Baltimore’s Red Line has its share of critics, from those who oppose the idea altogether to those who prefer a pricier (and faster) subway over light rail, but it seems unlikely much of anyone, pro Red Line or con, wanted future eastbound and westbound light rail trains sharing a single track. That’s the kind of cost-savings measure that used to bedevil the city’s existing light rail service.

Last week, the Maryland Transit Administration announced the single track section planned since last summer for the mile-long Cooks Lane tunnel will no longer be necessary. New ridership estimates have allowed planners to increase the Red Line budget by $121 million. That is more than enough to pay the $67 million cost of building two tracks under Cooks Lane.

It will also buy the MTA a few other improvements, including upgraded signals, a better maintenance facility, some track improvements in the downtown tunnel and four additional vehicles. The changes are modest but helpful, along the lines of building a house with a better grade of lumber — riders may never notice a few minutes less travel time or safety features, but they’ll benefit nonetheless.

With those enhancements, the price tag for the Red Line rises to just under $1.8 billion. Any higher and the project is unlikely to qualify for federal funding under cost-effectiveness guidelines. Some Baltimoreans may prefer a Red Line subway or even a light rail with more tunneling, but the cost would be truly prohibitive — hundreds of millions of dollars more.

Where did the new ridership estimates come from? Officials say it was merely a matter of refining complex computer models that look at such things as land use, demographic forecasts and travel patterns. With the intense competition among states and regional transit organizations for limited federal transit constructions funds, the results are likely to be scrutinized closely.

Yet as helpful as these changes should be, the project faces a far greater challenge much closer to home. The MTA currently lacks the money to pay the state’s 50 percent share of the cost. Construction can’t begin in 2016 as planned unless the state finds new sources of revenue.

In years past, that’s usually meant raising the gas tax or motor vehicle fees. However, Congress is already considering some form of tax on carbon fuels to help pay for pending climate change legislation. With unemployment rates still relatively high, raising taxes on the middle class is not a politically popular notion anyway.

How can the 14.5-mile project linking Woodlawn with Johns Hopkins Bayview Medical Center be financed? That’s a question that needs to be answered before this fall’s elections. Maryland’s next governor will have much to say about whether the Red Line — and two similar projects in the Washington area — ever get built. Transportation policy hasn’t been an issue yet in the opening skirmishes of the governor’s race, but it needs to be.

The region’s economy needs an effective transportation system to create much-needed jobs, particularly for those who live in economically distressed areas like Baltimore’s Edmondson Village or Harlem Park. The Red Line is expected to not only produce 15,000 jobs during construction but also to enhance the region’s other modes of public transit (including bus, subway and commuter rail) that connect people to potential employers.