By Kim Smiley

On July 24, 2013, a train carrying 247 people violently derailed near Santiago de Compostela Spain.  Over 130 were injured and 79 were killed as a result of the accident.  Many details are still unknown, but investigators have determined that the train was traveling about twice the posted speed over a curved section of track.

The derailment was the worst train accident Spain has suffered in 40 years.  Obviously, an investigation is underway and authorities are eager to identify what caused the accident and are working to prevent anything similar from occurring in the future. One of the ways this accident can be analyzed is by building a Cause Map, a visual format for performing a root cause analysis.  A Cause Map visually lays out the different causes that contributed to an accident in an intuitive format that shows the cause-and-effect relationships.

The Cause Mapping process begins by filling in the basic background information for an issue as well as identifying how the incident impacted the goals.  In this example, the safety goal is clearly impacted because there were fatalities and injuries.  The schedule, labor, and material goals were also impacted because of the time and resources needed to investigate and clean up the accident and the damage to the train.  The negative publicity surrounding the accident can also be considered an impact to the customer service goal because people may be hesitant to ride trains if they have concerns about safety.

So why did the train derail?  The train was going too fast to safely navigate a curved section of track.  The train was going fast because it had previously been running on track designed for high speed trains where high speeds were permitted and it didn’t slow down as it entered a section of track where the posted speed was lower.  Operator action was required to slow down the train and it appears that the operator failed to take action.   Investigators are looking to whether there was a mechanical problem of some kind that prevented the train from reducing speed, but early indication is that the operator simply failed to brake and reduce the speed of the train.

A number of factors seem to have contributed to this deadly error by an experienced train operator who was familiar with this portion of track.  European Rail Traffic Management System (ERTMS) automatically controls braking and is installed on most of the track high speed trains operate on in the region, but not on the track where the accident occurred.  The accident occurred at the first potentially dangerous curve after the transition to  track where operator action is necessary to brake the train.  Based on statements by the driver,  he missed the transition to  the track where manual braking is required and didn’t realize that the train was in danger.  It has also come to light that the train driver was on the phone with the train’s ticket inspector immediately prior to the derailment and this distraction likely played a role in the accident.  The initial investigation findings have led to the train’s driver being provisionally charged with multiple counts of homicide by professional recklessness on 28 July 2013.

Regardless of whether the driver is convicted on the charges, the automatic systems involved should be a focus of the investigation.  The safety system sent a warning to the operator about the high speed prior to the accident, but it failed to prevent the accident.  Investigators need to review the timing of the warning and determine whether it came too late.  Other automatic systems such as the ERTMS also have the ability to stop a train that is operating at unsafe speeds, which raises the question of whether the safety systems used on this portion of track are adequate since the accident happened.  Ideally, a single error by a train driver for any reason won’t result in dozens of deaths.

To view a high level Cause Map of this incident, click on “Download PDF” above.  Click here to view a video of the accident.