The preliminary investigation of Tuesday morning's  train derailment indicates the cause was an improperly secured piece of replacement rail that was stored on the tracks; the cause appears to be human error, not a track defect. 

Storing equipment in between tracks is a common practice employed by railroads across the country to accelerate rail repairs. The key to this being an effective and safe practice is making sure that the extra equipment is properly bolted down, which does not appear to have happened in this case. 

NYCT is inspecting every inch of rail to ensure that each and every replacement part is properly stored and secured. Nothing is more important than the safety of our customers. The investigation into this incident continues.