Many of those projects would significantly impact riders in communities of color. The state has not followed through on commitments to add 18 trains to the Orange Line, extend the Silver Line underneath Chinatown to South Station and Logan Airport, increase bus ridership by 12,000 riders, connect the Red and Blue lines directly and file an environmental impact report on the Urban Ring, a plan for a rail line circling Boston and connecting other rail lines.

While pushing back the deadline for these projects, the state and the MBTA have found hundreds of millions of dollars to build commuter rail lines in recent years.

“I think that the strategy of the MBTA is to do the simplest things first,” said state Rep. Byron Rushing. “So even if they have things on the list, they will do things that are relatively simple like fixing stations. You don’t have to have arguments with communities about land. That is why they like the commuter rail — because the stations are far apart.”

Funding has been allocated to renovate stations along the Red Line in Dorchester, the Blue Line in East Boston and the Fairmount Line commuter rail in Dorchester. In addition, the MBTA has retrofitted or replaced hundreds of buses so that they now burn compressed natural gas, reducing the buses’ emission of air pollutants in neighborhoods such as Roxbury where there are high asthma rates.

However, no new train lines have been built or expanded in densely populated urban areas. The Silver Line bus service between Dudley Square and Downtown Crossing, created two years ago, is hardly a replacement for the elevated Orange Line that was torn down along that route over a decade ago, Roxbury activists have long said, despite the MBTA’s promise to build something “equal to or better than” the old Orange Line.

The MBTA plans to renovate the Fairmount Line stations at Upham’s Corner and Morton Street, but the state failed to pass a bill that would have provided the money to build proposed new stops along the line. The new stops would make the Fairmount Line a de facto inner-city rapid transit service. Instead, neighborhood residents are left with buses as their only public transportation option.

Despite the lack of rapid rail lines in much of Roxbury and Dorchester, two of the most public-transit dependent neighborhoods in the system, the MBTA has pushed ahead with plans for the Greenbush Line Commuter Rail south of Boston.

The expensive Greenbush Line, like the Big Dig, has caused controversy.

“I have no problems doing commuter line extensions,” said Somerville-based Congressman Michael Capuano, who is among those urging the state to begin work on its backlog of public transit projects. “But they are spending $500 million on the Greenbush project with no federal funding, and the project they chose to prioritize will service 5,000 people a day. Shouldn’t you use the money to serve more people?”

The extension of the Silver Line underneath Chinatown also may not benefit very many riders.

Currently, most Silver Line riders come from the predominantly black neighborhood of Roxbury. Some riders interviewed questioned the benefit to black riders of an extension to South Station.

“Why do they want to change it?” asked Chris, a retail clerk. “We’d prefer it to stay the way it is. You don’t see black folks getting off the Red Line at Broadway Station.”

Jesse, a recruitment specialist who works downtown, said the extension would not benefit him.

“Why do I need to go to South Station?” he asked. “It’s just more work, tearing up our streets and driving up our taxes.”

The Silver Line extension would funnel buses underground to Boylston Street Station on the Green Line, then under Essex Street to South Station. This would make it harder for riders to get to Downtown Crossing. Boylston Street Station is four blocks further away from Downtown Crossing than Temple Place, which is currently the end of the line.