties fail to remove obstructions at a railroad crossing. Furthermore, derailments can be the result of a train colliding with trucks or other vehicles at crossings. In some other cases, the derailment is attributed to inadequate training of the crew operating the train, while other times a switch misalignment can be to blame.
Railroad derailments can pose health and safety hazards to many people. Passengers and crew members aboard the train may suffer injuries or death, as can bystanders, depending on the location of the derailment. Another concern is that trains sometimes transport chemicals that are toxic to humans. In the event of a derailment, such chemicals can spill out of the train and into the environment, placing people in the area in danger. In severe cases, it may be necessary to evacuate an entire small town until the chemicals are no longer in the air.