By Kim Smiley
Four passengers were killed and dozens more sent to the hospital after a metro train derailed in the Bronx early Sunday, December 1, 2013. At the time of the accident, the train was carrying about 150 passengers and was traveling to Grand Central Terminal in New York City. The aftermath of the accident was horrific with all seven cars of the commuter train derailing. Metro-North has been operating for more than 30 years and this was the first accident that resulted in passenger deaths.
A Cause Map, or visual root cause analysis, can be built to help analyze this accident. There is still a lot of investigative work that needs to be done to understand what caused the derailment, but the information that is available can be used to create an initial Cause Map. The Cause Map can easily be expanded later to incorporate more information as it becomes available. The first step when building a Cause Map is to fill in an Outline with the basic background information. The impacts to the goals are also documented on the bottom of the Outline. The impacted goals are then used to begin building the Cause Map.
In this example, the safety goal is clearly impacted because there were four fatalities and over 60 people injured. The schedule goal is also significantly impacted because this portion of rail will be closed during most of the investigation. The National Transportation Safety Board has estimated that the investigation will take 7 to 10 days. The track closure is particularly impacting because this is a major artery into New York City with a ridership of 15.9 million in 2012. Once the impacted goals are documented, the Cause Map itself is built by asking “why” questions.
So why did the train derail? The details aren’t known yet, but there is still some information that should be documented on the Cause Map. A question mark is included after a cause that may have contributed to an issue, but requires more evidence or investigation. It’s useful to document these open questions during an investigation to ensure that all the pertinent questions are asked and nothing is overlooked. (If it is determined that a cause didn’t play a role, it can be crossed out on the Cause Map to show that the cause was considered, but ruled out.) Two factors that likely played a role in the derailment are the speed of the train and the track design where the accident occurred. There is a sharp curve in the track where the derailment happened. Trains are required to reduce their speed before traveling it. The latest reports from the investigation are that the train was traveling 82 mph in a 30 mph zone. The train operator has stated that the brakes malfunctioned and didn’t respond when he tried to reduce speed and that the train was traveling too fast over the curved track.
Investigators have recovered the data recorder from the train which will provide more information and if there was a problem with the brakes. Investigators will also interview all the relevant personnel and determine what happened to cause this deadly crash. Once the investigation is completed, any necessary solutions can be implemented to reduce the risk that a similar accident occurs in the future.
To view a completed Outline and initial Cause Map of this incident, click on “Download PDF” above.