The inquiry commission led by
CP and
REFER collected information about the events that led to the collision. According to their report, shortly before arriving at Alfarelos, the regional train encountered a caution signal (solid yellow), meaning that it would find a red signal at Alfarelos. As the driver slowed down the train, so that it would stop before the red signal, it started slipping on the rails. locomotive was pulling the InterCity train involved in the crash, and suffered heavy damage. The driver was not able to stop the train on time. before the signal, with the train travelling at ,
CONVEL triggered the emergency brakes. This was not enough to stop the train which
passed the signal at danger at a speed of and stopped after the signal. Following the rules for this type of incident, the driver contacted the REFER Lisbon Operational Command Center (CCO Lisboa), awaiting instructions on how to proceed. The train could either be told to go back to the signal, or to continue ahead. At the same time, the InterCity train passed through the same caution signal at , and faced similar problems. After braking for , the train speed was still , which prompted the driver to use the
sander. This train was also unable to stop on time, and passed the signal at danger with a speed of , moment at which CONVEL triggered the emergency brakes. Shortly after, at 21:15, this train collided with the regional train, at , destroying the last car and damaging other two. ==Aftermath==