Four drive belts were discovered “missing” from the motors on a MARTA escalator that malfunctioned and left 21 people inside the Vine City station with injuries ranging from bumps and bruises to broken bones, according to a report from the state agency that oversees escalator and elevator safety.
State inspectors with the Office of Insurance and Fire Safety talked to MARTA officials, first responders, the escalator maintenance contractor and victims of the mishap. They also examined the internal mechanisms of the escalator before releasing the report on Monday.
The report, obtained by The Atlanta Journal-Constitution through the Georgia Open Records Act, cites a large number of people on the escalator at the time of the incident and the missing belts as likely causes.
“Three drive belts were noted during (the) investigation to be missing from the top drive motor, and one belt was missing from the bottom drive motor,” state safety inspector Jerrold Miller wrote in the report. “It is unknown if the belts were missing at the time of the incident or if the belts came off the pulley due to the incident.
“Due to the high passenger volume and the motor drive belts missing, this would have caused an over-normal operating speed condition leading to the injuries.”
The first page of handwritten notes taken by Miller ends with this entry: “Belts were off drive!”
The incident happened at the Vine City station, just past midnight July 15 as crowds were leaving a Beyoncé concert. The escalator sped up and then stopped suddenly, throwing people into a pile on the platform at the foot of the moving stairs.
Although the report says high passenger volume is a cause, it does not say passengers on the stairs exceeded the operating capacity of 8,000 pounds. It also does not appear to address whether the brake system should have engaged when the escalator began to careen downward, as multiple experts have previously said to the AJC.
The report seems to contradict MARTA’s account that there was “nothing wrong” with the escalator mechanically. Transit agency officials said the issues were caused by a “stampede” on the escalator. But witnesses, victims and security camera video footage all appear to dispute that explanation.
MARTA officials declined to comment on the report, citing potential litigation.
Miller met with MARTA representatives and mechanics from maintenance contractor Schindler on July 16, the day after the incident. When they removed two steps of the escalator to examine it, Miller saw “all three drive belts were missing on the top drive motor pulley,” he said in the report.
“We proceeded to examine bottom drive motor, one belt was off the pulley and the other two belts had walked to the top side of the pulleys,” the report says.
Credit: Georgia Office Of Insurance and Safety Fire Commissioner
Credit: Georgia Office Of Insurance and Safety Fire Commissioner
If the belts did come off while the escalator was functioning, it could have caused the stairs to accelerate rapidly, said Tony Boom, an electrical engineer who’s worked with escalators for over 30 years. Boom was one of three experts who said in a previous AJC story that brake failure was a likely cause of the accident. He is not involved with the state’s investigation.
Boom, who reviewed the state report and supporting documentation at the AJC’s request, said the escalator wouldn’t have been operational if all drive motor belts had been missing before the incident. He said the escalator safety system should have detected the overspeed and stopped it.
Boom said he still believes a brake issue is ultimately to blame.
The brakes should have engaged “within about 100 milliseconds, a tenth of a second” when the escalator began to move too quickly, Boom said. The fact that they did not and the escalator careened downward for just over seven seconds indicates a brake issue, regardless of what caused the initial malfunction, he said.
The state report does not address whether the brake should have engaged. The AJC has reached out to the agency for clarification.
Regardless, Boom said the amount of people seen on the escalator in surveillance footage shows that it was not overloaded, certainly not enough to cause it to accelerate without stopping.
“There was something else wrong,” he said. “Something else caused the over-speed.
“When most of the people were off the escalator, as you look at the top of it, the escalator is still over-speeding. So why is it still going, moving pretty quickly, and most of the people are off? That tells me the brake is not engaged.”
The escalator was installed in 2011 and had just undergone routine maintenance on July 10, days before it failed, according to work logs provided by MARTA.
Annual, semiannual and quarterly maintenance tasks were marked off in addition to the typical items checked monthly. Brake capacity was among the items checked.
The Vine City escalator will remain out of commission while it is repaired, according to the state’s report.
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