Brian Clague is a busy musician who makes up to eight trips a day on the MBTA and tells GlobeWatch he’s aggravated by what he calls the T’s “infuriating’’ practice of sending several Green Line trains at once for no apparent reason. Though it happens on the B and D lines, too, the problem most often occurs on the C line, he says.

“C trains outbound [come] in rapid succession, the first being jammed full and the rest being almost empty, and then expressing three of them in a row past freezing passengers waiting for an inbound train,’’ he wrote in an e-mail. “Perhaps rush hour is the worst. Obviously some allegedly professional dispatcher is sending these trains when what we need is simply a train every x minutes, x being a smaller number at rush hour or during sporting events or other large crowd moments. . . . What’s particularly infuriating is when you’ve waited for a long time, can’t get on the first train, squeeze onto the second train, and then they announce that they are expressing that train to thus and so and everybody has to get off and wait for a third train, onto which they may or not get on.’’

Clague says the problem also exists on bus lines, particularly the No. 1 bus that travels between Cambridge and Roxbury.

“The T can explain it as a traffic issue but it’s not, it’s a dispatch issue, which you can determine by sitting in Harvard Square and watching the departure frequency of the No. 1 bus. They’ll send four No. 1 buses — one right after another — and then not send another for half an hour. I think some of this is the drivers wishing to get to the end of their run for their coffee break, or to sign out and go home,’’ he wrote.

European cities use computerized dispatch systems to make sure service matches the appropriate level of demand coverage, Clague says.

“Is it really rocket science to send a train out at regularly scheduled intervals — perhaps adjusted for rush hour or known traffic jams like ballgames — to avoid this wasteful use of empty trains? I think the arrival of a new MBTA general manager provides an excellent opportunity to see if the GM intends to look into this as both a resource management and customer service issue.’’

THE MBTA RESPONDS “The Green Line schedules trips on the Beacon Street line every six minutes from Cleveland Circle during the rush hours,’’ wrote Lydia Rivera, a Massachusetts Bay Transportation Authority spokeswoman, in an e-mail. “The Green Line schedules trips on the Beacon Street line every six minutes from Cleveland Circle during the rush hours,’’ wrote Lydia Rivera, a Massachusetts Bay Transportation Authority spokeswoman, in an e-mail.

“Once a train leaves, many variables like intersections, autos on the right of way, and heavy passenger boarding . . . can take place,’’ she wrote. “Green Line operators never make adjustments such as expressing or holding on their own.’’

The spacing between cars is monitored by inspectors and dispatchers who have a better picture of what’s going on by monitoring vehicles remotely on computer screens to gauge train traffic, she said.

“They make adjustments like expressing of trains or crossing back trains at Coolidge Corner and/or short-tripping in an attempt to get trains back on schedule. If we didn’t do that, we would be running behind schedule inbound and outbound. We do not have the luxury to ‘go around’ a train,’’ she wrote.

Rivera added “every attempt’’ is made to get trains back on schedule and to reduce delays by having staffers “constantly’’ review schedules to make necessary adjustments. As for drivers who skip over waiting passengers, Rivera said that’s not allowed and the T “will interview and possibly discipline employees who are in violation of our rules.’’

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