Updated 03/26/14 - 4:15 p.m.
CHICAGO (CBS) -- Federal investigators said the woman who was operating the Blue Line that crashed at O'Hare International Airport on Monday admitted she dozed off before the crash, and didn't wake up until it derailed and slammed into an escalator.
The CTA saus that in a previous incident in Febrauary, the operator missed a CTA stop after she "closed her eyes for a moment" One car missed the station and the train had to continue to the next station because it did not properly stop. She received a a written warning for the safety violation.
She also told investigators she fell asleep at the controls before the crash on Monday. The crash occurred around 2:50 a.m. Monday.
"She did admit that she dozed off prior to entering the station. She did not awake again until the train hit close to the end of the bumper," Turpin said.
However, the CTA says according to their records she did not "doze off" and only "closed her eyes for a moment"
CTA Operator Admitted Dozing Off Before Blue Line Crash
The operator told investigators she was not taking any medication that would have made her drowsy. Turpin said the results of drug and alcohol tests were not yet available Wednesday morning.
Earlier Wednesday, new video posted on YouTube appeared to show the moment the train jumped the tracks and slammed into the escalator.
The video, which appears to be from a surveillance camera at O'Hare, shows a CTA worker and a passenger talking at the top of the escalator as the train is pulling into the station. As the train derails and the head car crashes into the escalator, ending up just shy of the turnstiles, both men run out of view of the camera.
A few different versions of the video have been posted on YouTube, and some were taken down a short time after they were posted.
The CTA declined to comment on the video, saying only they did not release it.
Turpin did not comment on the video, but said the NTSB has acquired other video of the crash recorded by cameras inside the train, and on the platform. He also said the NTSB has acquired video of the same train at other stations on the Blue Line to help assess the train's condition before the crash.
Investigators have determined the train was traveling approximately 25 mph as it approached the station, which is the proper speed before stopping.
Turpin estimated the crash caused $6 million in damage to CTA equipment -- the cost of replacing the damaged cars. That does not include any structural damage to the station or tracks.
Turpin said automatic braking systems on the train did activate as the train was pulling into the station, and the brakes were trying to stop the train, but NTSB investigators do not yet know why the train did not stop before plowing through bumping posts at the station and barreling up the escalator.
"The train was trying to stop. That's all I can tell you," he said.
Investigators will conduct interviews Wednesday with inspectors who regularly examine mechanical equipment on the train, as well as with emergency response officials and Fire Commissioner Jose Santiago.
Mayor Rahm Emanuel visited the crash scene on Tuesday.
"It's jarring, I suppose is the one word I would use to describe it," he said. "In your mind's eye, you can't imagine the train up on an escalator, and so it's a very jarring picture."
The mayor said the most important thing is no one was seriously injured.
"Had that happened three hours later – in the middle of a rush, not at 3 a.m. – it could have been a whole different situation," he said.
The mayor declined to comment on the operator's admission she dozed off, saying he wants to see a full report from the NTSB on every factor that led to the crash before making any judgments.
More than 30 people were injured in the crash, including the operator. She was hired by the CTA in April 2013, Turpin said, and began training to operate trains later in the year. She received her qualification in January, and had been operating trains for approximately 60 days before the crash.
Turpin said automatic braking systems did activate as the train pulled into the station, and the brakes were trying to stop the train, but investigators don't know yet why the train was unable to stop before plowing through a bumping post and derailing, then slamming into an escalator.
Turpin said investigators have completed their on-scene investigation, and have given the CTA permission to remove the train from the station. He said he did not know how long that process would take, but crews must cut apart the lead car of the train, which is still sitting atop the escalator.
CTA officials have said they will try to tow the other seven cars of the train back onto the track and pull them out of the station.
Once the train is removed, Turpin said investigators will be able to test all of the signals at the station, and inspect the affected track. Investigators already have checked tested signals that are not blocked by wreckage from the crash, and examined track leading up to the crash site.
The damaged train was still sitting atop the escalator Wednesday morning as the National Transportation Safety Board continued its investigation. A six-man team has been sifting through the wreckage for evidence, and has been removing cameras and event recorders from the train to figure out exactly what went wrong.
Turpin has said an automatic stopping system on the train activated as it was pulling into the station at 25 mph around 2:50 a.m. Monday, applying the train's brakes, but that didn't stop it from smashing through a bumper post, and barreling up the escalator.
More than 30 people, including the train operator, were injured in the crash.
At least three passengers who were on the train have filed lawsuits accusing the CTA of negligence, and seeking damages for their hospital bills. All three women were on their way to their respective jobs at the airport, and suffered various injuries when the train crashed.
"We filed a lawsuit to ensure that all evidence is protected and preserved so that a full and complete investigation can be done as to why this happened at O'Hare," said attorney Matthew Jenkins.
While the O'Hare station remains closed, the CTA has been running bus shuttles between the Rosemont stop and O'Hare so passengers can get to and from the airport. The CTA says it hopes to restore normal service by this weekend.
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