Keolis Commuter Services canceled four times as many trains this fall than last year, one of the worst stretches since the record-breaking winter of 2015 and a stark illustration of the transit system’s persistent struggles to keep enough trains in service.
From September through November, the commuter rail operator canceled 222 trains, compared with 51 over the same span the year before, a Globe review has found.
The 81 trains canceled in October marked the highest monthly total since February 2015, when it snowed more than 60 inches in Boston. (Keolis dramatically reduced service in March, leading to fewer official cancellations.)
Last month was even worse, with 98 cancellations, although 55 were related to a planned shutdown for bridge construction in Needham.
Cancellations hit a 10-month low in May, with only six across the entire system, but began increasing afterward.
The Fairmount Line, which runs through diverse and low-income sections of Boston, has long been particularly hard hit by cancellations. Since Keolis began operating the commuter rail for the Massachusetts Bay Transportation Authority in 2014, more than twice as many Fairmount trains have been canceled than any other line’s.
The number of unexpected cancellations from mechanical issues has improved recently, particularly on the Fairmount Line, and even the increased number of cancellations this fall represented less than 1 percent of all rides.
But reliability issues, which extended across the system and frequently involved rush-hour trains, point to larger problems with Keolis’s mechanical department and its equipment, some of which had to be shipped to other companies because workers could not conduct mandated inspections quickly enough.
Riders and transit advocates said the increase in cancellations was troubling, especially with winter coming.
“If you have so few trains that you can’t go through inspections without canceling random trains, you obviously haven’t set up a sufficient system to work the current schedule that you have,” said Rafael Mares, vice president of the Conservation Law Foundation, a Boston environmental group that pushes for better public transportation.
Officials at Keolis said the agency has experienced a shortage of available coaches because of a backlog in federally required inspections that must be completed every four years.
The problem became so acute this fall that Keolis shipped 19 coaches to Delaware and another location in Massachusetts to make headway.
Those safety inspections have been required for years. But David Scorey, Keolis’s new general manager, said the mechanical department fell behind two winters ago, when brutal weather conditions forced constant repairs to aging equipment.
The effects are still being felt, he said. At one point in early October, Keolis had 338 available coaches, well short of the 359 required to run the entire line, Scorey said.
Scorey said he doesn’t consider the delayed inspections a failure on the company’s part.
“It’s a fact that this backlog built up,” he said. “It’s partly as a result of so many cars being damaged from the winter of 2015, and it meant the capability was stretched to its limit at that time.”
Scorey said the company has taken steps to solve the problem. Since the summer, Keolis has added more than 80 workers to the mechanical department, which will help shrink the inspection backlog. When the coaches are returned from the outside companies, they should be caught up, he said.
But advocates said the backlog underlines a broader problem: the system lacks the basic infrastructure and equipment to deliver on its new schedule, which runs more trains and is less forgiving when problems arise. Blaming the inspections, Mares said, “misses the fact that there aren’t enough vehicles to make up for problems.”
“It may not just be a logistical issue,” he said. “It may be a resource issue.”
For the most part, Keolis has publicly acknowledged its struggles with late trains, particularly on the busy Framingham/Worcester Line, whose trains were tardy about one-third of the time last month.
The overall number of on-time trains is higher, though still lagging last year’s: In November, about 85 percent of all commuter rail trains ran on time, compared to about 87 percent last year.
The MBTA posts those on-time statistics on its website, but statistics on canceled trains aren’t clearly on display , as they are counted as late trains.
As the Globe reported in October, riders of the Fairmount Line have experienced more than their share of cancellations. Latest data show that between July 2014 and November 2016, there were 530 cancellations. The next highest total, just over 200, was on the Lowell Line, which runs more trains.
The cancellations were caused in part by the diversion of trains to busier suburban lines, company officials acknowledged. After the revelations, Representative Michael Capuano called on the Department of Justice and the Federal Transit Administration to review whether Keolis Commuter Services violated civil rights laws by redirecting the trains.
Since the outcry, Keolis officials said they have changed the policy to prevent certain trains from taking the brunt of cancellations. Company figures show that just one Fairmount train was canceled in November, compared with 18 in October.
Other lines weren’t so lucky. The Framingham/Worcester Line, which runs to South Station, had just two cancellations in October, but 14 in November.
Riders have noticed. Vincent Sestito, a Stoughton line commuter who has taken the commuter rail for 30 years, said it has been a “horror show” recently. Trains have been more crowded — and he has seen several rush-hour trains canceled.
“I haven’t seen all this improvement that Charlie Baker has been talking about,” he said as he walked to his train, which on this day was on time. “It’s been talked about, but what are they doing?”Nicole Dungca can be reached at email@example.com.Follow her on Twitter @ndungca.