Sounds like somebody at the T saw 'Stripes' one time too many

The EM-50 Urban Assault Vehicle
features a variety of weapons
and armor plating as well as an
extensive set of communications
and navigation equipment. It looks
ideal for use on the Green Line,
doesn't it? Guide to the EM-50.

You gotta love the story in today's Globe: MBTA unit with big, bad bus has seen little action.

On city streets, it has the subtlety of a tank, and that is before it engages its strobe lights.

The large, jet-black bus has four surveillance cameras on its roof trained in every direction, and looks like the kind of tool an authoritarian regime might use to scare or scoop up dissidents and other malcontents.

The Outraged Liberal, however, is a bit less than enthralled, noting the story points out how many times the T has actually rolled out the commando team who would use the bus (which would be, um, er, almost never).

... The Toy Cop Unit was forced as a response to the realization they had no effective means to deal with the civil disobedience that never developed at the Democratic National Convention. The fact there has never been a need for them and they have set off an arms race with competing police agencies is irrelevant. ...

Why not a fully equipped rail car with a special posse on horseback? Pull into the station, blow the whistle and let them loose? It worked in Butch Cassidy and the Sundance Kid. But then again the horses didn't need to get up the stairs or through the turnstiles.