THE CHAIRMAN of the MBTA’s Fiscal and Management Control Board raised the possibility on Monday of expanding the authority’s fleet of buses and using private contractors to both operate and maintain the vehicles.

The T has contracts in place with the unions representing bus operators and machinists that allow the transit agency to privatize operations beyond specified core levels. Aiello, the chairman of the control board, said the agency should explore the feasibility of hiring private contractors to operate and maintain buses beyond the core level of 955 buses.

Currently, the T has 1,024 buses in its fleet. Its current procurement strategy calls for replacing the older vehicles in the fleet by purchasing 40-foot hybrid electric-diesel buses (194 on order), 60-foot buses with as-yet undetermined propulsion systems (up to 460 needed), 40-foot battery electric buses (up to 35 needed), and at least 32 new 60-foot Silver Line buses capable of running with no emissions in the tunnel coming out of South Station.

Many of the T’s existing repair facilities are crumbling and bursting at the seams. T officials said one garage has room for about 70 buses but routinely tries to squeeze in more than 90. Aiello said it may be possible for a private operator to provide service from its own or a new facility while the T repairs and possibly expands its existing garages.

The debate about the size and makeup of the bus fleet is coming at a time when the T is also trying to improve the quality of its bus service. The T plans to release a state of the bus system report either later this month or in January. The agency is also revising routes and changing stops to make service more efficient and to improve on-time performance. The authority is also working with municipalities on dedicated bus lanes and other measures to speed up service.

By most measures, the T’s bus operations are performing poorly. According to statistics released Monday, the T is failing to meet its service delivery standards on most routes. In Boston, which has 99 routes, 92 percent of them are failing the service reliability standard, 41 percent are failing comfort standards, and 78 percent are failing frequency standards.

The stats are similar for Cambridge and Somerville. In Malden and Chelsea, 100 percent of the routes are failing the T’s reliability standard.

“The bus service does not work for our riders,” said Monica Tibbits-Nutt, a member of the control board.

She urged T officials to move much faster with their efforts to improve service. Current plans call for implementation of improvement measures next fall, but Tibbits-Nutt said the timetable needs to be moved up to the summer.

Brian Shortsleeve, another control board member who previously served as general manager, said T staff shouldn’t just be trying to improve all of the existing bus routes. He said the T should also do away with under-performing routes entirely.

“There’s a lot of these routes we shouldn’t be running and probably shouldn’t have run for a couple decades,” he said.