Every winter, railroad switches freeze and moisture breaks down subway motors, wreaking havoc on the vehicles of Massachusetts Bay Transportation Authority.
But transportation officials say Boston’s snowiest seven-day period in history has made running the subway and commuter rail trains even more challenging, severely compounding the problems for an already-stressed transit system and causing delays on every subway and commuter rail line.
“There are a number of things that we do to get ready and prepare our trains for winter service,” said Jeffrey D. Gonneville, the chief mechanical officer of the T. “The difference right now is that we have a lot of snow in a very short period of time.”
Transportation officials have repeatedly said the record-breaking snow accumulation has undermined the quality of service for both the commuter rail and the subway. The problems have been so rampant that T officials have said it may take a week for service to get back to normal.
The setbacks left T officials with fewer working subway trains than normal on Tuesday. Joe Pesaturo, a T spokesman, said about half of the Red, Orange, and Blue line cars were out of service. Almost 20 percent of Green Line cars were offline.
Light, fluffy snow can be a headache for the T because it can lead to failures in the trains’ propulsion systems, according to Gonneville. Those problems were the most prevalent for the Red and Orange line cars Monday and Tuesday, he said.
The T’s subway trains use propulsion equipment mounted at wheel level, Gonneville said. When the trains run in the winter, snow packs around the units and gets sucked into the filtration systems, especially if the snow is light. Once it melts within those units, the water drips into the propulsion equipment, causing the electric motors to break down.
Lots of snow — and in turn, lots of moisture — lead to big problems for transit systems. In the last week and a half, Gonneville said, the T has gone through 60 traction motors for the Red and Orange lines — the amount of motors that typically wear out over an entire winter.
While the T has enough replacement traction motors right now, it is “certainly running low,” Gonneville said.
“We didn’t expect to have to go through so many,” he said.
The winds and continual snowfall also created substantial drifts on the Red Line. Ice on the third rail probably caused the power loss that forced the T to suspend Red Line service from Quincy to Braintree on Monday evening; one car was stranded for about two hours on the tracks.
T officials have struggled to remove snow at a pace to keep up with the storms, Gonneville said. When trains broke down during Monday’s morning and evening commutes, snow-covered rights of way and switches prevented workers from getting the cars back to the carhouse and yards quickly for repairs.
MBTA officials also blame an aging fleet of cars. “We have Red Line trains that were in service for the blizzard of 1978, which were also in service for the blizzard of 2015,” said Pesaturo, the T’s spokesman.
The snow and plummeting temperatures similarly affected the commuter rail, delaying trains almost across the board. On the commuter rail, the problems have a cascading effect: For example, one Greenbush line train broke down at Quincy Center Tuesday morning, delaying five trains behind it.
Like the T, Keolis and union officials cited older equipment. The snow gets into the air intake systems of the trains, or causes power outages when it builds up on electrical systems outside the trains, they said.
Mac Daniel, a spokesman for Keolis, the commuter rail operator, said in an e-mail frozen switches, which help trains go from one track to another, caused most delays. “The snow piles up, freezes overnight, and the switch won’t work and the signals (to the engineer) won’t turn green,” he wrote.
To fix them, Keolis sends workers to use brooms, scrapers, and blowers to clear switches. Some switches have heaters that can be turned on remotely to prevent freezing, he said.
Thomas Murray, president of the local chapter of the Transport Workers Union of America, said frozen brakes and doors on commuter rail equipment also become common hazards in winter weather. He said more indoor facilities would help commuter rail workers repair the machines and shield them from the elements.
“This winter seems to have been worse than any winter we’ve had in the past ten years, as far as being able to handle the snow,” he said.
Pesaturo, the T spokesman, said employees were working hard to make sure commuters could rely on the system.