Greater Boston's most popular form of larceny appears to be cheating the MBTA out of fares. All told T management estimates that it could be losing up to $42 million annually. 

The T estimates the Green Line loses up to $4.5 million per year when passengers board above-ground trains through rear doors at rush hour. Fare evasion on buses costs up to $2.4 million annually.

As a result, you could soon see teams of fare-checkers at the rear doors of Green Line trolleys. They'll require proof of payment for all the Green Line stations beyond Kenmore Square where riders can get on board the trolleys at the surface level and use the back doors to skip out on paying.

MBTA Chief Administrator Brian Shortsleeve sees two problems:

"The first is our own inability to collect fares on the surface Green Line and the failure of Keolis conductors to collect all the fares, all the time," he said. "We also have a problem with fare evasion, with riders who knowingly and intentionally do not pay their full fare. We need to deal with both of these problems."

The T estimates over 9 percent of Green Line riders use the rear doors at surface-level stops. Anywhere between $1.3 million and $4.5 million in lost revenue flies right out those Green Line rear doors when riders don't pay up. The severity of fare evasion on the Commuter Rail is harder to pin down, but operator Keolis estimates it could be around 10 to 15 percent of ridership, or up to about $25 million.

Keolis is also bringing on more conductors to improve fare collection on busy trains and is suggesting new metal gates at North, South and Back Bay Stations to make it easier to check payment.

The T's management board wants to put a long term solution–a new on-board fare system–in place in two years.

In related news, the powerful panel of reformers hand-picked by Gov. Charlie Baker also heard that the membership of the MBTA Retirement Fund is now majority retirees and not active employees.

The T's pension board has long been about as nontransparent as an organization dealing with public money can get. To pay for the legions of retired MBTA workers, the $1.6 billion fund receives millions from the transit agency, but the fund rarely lets anyone–including MBTA officials–look into its books.

"But I think there's a general move toward transparency," Michael Mulhern, the fund's executive director, told reporters after his presentation to the board, pointing out recent audits and reports available to the new regime at the T.

The fund is only 65 percent funded, Mulhern told the board, leaving about $500 million in unfunded liability.

"That's getting lower and lower, and that means there's a huge liability coming down the road for not only that, but for retired T employees as well," said Mary Z. Connaughton, director of governmeny transparency at the Pioneer Institute, a fiscally conservative think tank.

But like most everything involving the MBTA's finances, a few million here and a few million there is a good indicator of how the T is being managed, but those figures pale in comparison to the billions the agency would really need to fund its current state of good repair and other projects.