Boston Globe by Adam Vaccaro

As it lumbers onto Third Street near the Tobin Bridge in Chelsea, the 111 bus is often beyond standing room.

More than 60 riders are squeezed into its 40-foot interior, pressed against the doors and each other, contorting for some small space and tolerable position as the bus lurches along its route. At each stop, the bus idles as boarding passengers fumble through purses, pockets, and wallets for change.

Eventually, the 111 grinds its way through grueling traffic going up to and across the Tobin Bridge to deposit its riders for another day of work in downtown Boston.

“We wait a long time, and when we get into the bus, we can’t fit,” said Roberto Rodriguez, a longtime 111 rider from Chelsea. “There’s eight people on top of you. It’s scary.”

The 111 is a rolling case study of all the problems that confront the Massachusetts Bay Transportation Authority as it seeks to improve bus service: overcrowding, delays caused by traffic and passengers who pay in cash, and frequent cancellations.

It is also an endurance test for passengers, who for $1.70 and anywhere from 20 minutes to an hour of discomfort and indignities get a lifeline from working-class neighborhoods in Chelsea to the economic engine in downtown Boston.

“That bus is essential for a lot of Chelsea residents,” said City Manager Thomas Ambrosino. “This is a city with a lot of economically disadvantaged residents. They depend on the cheapest form of public transportation to get themselves to and from work.”

Photo by Lane Turner/Globe Staff

Photo by Lane Turner/Globe Staff

MBTA bus riders have reason to feel neglected: On-time performance lags significantly behind the subways and commuter rail, and the vagaries of street traffic can make any trip downright frustrating. But the bus system is a major facet of Greater Boston’s transportation network, with more than 350,000 daily riders across 175 routes. And it serves a higher percentage of low-income riders than the T’s other modes of transportation.

“It makes it more challenging. We try to put on as many as we can,” said Mike Martelli, a longtime 111 operator. “You could pick up 20 people on the bus stop, and two minutes later there’s 10 more people.”

Officials finally pledged to fix the problem after a sharp rise in cancellations across the system last year, blamed on an uptick in driver absences. The T is planning to hire 55 additional bus drivers, five of whom will be dedicated to the 111.

It will also require dispatchers to seek approval from supervisors for each canceled 111 trip, and is considering banning cancellation of back-to-back buses on the route. Fewer cancellations should relieve congestion inside the buses: The T says the 111’s passengers were overcrowded 21 percent of the time last fall — the worst rate in the system and far above the agency’s own standards.

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