LEXINGTON COUNTY, SC (WIS) - The train tracks are now clear following Sunday's deadly Amtrak-CSX collision.
Wednesday marks day four of the investigation in Lexington County.
NTSB says that this will be a long process. The investigation could reportedly take 12-18 months.
Officials will also continue examining the scene by looking inside and outside of the rail cars. This process is expected to take several days.
They will also still be looking at the event data recorders, which reveal the final seconds before the collision.
So far, the Amtrak train's event recorder reveals that the train's horn was activated as it traveled 56 miles per hour down the track. Five seconds before the crash, the train's brakes were applied. Three seconds before the crash, the train's emergency brakes were applied.
One of the main issues the NTSB is looking into is why a switch was padlocked, which caused the Amtrak to veer off course.
WIS will continue to update this story throughout the investigation.