Root Cause Analysis of Passenger Side Door System

This paper presents a real-world application of Root Cause Analysis methods that were applied to analyze and resolve a side door problem that was occurring on a particular fleet of coach cars operated by Amtrak. The foundation of a Root Cause Analysis program is a disciplined engineering process designed to identify physical, human and latent roots of chronic or sporadic problems. This paper presents the engineering challenges encountered while conducting root cause analysis of a complex coach car side doors problem. The coach car side doors system exhibited undesirable characteristics when in service. Mechanical staff received multiple reports that during station stops all of the open side doors would unexpectedly close even though the train speed was at zero. During this unexpected side door closing sequence all of the obstacle detection systems were disabled presenting a potential hazard to the traveling public. The side doors Root Cause Analysis team found the Physical Root cause of failure to be located in the door system software code — a finding that was never suspected following years of trouble with the side doors. As a result of this finding, the door manufacturer corrected the software and issued revised software to be installed fleet-wide. The Human and Latent Root causes were addressed through the development of a standard operating procedure and training for conductors and crew on the proper operation of side doors. The Root Cause Analysis method proved to be a powerful and productive process for achieving a solution to a chronic passenger side door problem.