By Sarah Wrenn
At 2:49 AM on March 24, 2014, a Blue Line Commuter train entered the Chicago-O’Hare International Airport Station, collided with the track bumper post, and proceeded to derail landing on an escalator and stairway. Thirty-two passengers and the train operator were injured and transported to nearby hospitals. Images showing the lead rail car perched on the escalator look like the train was involved in filming an action movie.
So what caused a Chicago Transit Authority (CTA) train, part of the nation’s second largest public transportation system, to derail? We can use the Cause Mapping process to analyze this specific incident with the following three steps: 1) Define the problem, 2) Conduct the analysis and 3) Identify the best solutions.
We start by defining the problem. In the problem outline, you’ll notice we’ve asked four questions: What is the problem? When did it happen? Where did it happen? And how did it impact the goals?
Next we’ll analyze the incident. We start with the impacted goals and begin asking “why” questions while documenting the answers to visually lay out all the causes that contributed to the incident. The cause and effect relationships lay out from left to right. As can be seen in the problem outline, this incident resulted in multiple goals being impacted.
In this incident, 33 people were injured when the train they were riding derailed in the O’Hare station thereby affecting our safety goal of zero injuries. The injuries were caused by the train derailing, so let’s dig in to why the train derailed. Let’s first ask why the train operator was unable to stop the train. Operator statements are crucial to understanding exactly what happened. Here, it is important to avoid blame by asking questions about the process followed by the operator. Interestingly, 45 seconds before the crash, the operator manually reduced the train speed. However, at some point, the train operator dozed off. The train operator’s schedule (working nearly 60 hours the previous week), length of shift, and time off are all possible causes of the lack of rest. Evidence that the operator was coming off of an 18 hour break allows us to eliminate insufficient time off between shifts as a cause. In addition, the train operator was relatively new (qualified train operator in January 2014), but also she was an “extra-board” employee meaning she substituted for other train operators who were out sick or on vacation.
Next, let’s ask why the train was unable to stop. An automatic breaking system is installed at this station and the system activated when the train crossed the fixed trip stop. The train was unable to stop, because there was an insufficient stopping distance for the train’s speed. At the location of the trip stop, the train speed limit was 25 mph and the train was traveling 26 mph. While the emergency braking system functioned correctly, the limited distance and the speed of the train did not allow the train to stop.
The train derailing impacted multiple organizational goals, but also the personal goal of the train operator who was fired. During the investigation, we learn that the train operator failed to appear at a disciplinary hearing and had a previous safety violation in which she dozed off and overshot a station. These details reveal themselves on the cause map by asking why questions.
The final step of the investigation is to use the cause map to identify and select the best solutions that will reduce the risk of the incident recurring. On April 4, 2014, the CTA announced proposed changes to the train operator scheduling policy. In addition, the CTA changed the speed limit when entering a station and moved the trip stops to increase the stopping distance. Each of these identified solutions reduce the risk of a future incident by addressing many of the causes identified during the investigation.