The MBTA is looking into whether certain parts of the new Orange Line trains were “appropriately designed,” after discovering that the mechanical failure found in nine new cars may have been caused by ill-fitting materials.
Erik Stoothoff, chief engineer and acting chief operating officer, said the “end connector,” or the connection point to the frame body, is potentially undersized for the cable that is being used to provide grounding in the new train cars.
“All failure points have been cracking or cracked terminal end connectors,” Stoothoff said. “So, not an integral failure of the cable itself or the connection of the cable to the terminal end. The failures have all been cracked terminals at the bolted connection point.”
He said the issue does not lie with assembly of the vehicles, but rather in how the new cars were designed.
The MBTA received a supply of replacement cables from CRRC, the Chinese company manufacturing and assembling the new Orange and Red Line trains, and is putting those new parts into place, Stoothoff said.
It also initiated an engineering review to determine whether the power cables need to be replaced with ones of a different size, or if the cars potentially need a different-sized terminal or connector, Stoothoff said.
The MBTA is hopeful that there will be a resolution to that engineering review by the end of this month or early February, he said.
Weekly inspections have been performed on the new Orange Line fleet since the MBTA removed nine cars from service in late December.
At the time, the MBTA reported that a power cable failure in an “electrical grounding component” had been discovered during a routine inspection.
Steven Culp, chief of safety engineering and construction, said grounding cable straps were found to be disconnected and hanging underneath the affected trains. Power cables were coming into contact with train axles, which may have caused electrical arcing.
Any axle that shows signs of rubbing from the cable has been removed and replaced with a new axle, Stoothoff said.
If that rubbing condition is allowed to go unmitigated for too long, Stoothoff said, “you could create metallurgical changes to the steel or to the metal of the axle, that could end up resulting in cracking and a long-term safety risk.”
It’s the latest setback for the nearly $1 billion CRRC project, which has been riddled with delays and a number of issues, including a braking problem and battery failure, that led T to pull the new Orange Line trains out of service on several occasions.
An update on the CRRC procurement will be provided at next Thursday’s Board of Directors meeting.