The woman behind the wheel of a Chicago Transit Authority bus when it veered off Lake Shore Drive and crashed into a tree told union officials Monday that the power-steering system on the bus failed.
A review of the video surveillance video and the driver's statement also refute claims that at least one passenger grabbed the steering wheel in an attempt to help regain control.
"Her account is more in line with the people I talked to today that something went wrong with that bus," said ATU Local President Darrell Jefferson.
CTA officials said they'll speak again with the driver soon.
Union officials said the CTA is not maintaining its buses properly but could not say whether that played a role in Saturday's crash.
They're pushing for an independent investigation into the matter.
The CTA denies the poor maintenance claims.